A Hybrid View of Personal Identity

by

Sommer Hodson

Submitted in Partial Fulfillment of the

Requirements for the Degree

Doctor of Philosophy

Supervised by Professor Alyssa Ney

Department of Philosophy

Arts, Sciences and Engineering

School of Arts and Sciences

University of Rochester

Rochester, New York

2013

ii

Biographical Sketch

Sommer Hodson was born in Boston, Massachusetts and grew up in Rochester, New

York. She attended Oberlin College, and graduated with a Bachelor of Arts degree in

philosophy. She began doctoral studies in philosophy at the University of Rochester in

2007. She received the Master of Arts degree from the University of Rochester in 2011.

She pursued her research in philosophy under the direction of Alyssa Ney.

iii

Abstract

Personal identity is unlike many other metaphysical issues in that it is something

that ordinary people understand and have rational beliefs about, but most leading

accounts of personal identity ignore our pre-philosophical beliefs, as evidenced by the

highly counterintuitive results they yield. I argue that the conflict between these accounts

and our pre-philosophical beliefs should not be taken as evidence that our ordinary

beliefs are incorrect, but that the accounts which contradict our existing beliefs fail to

capture the thing we are actually concerned with when it comes to our own existence

through time. After defending this central role for our beliefs, I survey several

representative accounts of personal identity, arguing that each clashes irreconcilably with

reasonable and deeply-held beliefs about our own existence through time.

My positive claim is that a successful account incorporates elements from both of

the two major types of personal identity account, psychological continuity and physical

continuity. I argue that a hybrid view, according to which a person continues to exist so

long as she has the same psychology in virtue of having the same physical brain, is the

best fit for our actual pre-philosophical understanding of our own existence through time.

The hybrid view yields the expected results in typical situations and provides more

plausible results in hypothetical scenarios than its competitors, while withstanding

objections as well as its competitors.

Finally, I discuss consequences that acceptance of the hybrid view may have for

related questions. I argue that the hybrid view does not require acceptance of any

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particular theory concerning related metaphysical questions, and can thus be accepted

without committing to a position on other matters. I also discuss the ethical implications

of the hybrid view, with particular emphasis on how the hybrid view relates to moral

responsibility.

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Contributors and Funding Sources

This work was supervised by a dissertation committee consisting of Professors Alyssa

Ney (advisor), Earl Conee of the Department of Philosophy, and Professor Richard Ryan

of the Department of Psychology. All work for the dissertation was completed

independently by the student.

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Table of Contents

Introduction 1

Chapter 1 Our Continuity 4

Chapter 2 Considering the Contenders 50

Chapter 3 A Hybrid View 99

Chapter 4 Objections 139

Chapter 5 Further Implications 172

Works Cited 219

1

Introduction

Personal identity is unlike many other metaphysical issues in that it is something

that ordinary people understand and have rational beliefs about, but many of the leading

accounts of personal identity discount our pre-philosophical understanding of our own

continued existence through time, as evidenced by the highly counterintuitive results they

yield. I argue that where leading accounts of personal identity differ from our ordinary

beliefs about our own existence through time, this should not be taken as evidence that

our ordinary beliefs are incorrect, but that the accounts which contradict our existing

beliefs fail to capture the thing we are actually concerned with when it comes to our own

existence through time.

In the first chapter, I defend the central role I’ve given to our intuitions in

selecting an account of personal identity. In the second chapter, I survey several

representative accounts of personal identity, arguing that each clashes irreconcilably with

reasonable and deeply-held beliefs about our own existence through time. Proponents of

these views claim that these counterintuitive results are worth the cost for the theoretical

advantages which their views provide. My interpretation is that these discrepancies

indicate that these accounts do not capture the existence-through-time relation which

concerns us, given that they deviate significantly from what we seem to know about our

own existence through time. Sacrificing intuitive fit for theoretical advantage is a

reasonable philosophical move, but given how widely these accounts differ from our pre-

philosophical beliefs, I claim that these accounts simply are not tracking the relation

about which we have pre-philosophical beliefs.

2

My positive claim, detailed in the third chapter, is that a successful account of our

continuity through time will incorporate elements from both of the two major types of

personal identity account, psychological-continuity views and physical-continuity views.

I argue that a hybrid view, according to which a person continues to exist so long as she

has the same psychology in virtue of having the same physical brain, is the best fit for our

actual pre-philosophical understanding of our own existence through time. The hybrid

view yields the expected results in typical situations, and also provides more plausible

results in hypothetical scenarios than its competitors.

I discuss objections to the hybrid view in the fourth chapter. Because it

incorporates elements of each, some of the objections raised against both physical-

continuity views and psychological-continuity views can be raised against the hybrid

view, given that it incorporates elements of each view. After responding to these

objections, I conclude that they do not seriously undermine the hybrid view.

In the final chapter, I sketch out some of the consequences that acceptance of my

account would have for related questions. I argue that the hybrid view does not require

acceptance of any particular theory concerning related metaphysical questions, and can

thus be accepted without committing to a position on other matters. I also consider the

ethical implications of the hybrid view on attributions of moral responsibility and the

relationship of personal identity to borderline cases of personhood. Because competing

accounts deviate sharply from our beliefs about our own continued existence, they

provide an unsteady foundation from which to answer moral questions stemming from

personal continuity. The hybrid view, for fitting with our pre-existing beliefs about

3

ourselves, serves to confirm the related ethical knowledge we already possess, and

provides plausible guidance in resolving questions that our pre-philosophical beliefs are

not prepared to address.

4

Chapter 1: Our Continuity

1 What is this account intended to do?

There are several similar but distinct matters that fall under the domain of inquiry

of what is often termed ‘personal identity.’ For example, one might wonder what we are

– humans? Persons? Immaterial entities of some kind? One might wonder what sorts of

changes our minds or bodies can endure without causing us to cease to exist. We don’t

cease to exist when we fall asleep, but do seem to cease to exist upon death. What

happens to us in various conditions in between the two, such as conditions where the

body remains alive but the brain permanently ceases higher function? There are also

questions which are not obviously matters of personal identity, but whose answers seem

likely to hinge upon matters of personal identity. When is it appropriate to hold someone

in the present responsible for some past action? Presumably, they must be the person

who actually took the action in the past. What makes this the case? Answering that is a

question of personal identity. The answer to the question of what we are seems likely to

bear on the question of what the boundaries of our morally relevant lives are – when do

gain or lose the rights typically associated with living, functioning adults?

My focus here is on a slightly modified version of a question Marya Schechtman

names the reidentification question: what does it take for person x at time t to be the same

person as person y at time t1? An answer to the reidentification question must not only

provide a way of determining whether x and y are the same person, but also “tell us what

5

it is for him to be the same person.”1 The question I address here is similar, but must be

distinguished in two important regards. First, I focus on continuity conditions, rather

than our identity conditions, in order to avoid assuming that numerical identity is a

necessary condition for our continued existence. I do not wish to rule out by stipulation

the possibility that a person can continue to exist at a time at which there is not a person

numerically identical to her. Thus, I prioritize personal continuity over personal identity.

Because personal identity is the name most often given to this broad area of inquiry, I

refer to personal identity at times throughout. This is merely a concession to the

prevailing usage of the term even among philosophers who deny that identity is what

matters; it should not be regarded as a commitment to numerical identity as a necessary

component of our continuity. The second way my question deviates from Schectman’s

reidentification question is that my focus is on a narrower version: what does it take for

person x at time t to stand in a relationship of personal continuity with (“be the same

person as”) person y at time t1, according to our actual beliefs and practices?

Further elaboration is required about the nature of the matter I am inquiring into.

To whom am I referring when I speak of ‘our’ continuity conditions? What is meant by

‘continuity’? What role do actual beliefs and practices have in an inquiry of this sort?

Once these matters are addressed, there is the further question of whether this is an

inquiry worth pursuing. Is the question of what our continuity conditions are according

to our actual beliefs and practices a question whose answer is interesting, relevant, or

1 Schechtman (1996), 8.

6

informative? What is the basis of my proposed answer to the question, and why should

one consider it? This chapter addresses these issues.

1.1 Our Continuity

As I intend to use the term here, ‘continuity’ refers to continued existence through

time. It is not meant to assume anything in particular about what continued existence

entails. For example, I mean the term to be compatible with perdurantism, endurantism

and other alternatives. Use of the term ‘continuity’ does not entail that continued

existence calls for a single, three-dimensional object existing at various times, nor does it

entail that continued existence is a matter of a series of three-dimensional objects, each

existing at only one time, which together compose a four-dimensional object which exists

through time. Although the word itself suggests otherwise, it is also not my intention to

assume that survival is necessarily impossible when there are gaps in the ‘thread’ of an

object’s existence – that is, if an object x (whether it is a three-dimensional object or a

timeslice of a four-dimensional object or something else) exists at t1, ceases to exist at

intermediate time t2, and reappears at t3, x at t1 may be continuous with x at t3, in spite of

the fact that there is an intermediate time at which was not present. The term ‘continuity’

is not intended to presuppose that x does not survive to t3 because x was not present at t2.

(I will argue for a particular conclusion regarding this later, but the term ‘continuity’

itself is not meant to presuppose this.)

What makes for continuity is the meat of this project, and as such I cannot say

much about it in this preliminary stage. Different accounts of personal identity make

7

different claims about the continuity of persons (or, more accurately, they can be

understood to do so, given that many of the most notable accounts of personal identity are

not meant to directly address the question I am addressing here), and each account’s

particular explanation of what makes for continuity of persons will be discussed when

those accounts are discussed. In the meantime, I hope that the term ‘continuity’ is

intuitive enough to stand in place of a more apt term. It is the relation which ties our past

selves to our present selves, the thing which makes it the case that I who type this

sentence now also typed the beginning of this sentence, the thing which makes it the case

that the child who was me survives today.

I have thus far referred to ‘our’ continuity conditions, ‘our’ survival, without

specifying what I mean by that. But to whom does that ‘our’ refer? Whose continuity

conditions am I talking about? The answer is straightforward: the continuity conditions I

am interested in are the continuity conditions of actual ordinary human people. Because

my focus is on actual people, rather than people simpliciter, I avoid commitment to the

claim that the account of our continuity conditions which I defend is necessarily true. My

claim is more modest, and deals simply with our continuity conditions in the actual world

as they actually are. (‘Actual’ and ‘actually’ are used in the technical modal sense here.)

The question of what our continuity conditions are is intimately connected to the

question of what we are, and there is a risk of circularity unless these two questions are

carefully distinguished. Our continuity conditions can be informative in determining

what we are, just as what we are can be informative about our continuity conditions. It

8

may seem that the question of what we are is more fundamental, but I will begin with a

claim about our continuity conditions, for reasons explained in section 3.3.

1.2 Actual Beliefs and Practices

Perhaps the most contentious part of the question is this final part – according to

actual beliefs and practices. Whether actual beliefs and practices have any role in

answering a philosophical question is a matter I’ll discuss shortly. Here, I mean simply

to clarify what I have in mind by the phrase.

Although it is obvious that specific individuals may have directly contradictory

beliefs about personal identity or the continuity of persons (philosophers who work in

personal identity and take opposing views to one another do, for instance), I believe that

as a whole, our practices and beliefs regarding the continuity of persons can be broadly

understood in a coherent way. By ‘our’ I do not mean philosophers – as noted, there is

definitely not a consensus among philosophers about what the truth is in the matter of

personal identity – but ordinary people. Unlike many metaphysical topics, the continuity

of persons is something that ordinary people are perfectly familiar with: we believe that

we ourselves, as well as those around us, existed in the past and also exist in the present,

and will exist in the future until our deaths. We believe that for every adult, there was in

the past a child they were, and that any child who does not die first will at some point

cease to be a child and instead be an adult. Beyond infancy, we don’t think that people

cease to exist when they go out of sight, and then some other similar human comes into

existence later. We understand that people exist throughout time, and that connections

9

hold between people at different times so there is a fact of the matter about which past

person is me, about which future person will be me. We may not think about the nature

of these connections, but we do understand that it is not random happenstance which ties

us to our past and future selves. Our understanding of that indicates that we accept some

criterion for the continuity of persons.

We do not need to be philosophers to grasp the idea that continuity of persons

exists. Most non-philosophers have probably never thought about what makes for

continuity of persons, but in simply realizing that people exist through time in an orderly

way, they implicitly accept that there are continuity conditions for persons, and they can

tell in simple, ordinary cases whether those conditions have been met or not. Thus,

ordinary people have beliefs and practices regarding the continuity of persons, and it is

these beliefs and practices I have in mind in addressing this question. These beliefs are

not ones which average people are likely to be conscious of, and they are unlikely to

make deliberate reference to them in ordinary situations, but they are revealed through

practices, and individuals do acknowledge such beliefs when presented with scenarios in

which they become apparent. My goal here is to articulate a metaphysically coherent

account of our continuity conditions which incorporates, as fully as possible, the beliefs

revealed by our practices and by our response to hypothetical situations.

The fact that I give a central role to actual beliefs and practices in my question

also places a further limitation on the answer: because I am basing my answer on actual

beliefs and practices, the continuity conditions of things about which we have no beliefs

and practices will not be accounted for. For instance, our continuity conditions based on

10

our actual beliefs and practices may not encompass nonhuman beings which possess the

criteria of philosophical personhood (self-awareness, consciousness, capacity for rational

thought, and so forth), because we are not aware of any nonhuman persons, and as such

do not have any beliefs and practices concerning nonhuman persons.

2 The Role of Actual Beliefs and Practices

My prioritization of actual beliefs and practices in determining which account of

continuity is correct calls for defense. Leading accounts in personal identity generally do

not prioritize fit with actual beliefs and practices. Eric Olson states that our conception of

ourselves is potentially wildly mistaken, and thus is not relevant to the metaphysical facts

about ourselves; he remarks that inquiry into our understanding of ourselves is an

anthropological matter, not a metaphysical one.2 Derek Parfit dedicates an entire chapter

to “what we believe ourselves to be” and another to explaining why our beliefs about our

personal identity are not correct.3 There is also the general assumption that philosophy’s

work is to reveal truths not made apparent by everyday beliefs. If ordinary beliefs

revealed the deeper truths about the world, there would be little value in philosophy; as

Bertrand Russell puts it, “philosophy is merely the attempt to answer such ultimate

questions… after realising all the vagueness and confusion that underlie our ordinary

ideas.”4 Thus, there are at least two questions to be answered before I proceed: is my

2 Olson (2007), 14.

3 Parfit (1986).

4 Russell (2004), p. 1.

11

project actually metaphysical in nature, and can my prioritization of actual beliefs and

practices as a foundation for a belief about personal continuity be justified?

2.1 Metaphysics or Not?

Parfit’s claims that we are not what we believe will be addressed later on, but

Olson’s claim that focusing on what we mean when we speak of ourselves reduces the

question to an anthropological one rather than a philosophical one bears consideration

here. Is this project genuine philosophy, or an anthropological project as Olson would

see it?

I think that Olson’s assessment of a project like this one as anthropological rather

than philosophical is mistaken. The status of our continuity is unlike many other

philosophical issues in that actual beliefs and practices do play a role. Certainly, there

are issues falling under the umbrella of personal identity on which our beliefs and

practices have no impact: the continuity of human animals, for instance (which,

uncoincidentally, is Olson’s focus), seems likely to be a matter of the same rules of

continuity that apply to any other life form. So when we ask, “what are the continuity

conditions of this particular species of animal?” it seems obviously true that what we

believe to be the continuity conditions of that particular animal is not relevant, any more

than the medieval belief that the sun orbits the earth bore on whether it actually did. We

don’t need to have a positive account of what makes for the continuity conditions of a

given life form before we can reasonably assume that our beliefs do not have a role in

dictating those continuity conditions. However, the fact that our beliefs and practices do

12

not bear on the continuity condition of the human animal is only relevant to our

continuity conditions if we understand ourselves as human animals when we consider our

continuity conditions.

Of course, it would be absurd to deny that we are human animals in some sense.

Ordinary, everyday truths (to set aside the associated epistemic issues) like “I have

hands” are true because my body – a Homo sapiens body – has hands. Denying that we

are human animals in at least some sense is not a plausible option. However, we are

unlike other animals in an important regard: we are not only human animals. We are also

persons, in the philosophical sense of the word: we possess certain mental capabilities,

such as self-awareness, consciousness, and the capacity for rational thought which

qualify us as persons.

How is this relevant to the role that beliefs and practices play in giving an account

of our continuity? As noted in the prior section, there are several distinct questions that

can be asked about personal identity and/or personal continuity. Even if we narrow it to

one, for instance “What does it take for person x at time t to be the same person as person

y at time t1?” the answer depends on what the words in the sentence mean. There is

nothing unusual about this; of course the answer to a question depends on the meanings

of the words in the question. Where this question differs from some others is that the

term ‘person’ is equivocal. Context does not make it immediately apparent which sense

of the word is being used in the question, and the question has a different answer

depending upon which sense of ‘person’ is used. If ‘person’ is understood as a synonym

for ‘human being,’ then the answer to that question has to do with the identity and/or

13

continuity conditions of human beings, which, as a particular type of animal, have

continuity conditions determined by the same sorts of criteria as any other species. But

‘human being’ is not the only sense of ‘person’ available. ‘Person’ can be understood in

the philosophical sense – a sense in which personhood is determined not by species

membership, but by possession of certain sorts of mental capabilities such as

consciousness and capacity for rational thought. If, when we ask “What does it take for

person x at time t to be the same person as person y at time t1?” we mean ‘person’ in the

philosophical sense, then it cannot be assumed that the answer to the question has to do

with the continuity conditions of animals, because personhood in this sense does not have

to do with being an animal, but with possession of particular mental features. Olson is

correct that the question of whether we think of ourselves as persons or human animals is

an anthropological question, not a metaphysical one. But the development of an account

of the things that we believe we are, whatever those beliefs may be, is still a metaphysical

matter. The continuity conditions of a given type of object is not the kind of thing that

our beliefs and practices bear on, while the question of which, of a set of closely-related

objects we are referring to is definitely a question about human practices. The former is

addressed through reasoning, while empirical methods resolve the second. So although

there is an anthropological question intimately tied to the metaphysical question of what

our continuity conditions are, this does not render the metaphysical question

anthropological. Whether it is possible to give a coherent account of our continuity that

is compatible with the anthropological facts about what we are is a metaphysical

question.

14

A distinct but related concern about the legitimacy of this project as metaphysics

has to do with the subjective nature of beliefs and practices. Beliefs and practices are

subjective: they change over time, and differ from one culture to another at the same

time. But metaphysics is meant to reveal objective truths about the world. Since beliefs

and practices are subjective, can an inquiry into our continuity conditions based on

beliefs and practices be a legitimate metaphysical matter?

Clarifying the exact role I grant to beliefs and practices resolves this matter. I

agree that it would be a mistake to claim that such-and-such an account of our continuity

conditions is true just in virtue of fitting with our actual beliefs and practices. Our

subjective beliefs cannot change objective truths such as those about the continuity

conditions of a given type of object. However, our beliefs and practices, subjective

though they are, can prove valuable, indirectly, in inquiry into an objective matter: they

allow us to narrow down which objective truth we are aiming at, which question we are

really intending to ask.

Ironically, an analogy made by Olson helps to illuminate my point. Olson asks

the reader to imagine a philosopher who proposes a Locomotive Criterion of identity

because she is so intrigued by our capacity to move around under our own power. The

Locomotive Criterion says that a locomotor (including human animals, other life forms

that move of their own power, and even machines) persists if and only if it can still

locomote. If the capacity for locomotion is lost, the locomotor has ceased to exist.5 The

case is meant to show the absurdity of claiming that the identity of objects has to do with

5 Olson (1997), 32.

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the continued existence of any particular capability of those objects, casting doubt on the

idea that we can identify ourselves as persons, given that doing so is essentially

identifying ourselves with the capability for thought and perhaps other mental abilities.

However, it also serves to illustrate my point about our beliefs and practices providing a

means of narrowing our focus on objective truths.

There is no denying that things exist which move under their own power. With

locomotors thus defined, this means that locomotors exist, uncontroversially. Now

suppose that this hypothetical philosopher thinks of herself primarily as a locomotor: the

qualities of hers that matter to her are her locomotive qualities. Further, she thinks that

all things capable of locomotion should be understood chiefly as locomotors. Were she

to wonder about what “our continuity conditions” are, she may well mean “locomotors”

by “our.” Indeed, the Locomotive Criterion sounds like an appropriate continuity

criterion for locomoting objects, understood as locomotors. If the question is “under

what conditions do we remain locomotors through time?”, then “so long as we retain the

ability to locomote” sounds like an objectively good answer. Our hypothetical

philosopher’s unusual belief that our defining quality is our ability to locomote is

subjective, but the continuity conditions of locomotors, once we have a clear definition of

‘locomotors,’ is objective. The subjective facts about our philosopher’s interests do not

change the objective facts about the continuity conditions of anything; they merely allow

us to hone in on a particular objective fact.

My emphasis on our actual beliefs and practices should not, then, be understood

as the mistaken assertion that our beliefs and practices can change the objective facts.

16

Rather, my aim here is to use our actual beliefs and practices as a guide to pick out the

subject that we are interested in the objective truths about its continuity conditions.

One might question the value of this approach, since it allows that the

intentionally-absurd Locomotive Criterion is an appropriate answer to a very similar

question. What separates the two is that there is no philosopher really so hung up on our

ability to locomote as this hypothetical one, whereas our beliefs and practices do reflect a

way that we think of ourselves and care about.

Suppose it were possible to track individual units of matter through time, and

someone articulated the present location of all the bits of matter that composed you ten

years ago. It would be uncontroversially and objectively true that those bits of matter are

identical to you ten years ago, but we would not take this as having any bearing on your

continuity. Why not? The identity of the matter that composes us simply isn’t what we

care about when it comes to our own continuity. The fact that we can make true

assertions about the continuity of that matter doesn’t make it relevant to our continuity

conditions, and what disqualifies it is that it isn’t what’s important in our continued

existence. If identity of matter was what mattered, then such a statement would be

informative about one’s continuity, but since it isn’t what matters, it isn’t relevant to our

continuity. Making any kind of meaningful assertion about our continuity involves

picking out, from a number of objective truths, which ones are relevant to the question

being addressed, and what we care about, subjective though it is, plays a determining role

in this.

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2.2 Actual Beliefs and Practices as a Basis of Continuity

As the previous section touched on, leading accounts of personal identity do not

attempt to conform with actual beliefs and practices concerning the continuity or identity

of persons. Olson prioritizes strict, numerical identity of organisms in his account even

as he acknowledges that many of the things we are concerned about when it comes to our

own survival may not coincide with numerical identity of organisms.6 David Hershenov

argues that the facts about what we would care about in a scenario where personal

identity is called into question are not indicative of anything about our survival.7 Parfit

argues that we are not what we believe, claiming that ordinary fears about outcomes we

believe we will not survive, though psychologically difficult or even impossible to

overcome, are irrational.8 The views they defend fall on opposite ends of the spectrum

on which most personal identity accounts fall, with Olson and Hershenov advocating a

physical continuity criterion of identity, while Parfit claims that any instance of our

psychologies, even one without any causal connection to us, makes for continued

existence. Thus, even proponents of sharply opposing views seem to agree on one thing:

our actual beliefs and practices are not relevant to our identity and/or continuity

conditions. Yet I’ve built a role for actual beliefs and practices into my inquiry. How

can this be justified?

6 Olson (1997), 44, 52-57.

7 Hershenov (2004), 454.

8 Parfit (1986), 279-280.

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First, it is worth reiterating that there are several distinct questions classed under

the ‘personal identity’ umbrella. Olson, for instance, is focused strictly on the numerical

identity of human animals. He acknowledges that, although we are persons as well as

animals, being a person and being an animal can come apart, and he focuses on us as

human animals based on his claim that we are human animals more fundamentally than

we are persons.9 His focus, then, is on answering the question of what makes for

numerical identity of human animals. My inquiry does not concern the numerical

identity of human animals, unless our actual beliefs and practices concerning personal

continuity happen to align with the numerical identity of human animals (I will later

argue that they do not). Thus, the fact that beliefs and practices do not have a role in his

inquiry does not show that there is no suitable role for them in mine, because we are

asking different questions.

It should also be acknowledged that allowing for beliefs and practices to guide us

is not uncommon in philosophy. Although such a move is rarely described as a

prioritization of actual beliefs and practices, it is not unusual to accept certain

propositions as true on the grounds that they seem intuitively correct, or for a view to be

considered less plausible on the grounds that it is strongly counterintuitive. When we do

so, when we accept a proposition because it seems intuitively true – which philosophers

certainly sometimes do – we are in effect accepting it on the grounds of our beliefs (or

perhaps a particular subclass of our beliefs). Treating certain of our beliefs as true,

absent a clearly articulated justification for those beliefs, is thus something that

9 Olson (1997), 30.

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philosophers do sometimes. Certainly, we are sometimes pressed to give up beliefs that

seem intuitively correct in the face of evidence against those beliefs, and failure to do so

is a mistake, but granting a role to our beliefs and practices, under the name ‘intuitions,’

is not inherently a problem.

The philosophers who defend views of personal identity that differ considerably

from our actual beliefs and practices do so not because our beliefs and practices have no

significance or value, but because they claim that other considerations make it impossible

to accept a view which fits well with our actual beliefs and practices. We depart from our

beliefs about a subject only with good reason. A view about any philosophical subject

that is wildly counterintuitive and has no justification for its rejection of our beliefs is not

likely to be highly regarded. What I am arguing is that, contra Olson, Parfit, and others,

it is possible to have a metaphysically coherent account of personal continuity which fits

with our actual beliefs and practices, and that the philosophical considerations against

such an account are not so insurmountable that such a view cannot be accepted.

Even allowing that there may be an appropriate role for beliefs and practices in an

account of personal continuity, there is still room for concern arising from the

arbitrariness of beliefs and practices. Beliefs and practices vary from time to time and

from culture to culture, but even if one focuses on a single culture at a single time, the

facts about that culture’s beliefs and practices are not necessary truths; the culture could

easily have had different beliefs and practices. Aside from the issues discussed in the

previous section about whether subjective facts like beliefs and practices have a role in

metaphysics, there is also the simple question of whether an account of personal

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continuity based on something so arbitrary and contingent as our beliefs and practices has

any interest or value.

The very feature that makes such an account contingent also makes it interesting

to us, however. For capturing our actual beliefs on the subject, such an account reflects

what we actually care about in a way that accounts which diverge from actual beliefs

cannot. Although ordinary people are not generally aware that there is any question

about personal identity, there is a relation in the neighborhood of personal identity that all

ordinary people do care about, even if they are not conscious of it. An ordinary person

cares about whether they will exist tomorrow in the way that matters to them, and will

not be heartened to learn that, for instance, a physical object numerically identical to their

body will exist tomorrow if the features of themselves that they value will be absent. By

diverging from our actual beliefs and practices concerning our own continued existence,

many accounts of personal identity fail to get at something that matters to us. That is not

a problem, of course; a great many legitimate philosophical questions don’t interest

anyone but philosophers. But given that ordinary people do have a stake in personal

continuity as evidenced by concerns about their own survival and the survival of others,

there is value in an account that targets those actual concerns in a way that other accounts

do not.

Proponents of views that diverge from our actual beliefs acknowledge this: Parfit

acknowledges that it may not be possible to get over the sense that the death of one’s

body and mind is bad, even if there is an identical mind elsewhere,10

and Olson

10

Parfit (1986), 279-280.

21

acknowledges that numerical identity of human animals may not coincide with what we

care about when it comes to survival.11

Even as they advocate accounts that reject our

ordinary beliefs and practices concerning our own continued existence, they acknowledge

that there is a fundamental pull towards certain beliefs that their own accounts cannot

accommodate. The views they describe, however well-defended, however theoretically

strong they are, do not track what we actually care about when it comes to our own

survival. And there is something we care about when it comes to our own survival.

Surely then, there is value in considering whether that set of beliefs and values we

actually hold could possibly be understood in a coherent way.

What I will do here is propose an underlying principle which supports the

majority of our existing beliefs and practices about our own survival, and explain away

the cases where it does not fit. The account I propose does not require strict numerical

identity, and it may not get at what we are essentially, if our beliefs and practices reveal

that our concerns about survival do not align with what we are essentially. But whether it

can properly be called an account of strict identity is less important than the fact that it

addresses a subject in which we do have a stake, something about which we already have

beliefs.

The preceding may show that we do care about the continuity conditions of what

we think we are. But this does not show that we should care about the continuity

conditions of what we think we are. Perhaps we are mistaken in our understanding of

ourselves. Why should it matter that we think of ourselves in a particular way? Humans

11

Olson (1997), 44.

22

have been and presumably still are wrong about very many things about the world around

us, including about ourselves and our own natures. Even if we determine what we

understand ourselves to be, and thus which continuity conditions we are interested in, this

still does not show that the continuity conditions of whatever we think we are have any

bearing on anything real, on anything but our own possibly-incorrect understanding of

ourselves. So why should we care about the continuity conditions of what we think we

are, when it may bear on nothing more than a misunderstanding of ourselves?

One reason is that we can learn and discover valuable things while operating

under assumptions which may not be accurate. If we assume that we are persons, for

instance, and in the process of expanding an account of our personal continuity based on

this assumption, find insurmountable problems, this provides some reason to re-evaluate

our original understanding of ourselves as persons. Assuming a premise for the sake of

argument is a perfectly respectable move in inquiry; seeing what follows from treating

our ordinary beliefs as true has the potential to either provide support for our ordinary

beliefs (if it leads to a cohesive theory which fits well with other beliefs that were not

assumed to be true) or to give us reason to try to understand ourselves differently, if

understanding ourselves in a particular way cannot fit with a metaphysically coherent

account of personal continuity. So if nothing else, granting that our existing beliefs are

true for the sake of argument is a legitimate philosophical move, and does not, in and of

itself, indicate an inappropriate or dogmatic attachment to our potentially incorrect beliefs

about ourselves.

23

There may also be a more substantive reason for us to care about the continuity

conditions of what we believe ourselves to be. The question of what we are, which in

turn determines what our continuity conditions are, is unlike many other metaphysical

questions in that some of the possible answers to that question are not mutually exclusive.

For example, it is uncontroversial that typical people are both human animals and

persons. Even those philosophers who insist we must be understood as one or the other,

when it comes to personal identity, do not deny that we are also the other. For instance,

although Olson argues that we are essentially human animals, he does not deny that we

are persons at all. He explicitly affirms that we are persons,12

and a significant element

of his argument deals with his claim that if something divisible from a human animal is a

person, the human animal must be a person too. Although he notes that there are

potential problems with any given understanding of personhood, his claim is not that

human animals are not persons, but the opposite: his claim is that if we are persons at all,

then human animals must be persons.13

Similarly, those who argue that we are

essentially our psychologies, essentially those traits that make us persons, do not deny

that each of us has a uniquely close relationship to a particular human animal such that, in

ordinary circumstances, we are virtually indistinguishable from the individual human

animals we are so linked to. Whatever one claims we are essentially, whether it is

persons, human animals, or minds or souls or anything else, it must also be

12

Olson (1997), 26. (As Olson notes on p. 6, he uses “people” rather than “persons,” but with the same

meaning as “persons.”)

13 Olson (1997), 102-109.

24

acknowledged that we qualify as persons in the philosophical sense of the term and are

uniquely linked to individual human animals (perhaps by being identical to them, perhaps

by some other relation). Thus, regardless of whether it is what we are essentially, typical

human animals are persons, even if our personhood is contingent and not an essential

feature. Thus, even showing that we are, for instance, essentially human animals does

not rule out the possibility that what we also genuinely are what we understand ourselves

as, if we were to understand ourselves as persons. The fact that we are both human

animals and persons means that even an airtight argument showing that we are essentially

human animals does not mean that we are wrong if we understand of ourselves as

something other than human animals. Because it is uncontroversially true that we are not

only human animals, an account of our continuity which addresses our continuity as

something other than human animals may well track something real, something that is

true of us, if only contingently true.

I’ve argued that we can accurately regard ourselves as both human animals and

something besides human animals, such as persons. How does this support my claim that

we should be interested in the continuity conditions of whatever we believe ourselves to

be? My claim is that, so long as what we believe ourselves to be is something that we

actually are, there is philosophical value in understanding our continuity conditions as

such. If we believed ourselves to be something completely baseless – for example,

supposing that dualism is false but we believed ourselves to be souls – then there would

be no value in discovering the continuity conditions of ourselves as souls, because the

account would not track anything real, only a mistaken understanding of ourselves. If,

25

however, what we believe ourselves to be is also something that we truly are, knowing

the continuity conditions of ourselves as that tracks something real. It may not track

what we are essentially, but it tracks something real about our nature, rendered significant

by our focus on it. The claim is, then, that if i) we understand ourselves as x, ii) are

correct that we are x, although we may not be x essentially, and iii) are interested in our

continuity conditions, then the continuity conditions of x is something we not only are in

fact interested in, but something we should be interested in. It is important because we

care about it and it is not a mere misunderstanding of ourselves. In other words, so long

as we understand ourselves as something we actually are, when we inquire about the

continuity conditions of ourselves as such, it is something real we are inquiring after, not

something that merely bears on an incorrect understanding of ourselves. This is different

from understanding ourselves as souls, to use the example from before, and thus taking

interest in the continuity conditions of souls. There are good reasons to question whether

souls exist, and if in fact there are no actual souls, then we cannot be souls, and so inquiry

into the continuity conditions of souls would not tell us anything about ourselves. If what

we understand ourselves to be is something that we actually are, then understanding our

continuity conditions as such will tell us something about ourselves.

Even if we are essentially human animals, and are what we believe ourselves to

be only contingently, we may believe ourselves to be something which we actually are.

As such, when we wonder about our own continuity conditions, we can legitimately be

interested in tracking either the continuity conditions of human animals or of what we

believe ourselves to be. If we are essentially human animals, then the continuity

26

conditions of human animals do track something relevant to us, but that does not mean it

is what we are after when we wonder about our own continuity conditions. There is no

reason we cannot understand ourselves as something other than human animals when we

inquire after our continuity conditions, and as such, there is no reason why we cannot

have in mind the continuity conditions of something else, and not human animals, when

we wonder about our own continuity conditions. When we speak of ourselves, we may

refer to the human animal, but since human animals are not the only things we are, they

are not the only things we can refer to when we speak of ourselves. Nothing about the

question of personal continuity entails that we must be concerned with the human animal

only when seeking an answer to that question. It is facts about our actual beliefs and

practices, our actual concerns, which dictate what we care about, what we mean, when

we wonder about our own continuity conditions. If our beliefs and practices reveal that

we regard ourselves as persons, as I will argue in the next section, then it is our actual

beliefs and practices, contingent though they may be, which dictate what matters to us in

the realm of personal continuity. An account which does not incorporate actual beliefs

and practices may well get at something real, but it does not get at what we care about.

Because there is something we care about in the area of personal continuity, because

there are beliefs we treat as true, it is valuable to grant a prominent role to beliefs and

practices to ensure that the resulting account tracks the thing that actually matters to us.

2.3 Using Actual Beliefs and Practices as a Starting Point

27

In the preceding sections, I’ve argued that, if we understand ourselves as

something which we actually are, then establishing the continuity conditions of what we

believe ourselves to be is valuable. I have not yet said much regarding what we do

believe ourselves to be.

It’s obvious that the question of what we are is closely related to the question of

what our continuity conditions are: what we are would seem to dictate what our

continuity conditions are, and if we do not have the continuity conditions associated with

some x, then we cannot be x. The risk of circularity here is high: it seems natural that

what we are dictates our continuity conditions, not the other way around, but it is difficult

to find grounds for defending a claim about what we are without reference to continuity

conditions.14

If we claim that we are (for instance) persons, because we have the

continuity conditions of persons, persisting in all and only the cases where a person

persists, and then proceed to argue that this shows that we have the continuity conditions

of persons, the circularity of the reasoning is obvious. One cannot insist that, in order to

say what our continuity conditions are, we must first ascertain what we are, and then rely

on claims about our continuity conditions are to support our claims about what we are.

To avoid this vicious circularity, one of the two questions must be answered

before the other, independent of assumptions about the answer to the other. If we can

determine what we are without reference to claims about our continuity conditions, then

we can legitimately determine our continuity conditions on the basis of what we are. But

if the only way to answer what we are is to refer to our continuity conditions, then the

14

Merricks (1998), 109-116.

28

question of what our continuity conditions are must come first, and without assumptions

about what we are.

My claim is that we regard ourselves as persons when it comes to our own

continuity. I have hinted at this, but have not yet said much to support this claim. There

are certainly contexts in which we are likely to regard ourselves as persons in particular,

rather than human animals or whatever else we may be. For instance, one might invoke

one’s personhood as evidence that one ought not to be mistreated in certain ways. Yet

there are other contexts in which we are likely to understand ourselves as human animals

rather than persons – for instance, when struck by the power of some urges. It is not clear

which sort of case, if either, bears on how we think of ourselves as existing throughout

time – whether what we care about, when we think of our futures, is the survival of

ourselves as human animals, as persons, or perhaps as both. In short, our existing beliefs

and practices about ourselves as a whole reveal that we understand ourselves as both

persons and human animals at times, and there does not seem to be much in our ordinary

beliefs about ourselves to tell us whether we speak of ourselves as persons or human

animals when we wonder about our own survival conditions.

If our beliefs and practices provide no answer about what we are without

depending upon claims about what our continuity conditions are, the question of what our

continuity conditions are must come first. But, in order to avoid circularity, and allow

our beliefs about our continuity conditions to support claims about what we are, we

cannot rely on any claims about what we are to support our account of what our

29

continuity conditions are. What can we rely on instead? What else do we have to base

an understanding of our continuity conditions upon?

Fortunately, there is something not reliant upon an assumption about what we are

to base our continuity conditions on: the transplant intuition (to borrow Olson’s name for

it). The transplant intuition is a belief about the continuity of ordinary people which is

revealed by considering hypothetical cases. If my brain were removed from my current

body and transplanted into another, brainless body, which of the two resulting people

would be me? The transplant intuition is the intuition that in such a case, the body into

which the brain was transplanted is me; the body that my brain was transplanted from is

no longer me.

How does the transplant intuition help untangle the circularity of the questions

about what we are and what our continuity conditions are? The transplant intuition

provides support for a claim about our continuity conditions which is not based on any

presuppositions about what we are, but based on a simple, pre-philosophical belief which

is commonly held. When an ordinary non-philosopher is asked where he will wind up in

a case where his brain is transplanted, whole and healthy, into another body, he does not

need to first stop and decide whether he is essentially a human animal, a person, a

Cartesian soul or something else entirely. He is likely to answer in accordance with the

transplant intuition without reflecting upon what he is, essentially or otherwise. In short,

then, the transplant intuition is an existing belief about our continuity conditions that does

not depend upon an answer about what we are. Thus, we avoid circularity if we base an

account of what we are upon the transplant intuition. From the conclusions we draw

30

there, we can legitimately expand our account of our continuity conditions. The

transplant intuition and what it reveals about our continuity conditions points the way

towards what we are, and in doing so allows us to further illuminate our continuity

conditions. Our acceptance of the transplant intuition as a claim about our continuity

conditions provides independent, non-circular grounds for establishing what we believe

ourselves to be in terms of survival, and an understanding of what we believe ourselves to

be allows us to expand our understanding of our continuity conditions based on that idea.

3 The Transplant Intuition

As indicated, the transplant intuition is the belief that when a person’s brain is

transplanted from one body to another, intact and without loss of function, the person

goes where his brain goes. The transplant intuition appears to be quite common; work in

personal identity suggests that the transplant intuition is the typical response to

hypothetical cases where a brain is removed from one body and transplanted, fully

functional and unchanged, into another body.

What does the transplant intuition tell us about our continuity in accordance with

our actual beliefs and practices? For starters, as an actual belief we have about our own

continuity, for an account of personal continuity to fit our actual beliefs and practices, it

ought to accommodate the transplant intuition. The transplant intuition, and what it tells

us about our beliefs about ourselves, allows us to surmise more about what we believe

ourselves to be, and in turn, to identify which accounts of personal continuity fit with our

actual beliefs and practices.

31

In the next chapter, I use the transplant intuition and other strongly-held beliefs

about ourselves to argue that the two main types of personal identity account cannot be

said to fit with our actual beliefs and practices. In the rest of this chapter, I defend using

the transplant intuition by addressing possible concerns regarding its prevalence, whether

it is specific enough to distinguish between accounts of personal identity, and whether

there are other, competing intuitions which are just as strongly held as the transplant

intuition.

3.1 Prevalence of the Transplant Intuition

How prevalent is the transplant intuition? Obviously, I cannot offer a concrete

answer to this question. The world population has not been polled on whether they

accept the transplant intuition. One might hesitate to use it as a starting point for my

argument, absent concrete evidence to support the claim that it is a widespread intuition.

However, I do not believe that this is the case; the assumption that the transplant intuition

is widely held is well-supported enough that it provides a suitable starting point for my

project.

How so? If there are not any concrete statistics about how many people hold the

transplant intuition, on what grounds do I claim that it is widely held? My support for

this claim comes from two sources: first, many philosophers assert that the transplant

intuition is widely held, even if they are defending a view which holds that the transplant

intuition is false; second, what little data is available about people’s intuitions concerning

32

personal identity and the transplant intuition supports the claim that the transplant

intuition is widely-held.

Regardless of the position they are defending, philosophers working in the

philosophy of personal identity frequently acknowledge the prevalence of the transplant

intuition. Olson, committed by the view he is defending to say that the transplant

intuition is false, says “I don’t reject that premise because it strikes me intuitively as

wrong. On the contrary: I share the Transplant Intuition with most of my readers.”15

Bernard Williams, ultimately rejecting such a view, acknowledges that cases where two

individuals are caused to have one another’s psychologies, through brain-transplants or

otherwise, seem to be cases of body-swapping, where the individual goes where his

psychology goes; because the brain is the carrier of the psychology, this means that the

individual goes where his brain goes when the brain is transplanted into another body.16

Judith Jarvis Thomson, though she claims that she cannot understand why anyone would

prioritize the brain above other internal organs in its role in identity or personal

continuity, acknowledges that “[i]t strikes many people as intuitively right”17

to say that,

in the case of a brain transplant where the body’s original brain is destroyed, the survivor

is the original owner of the brain, not the original owner of the body. These philosophers

all end up arguing that the transplant intuition is false, yet they acknowledge that it is

widely-held, thus making their own case more difficult by pointing out that their own

15

Olson (1997), 44.

16 Williams (2008), 179-185.

17 Thomson (2008), 158.

33

views fly in the face of such a widely-held intuition. If anyone were to argue that the

transplant intuition isn’t that common after all, isn’t that plausible after all, it should be

these philosophers, whose views go against it. Yet even these philosophers acknowledge

that it is a common belief and do not attempt to undermine this belief by claiming that it

is not so widespread as one might suspect. Support of the commonness of the transplant

intuition is just as prevalent among philosophers whose views are supported by it, as one

would expect.

Thus, philosophers working in the area of personal continuity tend to agree that

the transplant intuition is a common intuition, even when it would benefit their own

account to discount the significance of the transplant intuition. If there were reason to

doubt that the transplant intuition were all that common, these philosophers would

presumably make use of that doubt to undermine the claim that the intuition is common,

because it is easier going to defend a view against an uncommon belief than it is to

defend a view against an intuition so commonly held that it might even be regarded as

common sense. But across the board, whether it serves their theory or adds an obstacle

they must justify the rejection of, the transplant intuition is acknowledged as a widely-

held intuition. This provides reason to think that they are correct that the transplant

intuition is a widely-held intuition.

The prevalence of the transplant intuition is also supported by the little empirical

data we do have about intuitions concerning personal identity. Experimental philosophy

surveys by Shaun Nichols and Michael Bruno showed an “overwhelmingly clear”18

trend

18

Nichols and Bruno (2010), 299.

34

in support of the transplant intuition. Reproducing results from a prior study conducted

by Sergey Blok, George Newman, and Lance Rips, Nichols and Bruno found that

respondents said that an individual survives the destruction of his body if his brain is

transplanted into another body with his psychological features intact.19

These findings

support the claim that the transplant intuition is prevalent. To assert that an individual

can survive the destruction of his body by having his brain transplanted intact into

another body is to assert that the transplant intuition is correct. The individual lives on

because his brain lives on; this is precisely what the transplant intuition states. Thus, the

empirical data from Nichols and Bruno’s study, and from the similar study whose results

they reproduced, provides further evidence of the prevalence of the transplant intuition.

With support from the limited quantity of empirical data available, and from the

general consensus among philosophers working on the topic, it does not seem overly

presumptuous to claim that the transplant intuition is widely-held, bearing in mind the

obvious limitations concerning the populations reflected by this two sources (each

reflects only the intuitions common in present-day Western culture, etc.). I will

henceforth assume that the transplant intuition is widely-enough held that it can be

considered the prevailing pre-philosophical response to the type of hypothetical cases

used by philosophers working on personal identity, within the confines of the cultures

represented by those sources.

3.2 Problems With Using the Transplant Intuition

19

Nichols and Bruno (2010), 299-300.

35

If what I have argued in the previous section is correct, the transplant intuition is a

widely-held intuition concerning our continuity, and thus makes a suitable starting place

for an account of our continuity which prioritizes actual beliefs and practices. However,

even if one accepts both my claim that the transplant intuition is widely-held, and my

claim that actual beliefs and practices do make a suitable basis for an account of personal

continuity, there are still potential difficulties to contend with. In this section, I will

address some of the issues potentially arising from basing an account of personal

continuity on the transplant intuition.

3.2.1 Whole Brains or Parts of Brains?

One difficulty arising from using the transplant intuition is the issue of pinning

down exactly what the transplant intuition is. The transplant intuition tells us that a

person survives where her functioning brain survives, but which parts of the brain matter?

Dramatically different accounts of personal identity may agree that continuity of the brain

is what makes for survival, but differ on which part of the brain must continue to exist. If

the transplant intuition merely tells us that a person survives when his whole brain

survives, then it does not provide grounds to distinguish between very different accounts

of personal identity. If the transplant intuition is not more specific, it may prove useless

for identifying the account of personal identity which best fits our actual beliefs and

practices.

Initially, it may seem unlikely that it will be possible to determine whether the

transplant intuition only holds for whole brains or whether it applies to specific parts of

36

brains. After all, the average person probably cannot even name the major parts of the

brain like the cerebrum and the cerebellum, much less state their functions; as such, it

may seem unlikely that the average person would have intuitions concerning what

happens to one’s identity when you transplant not a whole brain but only part of a brain.

However, there is support for the notion that the transplant intuition deals not only

with whole brains, but with parts of brains, thus allowing the transplant intuition to serve

as a basis for separating different types of accounts of personal identity. As with the

transplant intuition taken generally, there are two sources of support for this claim: first,

philosophers who have something to gain by denying that the transplant intuition can

distinguish between parts of brains admit that it does distinguish between parts of brains.

Second, the little empirical evidence available from experimental philosophy supports the

claim that it is not the whole brain, but only certain parts, defined functionally, which

must be transplanted for our conclusions in the transplant intuition to hold.

As indicated previously, Olson’s view commits him to the claim that the

transplant intuition is false – but only when the transplant intuition concerns the

transplanting of the cerebrum, the part of the brain responsible for memory, language,

higher thought, and other psychological features and capabilities of the sort generally

associated with personhood. According to Olson’s view, the cerebrum is not necessary

for identity, but other parts of the brain not associated with psychological features but

with basic life-maintaining function are necessary for identity. As such, it would be

advantageous for his view if the transplant intuition dealt solely with whole brains, or

with an unspecified non-cerebrum part of the brain, because then his view would not go

37

against this common intuition but instead confirm the intuition. He could argue that a

transplanted brain makes for identity because a transplanted brain includes the parts

responsible for basic life-maintaining function. Olson specifically rejects this: he speaks

of the transplant intuition as the transplant of the cerebrum alone, rather than the whole

brain, and asserts that the intuitive pull that comes with the idea that we go wherever our

whole brains go should have exactly the same degree of intuitive pull as the idea that we

go wherever our cerebrums alone go. In short, he claims that the only reason we have the

transplant intuition for whole brains is because we have the transplant intuition for the

cerebrum.20

If there were any case to be made for the claim that the transplant intuition only

applies in the case of whole brains, or to non-cerebrum parts of the brain, it would be

prudent for Olson to make that claim, but he does not; he specifically characterizes the

transplant intuition as concerning the cerebrum, not the brain as a whole. It is of course

possible that Olson simply does not realize that ordinary people’s intuitions support a

variant of the transplant intuition that would provide support for his view. Absent some

reason to think this is the case, though, his failure to attempt to characterize the transplant

intuition in a way that would be advantageous to his theory provides some evidence,

though perhaps not much, in support of the claim that the transplant intuition draws its

intuitive pull from features of the cerebrum, not from features of the whole brain,

meaning that the transplant intuition does make distinctions between brain parts, and

specifically deals with the cerebrum and does not concern other parts. David Hershenov,

20

Olson (1997), 43-46.

38

who also argues against a role for psychological continuity in personal identity, asserts

that if our cerebrums were transplanted, the entity we would care about is the one that

receives our “upper brain,” not the one which keeps our original lower brain.21

A second source of support for the claim that the transplant intuition does

distinguish between parts of the brain, and concerns the cerebrum with other parts

irrelevant, comes from Nichols and Bruno’s study. As stated above, Nichols and Bruno,

compounding the evidence obtained in a previous similar study, found that those

surveyed believed that an individual can survive the destruction of his body when his

brain is transplanted into another body. However, their study also revealed that in

hypothetical cases where the brain transplant results in loss of memories, respondents

assert that the individual does not survive: they claimed that the individual does not

survive the transplant if his memories are lost in the transplant process.22

If a cerebrum is separated from the rest of the brain and transplanted into another

body (and appropriately attached to the other parts of the brain in the receiving body),

then there is no reason that the memories stored in the cerebrum should be lost in the

process. If, however, all of the brain but the cerebrum is transplanted into another body,

and the cerebrum is destroyed, the memories in the brain so transplanted will be lost;

memories are stored in the cerebrum and a transplant which involves the destruction of

the cerebrum is not a transplant in which the individual’s memories are preserved.

21

Hershenov (2004), 449-450.

22 Nichols and Bruno (2010), 299-300.

39

Thus, if we take the transplant intuition as correct, only brain transplants in which

the cerebrum is transplanted are identity-preserving. Other parts of the brain may or may

not be transplanted; assuming the truth of the transplant intuition only ensures that the

cerebrum must be transplanted in order for the individual to survive. Any transplant

which destroys the cerebrum, or even wipes it clean of memory, is not one which the

brain’s owner survives, if we take the transplant intuition as true.

Olson’s willingness to identify the transplant intuition with the transplant of

cerebrums alone, and the survey respondents’ tendency to highlight memory, a cerebrum

function, as necessary for identity, provide support for the claim that the transplant

intuition tacitly acknowledges distinctions between parts of the brain, and in fact

prioritizes the cerebrum on the grounds that it is the part responsible for preservation of

memory. Thus, the transplant intuition can, on the basis of this evidence, be understood

as an intuition concerning the transplant of cerebrums (and maybe other parts too). A

transplant of brain parts excluding the cerebrum is not a case the transplant intuition is

relevant to. This allows the transplant intuition to distinguish between different accounts

of personal identity, such as those that, like Olson’s, prioritize parts of the brain not

including the cerebrum, from those that prioritize psychological features, which may

require the cerebrum.

3.2.2 Competing Intuitions

A second concern is that the transplant intuition only has its intuitive pull in cases

where the individual has been led to it; the claim is that other, incompatible intuitions are

40

just as strongly held when the individual is not prompted towards the transplant intuition

by the language used to describe the case. If this is true, then it is not plausible to claim

that the transplant intuition provides a solid basis for an account of personal continuity

without giving equal credence to other views based on other intuitions just as strongly

held. If competing intuitions yield incompatible results, as they will, then this suggests

that a coherent account of personal continuity based on actual beliefs and practices is

impossible.

In “The Self and the Future,” Bernard Williams agrees that the transplant intuition

has considerable pull when puzzle cases are described in the way they usually are. The

reader is asked to envision a case in which two individuals, A and B, undergo a procedure

which causes A to believe himself to be B, behave in ways characteristic of B, seem to

recall from the first-person events which happened to B and not to A, and so on; in short,

A takes on all the psychological qualities of B. The reverse is also true: B takes on the

psychological qualities of A. Williams does not place many constraints on the nature of

this procedure, but he does stipulate that “there should be some suitable causal link”23

between the individual recalling some experience and the body which had that

experience, if the memories transferred are to be considered genuine memories.

Although it is not the only way for this condition to be secured, Williams notes that one

way that this condition can be met is if the procedure which causes the seeming

psychology-swap is a transplant of A’s brain into B’s body, and B’s brain into A’s body.

Because other ways this result could be achieved are not relevant to the transplant

23

Williams (2008), 180.

41

intuition, I will suppose here that the way this reversal of psychological features is

achieved is by the transplanting of A’s brain into B’s body and the transplanting of B’s

brain into A’s body.24

The anticipated reactions of A and B to various things that might

occur after the procedure provide support for the transplant intuition. A and B are likely

to reason as though they will be swapping bodies. If one of the two bodies will be

tortured following the procedure, A will reason that he should wish that B’s body comes

to no harm, since he does not want harm to come to him, and the occupant of B’s body

will think of himself as A. In short, the natural responses of A and B seem to affirm the

transplant intuition.25

So far, so good; Williams here affirms the intuitive pull of the

transplant intuition.

The potential difficulty arises when the same case is described differently.

Williams asks the reader to imagine they are being told of a horrific procedure which will

occur in their near future:

Someone in whose power I am tells me that I am going to be tortured

tomorrow. I am frightened, and look forward to tomorrow in great

apprehension. He adds that when the time comes, I shall not remember

being told that this was going to happen to me, since shortly before the

torture something else will be done to me which will make me forget the

announcement. This certainly will not cheer me up… that will still be a

24

Williams states that such a transplant is “One radical way of securing the condition in the imagined

exchange” but that “we may not need so radical a condition” if it is possible to extract psychological

information from one brain and alter another to bear it. Williams (2008), 180.

25 Williams (2008), 179-184.

42

torture which, so long as I do know about the prediction, I look forward to

in fear.26

The torturer goes on to explain that not only will you be caused to forget the

announcement of torture, you will also be caused to forget everything else, too: you will

have none of the memories which you currently have, and will instead have a completely

different set of impressions about the past. This, too, will not cheer up the unfortunate

reader; the loss of one’s memories is, Williams asserts, yet another misfortune, not a way

to avoid torture, and being caused to have other seeming memories put in their place does

not change this.27

Williams’s second case, then, is one in which the reader is made to think it quite

plausible that she will look forward in fear to her torture, even though her memories will

be erased and replaced beforehand; knowledge that her memories will be replaced first

does not make it any better that torture is coming. The difficulty for the transplant

intuition arises from the fact that the second case Williams has described can plausibly be

understood as identical to A and B’s situation, but with the reader put into the position of

A or B. In the A and B situation, it seemed that A and B switched bodies, so if A could

prevent torture to B’s body after the procedure by having A’s body tortured instead, he

ought to, because he will be the occupant of B’s body after the procedure. This is what

the transplant intuition tells us. But Williams’s second case makes it seem that the reader

ought to prevent torture of her body if she can, regardless of whether a memory-replacing

26

Williams (2008), 185-186.

27 Williams (2008), 186-187.

43

procedure happens first. If the reader will dread her future torture and find no peace in

the knowledge that her memories will be replaced first, then A ought to dread the torture

of A’s body, even though when the torture occurs, A’s body will bear B’s memories, and

not bear A’s memories. The reader’s situation is exactly like A’s situation, but in the first

case we think that A ought to prefer the torture of A’s body over the torture of B’s body

after the procedure, because A will reside in B’s body at that time; in the second case, we

think that the reader ought to prefer the torture of anyone else over the torture of her

body, regardless of what happens to her memories between now and the torture. The two

cases seem to be identical, but yield contradictory intuitions.28

If the transplant intuition

holds when a single case is described in one way and an incompatible intuition holds

when the same case is described in another way, it seems that our intuitions are too easily

manipulated by the way the case is described to provide a reliable basis for an account of

personal continuity.

How can I defend my reliance upon the transplant intuition if an incompatible

intuition holds just as strongly when the same case is described differently? I will argue

that the transplant intuition is in fact more strongly-held; the contradictory intuition

yielded by Williams’s second case is brought about by leading the reader to it, contrary to

Williams’s claim that the response to the first case is a result of the reader’s intuitions

being led astray.

Williams acknowledges that there are potentially relevant differences between his

two descriptions of the case. The case of A and B is in the third person, while the case of

28

Williams (2008), 187.

44

the reader asks the reader to imagine the case in the first person. Williams seems to

suggest that it is the first-person case, rather than the third-person case, which gets a more

accurate reaction, allowing the reader to realize that pain is something to be dreaded

regardless of what psychological changes come in between, whereas the third-person

cases does not allow for this realization.29

The claim, then, appears to be that the

difference between the first-person and third-person descriptions is relevant, but our

reaction to the first-person case is more telling.

Nichols and Bruno’s study undermines this conclusion, however. To demonstrate

this, they began by reproducing the results from Blok et al.’s study, using a case similar

to the one in that study. In that study, respondents are told that a badly-injured man, Jim,

has his uninjured brain transplanted into a “stock body” (grown in a lab, complete but

without a brain), while the injured body is destroyed. The brain is hooked up correctly

into the stock body; the transplant recipient is alive and functioning, and the brain retains

all the memories it had before being transplanted into the stock body. With the case thus

described in the third-person, Nichols and Bruno found, as Blok et al. had, that

respondents thought that the brain owner survived so long as his memories were intact

following the procedure. The same case was then described with first-person pronouns

used instead of proper names. In the first-person variant of the case, respondents

indicated that they would survive so long as their memories remained intact in the brain

after it was transplanted into the stock body. There was no significant difference in

responses depending on whether the case, identical in all other ways, was described in the

29

Williams (2008), 187-188.

45

first person or the third person. This suggests that it is not a difference between first- and

third-person description which causes the different intuitions between Williams’s two

cases.30

The second potentially relevant difference between Williams’s two cases is that in

A and B’s case, we know that A’s psychological features do not cease to exist when they

are removed from A; rather, they are moved into B. In the reader’s case, we are not told

what becomes of the reader’s psychological features; we simply know that they are gone

from her head. Williams argues that our intuitions are led astray in A and B’s case by the

fact that the psychological features are present elsewhere. Our intuitions are more

accurate in the reader’s case because the reader’s concern is with what will happen to her,

and what happens to someone else undergoing something similar is not relevant: “My

selfish concern is to be told what is going to happen to me, and now I know: torture,

preceded by changes of character, brain operations, changes in impressions of the past.”31

However, as described, this is question-begging. The torture only can be accurately

described by the reader as “what is going to happen to me” if body-swapping has not

occurred. To characterize the torture as something that will happen to the reader is to

assume that body-swapping has not occurred, when of course the question of whether

body-swapping has occurred is one facet of the very thing up for inquiry. Thus, Williams

cannot argue that our intuitions in the second case, contra the transplant intuition, are

30

Nichols and Bruno (2010), 299-300.

31 Williams (2008), 189.

46

more accurate because of the irrelevance of the other person, because the other person is

only irrelevant if body-swapping has not occurred.

Nichols and Bruno’s data also provide reason to doubt Williams’s claim that our

intuitions about the reader’s case are more accurate because it is not specified what

happens to the reader’s memories: in their study, as well as the one which they

reproduced results from, “all that is specified is that the memories are erased. There is no

hint that the memories are recreated somewhere else. Yet the responses participants gave

accords with a psychological criterion that holds that memory-preservation is necessary

for persistence.”32

In other words, respondents who had a case described to them where

an individual loses their memory and are not told it is recreated elsewhere still respond in

accordance with the transplant intuition, thus undermining Williams’s claim that it is the

knowledge that a psychology is recreated elsewhere which makes us respond in

accordance with the transplant intuition.

Thus, neither of the two most readily apparent differences between Williams’s

two cases provides reason to think that our intuitions are more accurate for the reader’s

case than they are for A and B’s case. In fact, the empirical data available suggests the

contrary. Respondents said that a person survives a brain transplant if the memories are

intact and does not survive if the memories are not intact, even though there is no

mention of recreating the memories elsewhere. In the reader’s case, her memories are not

intact at the time of torture; going by the respondents’ answers, this suggests that the

transplant intuition might even hold in the reader’s case if it were not described in such

32

Nichols and Bruno (2010), 300.

47

an emotionally evocative way. This suggests that it is the response to the reader’s case,

and not the response to A and B’s case, which leads one to a faulty intuition.

It is also worth noting that, as Williams describes the two cases, one is described

in a question-begging way and the other is not. Williams claims that the second case, the

reader’s case, is the one which yields the more accurate intuition, but it is the second

case that is described in a question-begging way. The description of A and B’s case is

not question-begging: the phrasing of the scenario does not assume an answer to where A

and B wind up. Only A and B’s possible answers assume anything about where they will

be after the procedure. The description of the reader’s case does have question-begging

language built into it: the torturer tells the reader that she will be tortured tomorrow,

which is only true if body-swapping does not occur. These instances of question-begging

language in the reader’s case give reason to think that the misleading intuition is the one

brought about by the reader’s case, not the transplant intuition brought about by A and

B’s case.

Another component of Nichols and Bruno’s study provides further support for

this interpretation of the competing intuitions. For this part of the study, respondents

were asked to imagine a case which is a variant on Williams’s reader case: an individual

will undergo a treatment that will permanently destroy his distinctive mental features,

including memory, personality and so forth. Afterwards, he will undergo a series of

painful injections. Whether this case was described in the first or third person,

respondents asserted that the individual would feel the pain of the injections: 75% agreed

that “[w]hen the doctors administer the series of shots, you will feel the pain” in the first-

48

person case, and 72% agreed with the equivalent statement in the third-person case.33

This supports Williams’s claim about what our intuition tells us about such a case, and in

conjunction with the results of their other survey about brain transplant and memory,

confirms that there do appear to be competing intuitions.

Nichols and Bruno note that these results support Williams’s claim that certain

ways of describing or framing the situation can lead the respondent to an intuition she

would not otherwise be inclined towards. However, they also suggest that their version

of the case gives us reason to think it is the framing of the reader’s case, not the framing

of A and B’s case, which involves leading the respondent to an answer: “In [the reader

case’s] frame, there seems to be a demand to respond that I would feel the pain. After all,

if I am not going to feel it then who is?”34

Such cases make it apparent that pain will be

felt, and when pressed to identify the victim of that pain, the respondent has no better

answer than to claim that it is the person who occupied that body (at least) until their

memories were removed. Since this response is the result of being pressed for an answer

when none is at hand, it is plausible to argue that the transplant intuition is the more

firmly-held intuition, and thus provides a more suitable basis for a continuity account.

Thus, although it is true that similar cases described differently can lead to

intuitions incompatible with the transplant intuition, there is reason to think that the

transplant intuition more accurately reflects our beliefs about our own identity, since the

cases which yield competing intuitions look to be more biased than cases which yield the

33

Nichols and Bruno (2010), 300-303.

34 Nichols and Bruno (2010), 304.

49

transplant intuition. As such, I will consider the transplant intuition a suitable basis for

understanding our beliefs and practices concerning our own continuity and/or identity.

50

Chapter 2: Considering the Contenders

1 Evaluation Criteria

It is perhaps worth briefly reiterating my goals here: I mean to consider whether

there is a metaphysically coherent understanding of personal continuity which accords

with our actual beliefs and practices. In this chapter, I will consider several accounts of

personal identity, chosen both for their representativeness and their prominence, and

evaluate whether they fit with our actual beliefs and practices concerning the continuity

of persons.

In the previous chapter, I argued that the transplant intuition provides a suitable

starting point for working out a continuity account based on our actual beliefs and

practices. I argued that the transplant intuition is more strongly held than competing

intuitions, suggesting that an account of personal identity which is incompatible with the

transplant intuition is a poor fit for our actual beliefs and practices. However, the

transplant intuition is not the only intuition we have about our own persistence, and the

role of metaphysical coherence should not be overlooked: a theory which is logically

incoherent, or requires commitment to wildly implausible metaphysical claims, is of little

use. My aim is not to document what we believe about our own persistence conditions –

that would be, as Olson noted, mere anthropology, not metaphysics. My aim is to give an

account of personal continuity which respects the role our beliefs and practices may

plausibly have without sacrificing metaphysical coherence. An account which

accommodates every nuance of belief but is metaphysically incoherent fails to satisfy my

51

conditions; some sacrifice of fit with beliefs for the sake of metaphysical coherence may

be necessary.

As I consider a variety of accounts of personal identity, I evaluate their fit with

actual beliefs and practices, including but not limited to the transplant intuition, as well as

whether they face insurmountable metaphysical difficulties. I take the other intuitions I

cite to be in need of little defense; they are fairly obvious claims along the lines of ‘it is

(generally) bad to die.’ Three broad categories of views are discussed here: non-

reductionist views, which argue that personal identity consists in a further fact beyond

mere continuity; psychological-continuity views, which argue that personal identity

consists in the continued existence of one’s psychological features; and physical-

continuity views, also known as biological views, which argue that personal identity

consists in the continued existence of one’s physical body without regard for one’s

psychological features. I argue that views falling into each of these three categories

either require acceptance of wildly counterintuitive claims that cannot be explained away

or are metaphysically unacceptable. My intent is for my positive account, discussed in

the next chapter, to avoid the pitfalls these views are subject to while retaining their best

qualities.

2 Non-Reductionism

As has been mentioned, accounts of personal identity are often divided into those

which prioritize psychology continuity and those which prioritize physical continuity.

However, both psychological and physical continuity accounts are reductionist, while

52

some accounts of personal identity are non-reductionist. In personal identity,

reductionism and non-reductionism are distinguished by whether they claim that personal

identity is reducible to other facts, such as physical or psychological continuity, or that

personal identity is a further fact, distinct from continuity. Parfit characterizes

reductionist accounts as those which claim “that the fact of a person’s identity over time

just consists in the holding of certain more particular facts,” namely whether physical or

psychological continuity is maintained to a sufficient degree, and perhaps also “that these

facts can be described without either presupposing the identity of this person, or

explicitly claiming that the experiences in this person’s life are had by this person, or

even explicitly claiming that this person exists. These facts can be described in an

impersonal way.”35

Accounts which reject both of these claims are non-reductionist.

Many non-reductionist accounts of personal identity hold that we are entities

which exist separate from our bodies or brains, and our continuity conditions are

determined by facts about these separate entities, not by the continuity conditions of

anything relating to our bodies or brains. Cartesian Dualism, according to which we are

purely mental entities closely linked to but distinct from specific physical brains and

bodies, is the most obvious form of this type of non-reductionism; as purely mental

entities, neither physical nor psychological continuity bears on our continued existence

through time.

A non-reductionist need not claim that we exist separately from our bodies or

brains, however. Some accounts of personal identity deny that we are to be understood

35

Parfit (1986), 210.

53

as distinct from our bodies or brains, while maintaining that personal identity is a further

fact, not just a matter of physical continuity, psychological continuity, or some

combination thereof, meaning that these views are non-reductionist.36

Following Parfit, I

will refer to this sort of approach as the Further Fact view.

2.1 Separate Entities

The most prevalent form of non-reductionism about personal continuity is the

view that we are entities distinct from both our physical bodies and our physical brains.

Such views vary in what they claim we are, but for my purposes here it is not particularly

relevant; many claim that we are a non-material entity, such as a Pure Cartesian ego, or

some more theistic variant like a soul or spirit. The view that we are something distinct

from our bodies and brains need not be non-materialist, however – it could assert that we

are something physical which is nonetheless not body, brain, or a part of either.37

For

simplicity’s sake, I will speak of egos only, but what I say should apply equally well to

any of the other things we might be according to such a view.

If we are something distinct (and non-supervening) from our bodies or brains,

then our personal continuity is not determined by any facts about the continuity of either

body or brain, and thus both physical continuity and psychological continuity are neither

necessary nor sufficient for the continued existence of a given individual. Facts about the

ego are what underlie truths about our continuity, if we are egos. In an ordinary case, for

36

Parfit (1986), 210.

37 Parfit (1986), 210.

54

instance, what makes it true that that child was me, and not some other, is the fact that

that child has the same Cartesian ego which I have now. If I didn’t have that ego, then it

would be false that that child was me.

The separate entities view has one significant advantage it shares with any other

non-reductionist view: because personal continuity comes from facts about a Cartesian

ego or other separate entity, the problems which arise from the possibility of dividing the

body or brain do not arise. We can halve a brain and put each half into its own body,

resulting in a case where it seems that one person has become two people, a scenario

which results in difficulties for reductionist accounts of identity. Because identity is

transitive, and the two halves are non-identical, it cannot be the case that the original

person is identical to both of the resulting people. The halves each have an equally good

claim on being the original, so there is no good justification for saying that the original is

identical to one of the two but not to the other. And yet it seems bizarre to say that the

original ceases to exist simply because there are two equally good candidates for being

identical to the original, particularly since there are actual cases of people who survive

the destruction of half of their brains, living on without any changes so radical we think

of them as a different person.

Cartesian egos, being indivisible, make personal identity satisfyingly all-or-

nothing. In the halving case described, the original would be identical to whoever has the

same ego as the original. If one half has it and the other does not, then the original is

identical to the half that has it, and not identical to the half that does not. The ego is

indivisible so it cannot be split between the two. If the ego ceases to exist upon the

55

division of the original, then neither of the two is identical to the original. The non-

reductionist approach ensures that there is a definite answer to questions of personal

identity, which seems like a very natural belief. The original in the case described would

surely be puzzled to learn that it is indeterminate whether she will exist at a time past her

division. Identity seems like it should be all-or-nothing, with a determinate answer in any

given situation. The separate entity view accommodates this belief.

The separate entities view can also readily accommodate the transplant intuition,

via the claim that in cases where the brain or part of the brain is transplanted from one

body to another, the Cartesian ego moves from one body to another. It could be claimed

that it does so because the ego is somehow tethered to a given brain, or it could be said

that it simply occurs by fortuitous coincidence. In either case, the separate entity view is

able to assert that the transplant intuition is true by asserting that the thing a person is,

moves bodies when our intuition tells us that she moves bodies.

By now the general trend should be apparent: the separate entity view is able to

accommodate our beliefs quite neatly by asserting that the ego behaves in a way that

corresponds with our intuitions about our own continuity. Although it makes the separate

entity view appealingly flexible, it also reveals a significant weakness on the part of the

view: what evidence is there to support the claims that could be made by a proponent of

this view? Why should we think that me-at-ten has the same ego as me-now, besides that

we already believe that me-at-ten and me-now are the same person? Why should we

think that the ego may switch bodies during a brain transplant, beyond that our intuitions

tell us that the person switches bodies? There does not appear to be any justification for

56

thinking that the ego behaves in this particular way, besides that we already think

personal identity behaves in that way. We think that child had this ego only because we

already think that child is identical to me; we do not have any reason not related to

personal identity to think that that child and I have a Cartesian ego in common. We have

no good reason to think that an ego may move during a brain transplant beyond our prior

intuition about what happens during a brain transplant. If we explain what happens

during a brain transplant in terms of personal identity, and explain the criterion of

personal identity by reference to what happens during a brain transplant, nothing is

revealed. Only by presupposing personal identity can we make any claim about what

does happen during a brain transplant. So it appears that the only evidence to support

claims about in whom a given ego can be found presupposes personal identity. If this is

the case, then the separate entity view only fits our beliefs so well because it bases its

claims on our beliefs, thus rendering it unsuitable to provide support for our beliefs.

As Parfit notes, it is not beyond imagining that we might have been Cartesian

egos, that evidence could support the view without circularity. Parfit imagines a scenario

where a great many people are found to have memories which appear to be from lives not

their own, but rather past lives: they have knowledge which they could not have obtained

by any means in their present lives. It is found that they have no parts of body or brain in

common with the past people whose memories they seem to bear, and that while certain

types of brain damage completely eliminate these memories of past lives, other types of

brain damage do not affect them at all; no type of brain damage diminishes but does not

eradicate these past memories. With this sort of evidence, it could be reasonable to

57

suppose that what unites these present people with the memories of past people is a

common part, but not a part of body or brain: it could be a Cartesian ego (or some other

separate entity), and we may come to regard ourselves as identical to these Cartesian

egos.38

If this were the case, we might have evidence, in the form of those memories, to

make assertions about the behavior of given egos. However, because we do not have any

evidence that supports the existence of Cartesian egos, much less any non-circular

grounds to make assertions based on how Cartesian egos react to various hypothetical

personal identity problem cases, the separate entity view is not plausible as an account of

personal continuity compatible with our beliefs and practices. It accommodates our

existing beliefs only by circular reasoning, and suffers in comparison even to other non-

reductionist accounts, for introducing the high metaphysical costs associated with

positing the existence of Cartesian egos or whatever other separate entity we might be.

As such, I leave this view aside.

2.2 The Further Fact View

A non-reductionist about personal identity need not claim that we are entities

distinct from our bodies or brains. It is also possible to claim that personal identity

consists in a further fact without asserting that we are distinct from our bodies. It is this

sort of view which Williams suggests in his “The Self and the Future.” As the discussion

in the preceding chapter showed, Williams argues against psychological continuity as

38

Parfit (1986), 227-228.

58

either necessary or sufficient for identity, claiming that a person will and should fear

future pain, regardless of what psychological changes she may undergo prior to the

occurrence of that pain. His claim is not simply that physical continuity is necessary or

sufficient for personal identity, however: Williams’s view is non-reductionist, as he

rejects the possibility of indeterminacy of personal identity, whereas a view which calls

for physical continuity as the criterion of personal identity allows for indeterminacy,

since physical continuity is a matter of degree.

Williams describes a progression of cases similar to the reader’s case, from one in

which A has amnesia induced to one where A’s psychology is replaced by B’s and B’s is

replaced by A’s. His claim is that A clearly should fear pain that will follow his amnesia

in the first case, and that there is no justification for placing a line between any of the

other cases, as the qualities which distinguish the cases are not the sort of things that

should affect identity. Thus, although our intuitions tell us that A need not fear the

torture of his body in the final case where A and B seem to swap bodies, A should fear

that pain even in this case, because no body-swapping actually occurs; it is A who will

feel that pain, just as in the first case. Williams notes that it can be argued that there is no

need to draw a line between cases, but rejects that approach as “baffling” in this

particular case by raising the issue of how A ought to regard the future torture of his

body. A will have no idea how to regard the future torture of his body if it is

indeterminate whether it will be he who experiences the pain that body is subjected to.39

39

Williams (2008), 190-193.

59

This indeterminacy is different from other cases of indeterminacy which are

comprehensible: Williams contrasts A’s situation with a case where he is a member of a

group of five, and knows that one of the five will be tortured. In the latter case, his

emotions will be affected by the indeterminacy of whether it is he or someone else who

will be tortured, but the indeterminacy is not like the indeterminacy A faces. If Williams

fears his torture in the one-of-five scenario, it is because he is imagining that the result is

that it is he, and not one of the other four, who is tortured. If Williams does not fear his

torture in that scenario, it is because he is imagining that it is one of the others who is

tortured. The conflicting emotions result from distinct possible outcomes: he fears his

torture, and does not fear a case in which he is not the victim of the torture. This is unlike

A’s situation, where the conflicting fear and lack of fear concern the very same case,

rather than two distinct outcomes. A’s body is tortured, but even as the torture occurs it

remains indeterminate whether it is A who is experiencing the pain, if borderline cases

are permitted. 40

Williams concludes that it is not plausible to allow for borderline cases,

or to allow convention to provide a determinate answer in borderline cases. Identity must

be all-or-nothing for Williams, and thus we can infer his commitment to a non-

reductionist account, since reductionist accounts only avoid indeterminacy by drawing

lines, which Williams also rejects.

The advantages and disadvantages of the further-fact view of personal identity are

similar to those of other non-reductionist accounts: identity is always determinate, which

fits well with very natural beliefs about ourselves. The transplant intuition can be

40

Williams (2008), 192-194.

60

accommodated, although whether it is will depend on the specifics of the view, which

Williams does not articulate. With regard to disadvantages, the further-fact view fares

slightly better than the separate-entity view, in that it is able to avoid some of the

metaphysical baggage associated with the claim that we are separate entities. However,

we lack evidence to support this view, just as we lack evidence to support the separate

entities view, and the claim that there is a further fact about what we are leaves many

questions unanswered. What is this further fact? How do we know when it holds,

without being circular? Answering these questions will leave the further fact view

saddled with nearly all of the difficulties of the separate entity view, making it

unappealing as an answer to the question I focus on here.

3 Psychological Continuity Views

In this section, I consider views which claim that our continuity requires

psychological continuity and does not require physical continuity. Views of this sort date

back to John Locke’s Essay Concerning Human Understanding, where Locke advocates

a simple version of a psychological continuity view, claiming that the existence of a

consciousness that recalls past actions as one’s own makes for the continuity of a person

– simply put, that memory makes for personal identity. Although its simplicity leaves it

open to criticisms later psychological continuity accounts avoid, it is notable for being a

simple formulation which calls for psychological continuity while rejecting the need for

physical continuity, as well as for being possibly the first account of personal identity, as

61

it is understood today, of any kind.41

Thus, it serves as a good example of the simplest

form of psychological continuity account.

For a more contemporary and better-developed psychological continuity account,

I focus on Derek Parfit’s account as described in his Reasons and Persons. Its

prominence in the literature of personal identity, as well as its explicit rejection of any

role for physical continuity, make it an ideal candidate for determining whether a view

that calls for psychological continuity and ignores physical continuity can satisfactorily

fit with our pre-philosophical beliefs about our own continuity.

2.1 Locke’s Memory-Based Account of Personal Identity

Broadly, Locke’s claim about our continuity is that personal identity consists in

continuity of memory. We can be identified with our consciousnesses, he claims, and

memory is what makes it the case that a consciousness at some past time is the same

consciousness as one that exists in the present. Locke’s account is explicitly reductionist:

he claims that even if there is some nonmaterial substance in each of us, we cannot be

identified with this nonmaterial substance if it is separable from consciousness.

Locke argues for a distinction between the terms ‘man’ and ‘person,’ stating that

the former (Locke’s use seems to be equivalent to contemporary use of the term ‘human’)

should be understood as a term used to pick out a particular sort of living organism,

namely an animal, while the latter should be understood as “a thinking intelligent being,

that has reason and reflection, and can consider itself as itself, the same thinking thing, in

41

Perry (2008a), 6.

62

different times and places; which it does only by that consciousness which is inseparable

from thinking, and, as it seems to me, essential to it.”42

Because the two terms pick out

different sorts of things, it is unremarkable that the conditions under which we claim that

some x is the same (hu)man as some y are different from the conditions under which we

claim that some x is the same person as some y. Locke asserts that the identity conditions

of a man are the same as the identity conditions of any other animal: “the identity of the

same man consists; viz., in nothing but a participation of the same continued life, by

constantly fleeting particles of matter, in succession vitally united to the same organized

body.”43

However, he rejects the identity conditions of man as the proper subject of an

inquiry into personal identity, arguing that persons, being defined by consciousness, have

identity conditions based on continuity of consciousness:

For, since consciousness always accompanies thinking, and it is that which

makes ever one to be what he calls self, and thereby distinguishes himself

from all other thinking things: in this alone consists personal identity, i.e.,

the sameness of a rational being; and as far as this consciousness can be

extended backwards to any past action or thought, so far reaches the

identity of that person; it is the same self now it was then; and it is by the

same self with this present one that now reflects on it, that that action was

done.44

Locke claims that it is irrelevant to the matter of personal identity whether a given

consciousness is composed of a single thinking substance or not. He claims that so long

as the consciousness is one and the same, a change of substance is as irrelevant to identity

42

Locke (2008), 39.

43 Locke (2008), 37.

44 Locke (2008), 39-40.

63

as a change of clothes is to identity of a human, stating that the same consciousness can

unite disparate substances so that they are the same person. He defends this claim by

noting that the body a particular consciousness is “united to” may lose parts without

affecting the identity of the consciousness united to that body – thus the substance that a

consciousness exists in can undergo change without causing a change in the

consciousness.45

Locke explicitly rejects a role for both physical continuity and for the continuity

of an immaterial thinking substance as components of personal identity. He states that if

an immaterial thinking substance has belonged to Socrates, for instance, in the past, but

the consciousness of the present owner of the substance does not extend to the actions of

Socrates, the present owner of the substance cannot be considered to be Socrates.

Without consciousness uniting them, it makes no difference whether a single immaterial

thinking substance existed before its current user’s existence. Consciousness alone, and

not the things that may bear consciousness, such as the physical body or an immaterial

thinking substance, is what personal identity tracks.46

The most readily apparent difficulty for Locke’s view is that its heavy emphasis

on consciousness and memory seems to lead to difficulties for ordinary cases of personal

identity, given that lapses in consciousness and memory are not abnormal. To the

contrary, someone who was always conscious and never forgot anything would be

45

Locke (2008), 41.

46 Locke (2008), 43-44.

64

exceedingly abnormal. How can Locke’s view accommodate the fact that such lapses are

a normal part of human experience?

It may be that Locke intends to resolve this difficulty by calling for personal

identity to be determined by what consciousness could be extended to, rather than what

consciousness is actually extended to. For example, he states that “as far as this

consciousness can be extended backwards to any past action or thought, so far reaches

the identity of that person”47

and that a self “will be the same self, as far as the same

consciousness can extend to actions past or to come”48

(emphasis added in both quotes).

Thus, one might think, as Perry proposes,49

that Locke aims to avoid these difficulties by

pointing out that, although a sleeping person may not in fact remember the things that the

waking person does, and vice versa, it is nonetheless possible in principle for a sleeping

person to recall any given memory of the waking person’s, and vice versa. With this

approach it may be possible to avoid the counterintuitive and metaphysically clumsy

conclusion that we go out of existence when we fall asleep, returning to existence when

we wake, and that we share our bodies with another person who is present only when we

sleep.

However, it isn’t obvious that Locke himself is committed to this possibilities-are-

sufficient approach to personal identity. In arguing that a single immaterial substance

may comprise two distinct persons, Locke describes the following case:

47

Locke (2008), 39.

48 Locke (2008), 40-41.

49 Perry (2008a), 16.

65

Let any one reflect upon himself, and conclude that he has in himself an

immaterial spirit, which is that which thinks in him… let him also suppose

it to be the same soul that was in Nestor or Thersites, at the siege of

Troy…, which it may have been as well as it is now the soul of any other

man: but he now having no consciousness of any of the actions either of

Nestor or Thersites, does or can he conceive himself the same person with

either of them? Can he be concerned in either of their actions? attribute

them to himself, or think them his own, more than the actions of any other

men that ever existed? So that this consciousness not reaching to any of

the actions of either of those men, he is no more one self with either of

them, than if the soul or immaterial spirit that now informs him had been

created, and began to exist, when it began to inform his present body,

though it were ever so true, that the same spirit that informed Nestor’s or

Thersites’ body were numerically the same that now informs his.50

Locke’s argument is that because the individual (call him Bob) does not have any

conscious recollection of the actions of Nestor or Thersites as his own, he cannot rightly

be considered the same person, to share a self, with Nestor or Thersites. But there is

potential trouble for Locke here: he stipulates that Bob does not recall the actions of

Nestor or Thersites, but is it certain that he cannot? The trouble is that to determine what

one could possibly recall that one in fact does not, we need something to ground that

modal claim, and all the ordinary answers are question-begging.

How do we know that Bob’s recollection of the actions of Nestor (or Thersites) is

impossible rather than merely non-actual? How can it be ruled out that it is possible for

Bob to recall the actions of Nestor, although in fact he does not? Well, we might reply,

that would be a past life, and talk of recalling past lives is nonsense. Or, more simply:

Nestor is somebody else. As should be apparent, these answers only work if we have

50

Locke (2008), 43-44.

66

already assumed that Nestor and Bob are two distinct people, which is precisely what

Locke is arguing for in order to justify his conclusion that an immaterial soul can be

shared by different persons. To show that Bob could not possibly recall being Nestor,

Locke needs to identify something that divides Nestor from Bob which does not divide

Bob from events that happened to his actual current body but which Bob does not happen

to recall. But all the criteria we would normally think separate Bob and Nestor, but not

Bob and Bob’s forgotten past, rest on the assumption that Bob and Nestor are distinct

people. The facts about what Bob actually remembers successfully distinguish Bob from

Nestor, but also separate Bob from Bob’s sleeping self, and Bob’s forgotten past.

So, in short, to ensure that our sleeping selves and waking selves are one, that

events which have slipped our minds are still parts of our lives, Locke might allow that

identity may be a matter of where the consciousness could extend to, rather than where it

does extend to. But the only way to ground a claim about where consciousness could

extend but does not is question-begging. The Lockean seems to be reduced to claiming

that whatever separates Nestor from Bob, separates Nestor from Bob. This trivially true

claim is unhelpful in explaining how forgotten events from our own lives can be

considered to be from our own lives. As such, it seems that Locke’s approach does not

have an unproblematic way to avoid the conclusion that the sleeping self and the waking

self are one, or that an action one takes but later forgets is still an action taken by oneself

and not some other person in the same body.

Without a way to avoid that conclusion, it is readily apparent that Locke’s account

clashes with our ordinary beliefs about identity of persons. Tell an ordinary person that

67

she shares her body with another person who is only present when she sleeps, and she is

likely to assume that you are either joking or delusional. The claim sounds like an

uninspired science-fiction or horror scenario; it is not something that fits with our

ordinary beliefs about ourselves and our bodies at all. We simply do not believe that we

go out of existence when we enter dreamless phases of the sleep cycle and return when

we wake, leaving our bodies in the custody of some other person in the meantime.

Locke’s account also faces difficulty for claiming that it is truly identity that we

are concerned with in the matter of personal identity, since numerical identity is transitive

by definition but continuity of consciousness is not. Suppose that now, as I write my

dissertation, I can clearly recall my tenth birthday party. By Locke’s account, this means

that me-now and me-at-ten are identical; we are the same person, because I now bear the

memories of me at ten. But suppose also that, twenty or thirty years from now, I can

recall working on my dissertation but cannot recall my tenth birthday party. Because me-

in-twenty-years recalls writing my dissertation, by Locke’s account me-now and me-in-

twenty-years are identical. So because I now recall my tenth birthday, and in twenty

years will recall working on my dissertation, me-now is identical to both me-at-ten and

me-in-twenty-years. But I have stipulated that me-in-twenty-years does not recall my

tenth birthday party. So with continuity of memory as the criterion of personal identity,

me-in-twenty-years is not identical to me-at-ten, but both me-in-twenty-years and me-at-

ten are identical to me-now. In other words, Locke’s account of personal identity

depends upon a relation which is not transitive, but numerical identity is transitive.

68

Thus, this simplest possible version of the psychological continuity view,

according to which consciousness, remembering past actions, makes for continuity of

persons, leads to conclusions which are not compatible with our ordinary beliefs about

ourselves and faces metaphysical difficulties as well. How will a more sophisticated

view which calls for psychological continuity alone fare?

2.2 Parfit’s Psychological Continuity-based View

Derek Parfit argues that, regardless of whether it corresponds with strict

numerical identity or not, the feature we ought to care about when it comes to the

continuity of persons is psychological continuity. Psychological continuity, which should

be understood as a matter of degree, makes for survival, which he argues is what we

really care about, rather than strict identity. Parfit’s view thus differs from Locke’s in

that Locke seems to claim that psychological continuity – the extension of consciousness,

in Locke’s terms – makes for personal identity, in the full sense of the word ‘identity’,

while Parfit’s claim is that strict identity may not correspond with psychological

continuity, and that where it does not, identity is not the relation which matters.

Parfit defines psychological continuity as “the holding of overlapping chains of

strong [psychological] connectedness,” with psychological connectedness defined as “the

holding of particular direct psychological connections.”51

The direct psychological

connections associated with psychological connectedness include memory connections

like Locke prioritizes, but are not limited to memory: continuing to have a belief, desire,

51

Parfit (1986), 206.

69

intention, or any other psychological feature also is a psychological connection.52

Strong

psychological connectedness consists in a high number of individual psychological

connections, and should be understood as a matter of degree. The existence of a small

number of psychological connections is not sufficient for our survival – comparatively

small numbers of psychological connections also exist between people (having the same

belief or desire as someone else might be a case, for instance). A high level of

psychological continuity – consisting in a great number of particular direct psychological

connections in the form of memories, beliefs, desires, intentions and so on – is what

makes for our survival.

By defining psychological continuity in this way, Parfit provides a way to avoid

the transitivity issue associated with Locke’s account. Locke’s account calls for identity

through connectedness, and runs into problems because connectedness is not transitive.

Psychological continuity, defined in Parfit’s way, calls for overlapping chains of

connectedness. This means that, because the chain of psychological connectedness that

links me-now to me-at-ten overlaps with the chain that links me-now to me-in-twenty-

years, me-at-ten and me-in-twenty-years are psychologically continuous in spite of

lacking some or all of the direct psychological connections that tie me-now to either one.

In short, psychological continuity is transitive where psychological connectedness is not.

However, Parfit does not use this difference between his account and Locke’s to

argue that psychological continuity, and not direct psychological connectedness, make for

identity. Parfit rejects the assumption that strict identity is what matters to us. His claim

52

Parfit (1986), 205.

70

is that psychological continuity, with any kind of cause, is what matters when it comes to

what we care about for our survival.53

Parfit illustrates the difference between his claim and the claim that strict

numerical identity is what matters by describing a case in which the individual (call her

Claire) faces one of two outcomes. One possibility is that she will live on for many

years. The other possible outcome is that Claire’s death is imminent. On the assumption

that her life is and will continue to be worth living, it seems obvious that the former

option is better for Claire. Ordinarily, we think that what separates these cases is

whether, in the intervening years, there is someone living who is Claire – in other words,

whether there is some living person who is identical to Claire. Parfit’s claim is that it

does not matter whether there is some living person identical to Claire during the

intervening years. What matters is that there is some living person who is

psychologically connected and/or continuous with Claire, regardless of how that person

came to stand in that psychological relationship to Claire. A person who is

psychologically continuous with Claire allows Claire to survive, Parfit claims, even if

that person is not identical to Claire. If Claire will die imminently, but a person who is

psychologically continuous with her will live on for many years, this is about as good for

Claire as surviving in the ordinary way would be.54

53

Parfit (1986), 215.

54 Parfit (1986), 215.

71

Parfit acknowledges that this view is not intuitive; he refers to the view that

‘personal identity is what matters,’ the view he is arguing against, as “the natural view.”55

In ordinary circumstances, psychological continuity and personal identity coincide, so in

actual practice, his view and the view that personal identity is what matters will seldom

diverge. However, his claim is that acceptance of one over the other will have

considerable implications, which may even call for revisions in what behavior is

considered rational or moral.56

Given this, it probably seems obvious that Parfit’s view will not make a good

answer to the question I have posed. Parfit’s aim with his account is not to develop a

metaphysically-coherent view which fits with our actual beliefs and practices about the

continuity of persons, but to offer an account which prioritizes metaphysical coherence

over fit with our beliefs. The ‘right’ view, for Parfit’s purposes, may be one that differs

wildly from our ordinary beliefs. Thus, his goal is radically different from mine here.

However, it is worth considering his arguments for his view. In rejecting the role of strict

identity on the grounds that it is not what matters, Parfit prioritizes mattering; for this

reasons, his conclusions may be relevant to the question I gave even though his intent is

to answer a different question. ‘What matters’ certainly sounds like a relevant

consideration for my purposes: what matters to us when it comes to our continuity has

great potential to be informative about how we regard ourselves when it comes to our

continuity. His arguments for why psychological continuity matters where strict identity

55

Parfit (1986), 215.

56 Parfit (1986), 215.

72

does not may result in a view which is plausible as an answer to my question after all,

even if it sounds false on the surface.

Parfit’s series of teleportation cases57

serves as a fleshed-out version of his two-

outcomes case. Suppose that Claire steps into a teleporter on earth, pushes a button to

activate the machine, and steps out of a teleporter on Mars. In the first teleportation case,

this is achieved by the teleporter on earth scanning Claire’s body, recording the exact

state of every particle composing her, and transmitting the information to the receiving

teleporter on Mars. The teleporter on earth now destroys the original. At the same

moment, the receiving teleporter on Mars recreates Claire from local material, perfectly

matching the information about her state recorded an instant ago on earth. (Call the

resulting woman ClaireM.) ClaireM’s experience of the transition is seamless – she will

recall entering the teleporter on earth and emerging, whole and healthy on Mars a

moment later, ready to pursue whatever business she has there. This case is generally

considered to be plausible – such technology is a staple of science fiction, for instance;

the idea that we could someday travel in this way is common and does not test the limits

of credulity.

In the second case, rather than destroying the body which enters the teleporter on

earth, the transmitting teleporter merely scans the body and transmits the data to the

receiving teleporter on Mars, which, as in the first case, recreates the body on Mars using

local material. This case is identical to the first case except that the teleporter on earth

does not destroy anything. This case will result in two living humans, perfect duplicates

57

Parfit (1986), 199-201.

73

of one another: one who entered a teleporter on earth, was scanned, and emerged

unscathed (ClaireE), and another who was assembled on Mars out of local matter

(ClaireM). They are physically and psychologically identical, down to the last electron:

they have the same personality, the same desires and fears, and the same memories, up to

and including entering the teleporter on earth. They will begin to diverge once they step

out of their respective teleporters, since one is on earth and the other on Mars, but prior to

that moment, they are identical, and both are psychologically continuous with Claire as

she was scanned in the teleporter on earth.

As noted, the first case is considered plausible, a description of a novel way to

travel. It is not considered a futuristic new way to die, but a way to move from one point

to another without having to bother with the space in between the two. If this

interpretation of the first case is correct, and teleportation is a way to travel and not a way

to die, then the individual who enters the teleporter survives the teleportation: Claire is

alive after the teleportation. Since the human body that entered the teleporter on earth

was destroyed, the human body that was created from local matter on Mars is the only

candidate for being the person who survived the teleportation. If Claire survives the

teleportation described in the first case, Claire survives as ClaireM. Thus, if teleportation

is transportation and not a way to die, if teleportation is something we can survive, then

ClaireM, the woman who steps out of the teleporter on Mars, has the sort of continuity

required for continued existence of a person with Claire, the person who stepped into the

teleporter on earth.

74

If all this is true of the first case, then we ought to think that it is also true of the

second. The second case, recall, differs from the first only in that the human in the

transmitting teleporter on earth is not destroyed. Everything else about the second case is

the same as the first case. What does this demonstrate? It seems to show that in the

second case, Claire survives in two humans after teleporting: ClaireE, who emerges

unscathed from the teleporter on earth, and ClaireM, who emerges from the teleporter on

Mars, a perfect duplicate having been assembled from local matter.

Parfit acknowledges that ordinarily, we might be inclined to say that only ClaireE

is the same person who entered the teleporter on earth, and that ClaireM is not Claire:

after all, all this person did was step into a machine and get scanned. This does not seem

to be the sort of radical change that could result in a branched existence for Claire the

way that, say, cutting her brain in two might. People are scanned by machines for

security or medicine every day, and we do not even momentarily think that they might be

branching into two people because of it.

However, if we say that in the first case, Claire survives as the ClaireM, which is

plausible, then we ought also to say that in the second case, Claire survives as ClaireM.

The only difference between the cases is what happens to the body that remains on earth,

whether it is destroyed or not. The destruction or lack thereof of a separate human body

does not seem to be the right sort of event to impact the identity of the occupant of

another body. Thus, if Claire survives as ClaireM in the first case, we ought to say that

she survives as ClaireM in the second case, too, because what happens to ClaireE doesn’t

seem to be the kind of thing that could affect who ClaireM is. But we’ve also said that

75

ClaireE, simply having been scanned, must be the person who stepped into the teleporter

on earth. So it appears that in the second case, Claire survives as two people following

her scan in the teleporter: ClaireE, who emerges unchanged from the teleporter on earth,

and ClaireM, who emerges on Mars having been assembled from local matter. This result

is unintuitive; we would ordinarily think that only the person who steps out of the

teleporter on earth, having simply been scanned after stepping into the teleporter, is the

same person who stepped in; in other words, ClaireE seems to have a better claim on

being Claire than ClaireM does. However, acceptance of the first case, simple

teleportation, supports the conclusion that ClaireM is the same person as Claire, too.

Finally, Parfit’s third case is a variant on the second. In this case, Claire steps

into the teleporter on earth and is scanned. The data is sent to Mars, and, as in the

previous cases, a perfect duplicate, ClaireM, is formed on Mars out of local matter.

However, this time, the woman who steps out of the transmitting teleporter on earth,

ClaireE, does not emerge from the scan unscathed. The scan has damaged her heart, and

she only has a short time left to live. Parfit’s claim is that this is not really a problem for

ClaireE. Acceptance of the first case shows that a human can continue to exist through a

perfect duplicate made of entirely different matter; the first case was understood as a case

of Claire travelling to Mars, not a case of Claire dying. This third case, where the

original Claire’s life overlaps briefly with the duplicate’s, is not relevantly different from

the first case. If a duplicate is good enough when the original is destroyed

simultaneously with the creation of the duplicate, then a duplicate ought to be good

enough when the original dies shortly after the creation of the duplicate. Thus, Parfit

76

concludes that for ClaireE, surviving through a duplicate, identical physically and

psychologically, is not much worse than surviving in the ordinary way, with the same

body she has had all along. Though it is likely, Parfit admits, that ClaireE will feel

distress at learning of her imminent death, he claims that this response is not rational and

does not reflect the reality of her situation, that although her body will die, that which

matters about her, her psychology, will be carried on in a duplicate body at another

location. For Claire, case one and case three should be understood as just about the same

as one another; the brief period of overlap in the third case, absent in the first, is not the

right sort of thing to make the third case a tragedy for her while the first case is not. The

small differences between ClaireE and ClaireM which result from the short period in

which the two coexist are not sufficient to constitute a break in continuity. ClaireE thus

survives as ClaireM in this case, just as Claire survives as ClaireM in the first case.

Thus far, Parfit’s conclusions are not so radically opposed to our ordinary

thinking that this view could not serve as an answer to the question I address. Although

our intuitions will tell us that, in a case like the second case, only ClaireE is Claire, and

ClaireM is a mere duplicate, not really Claire, acceptance of the first case does very

clearly lead to the conclusion that ClaireM is Claire too. One need not be a philosopher to

see this. If ClaireM is Claire in the first case, then ClaireM must be Claire in the second

case, too: the fact that a human body was not destroyed does not seem to be the right sort

of thing to affect which person occupies an entirely separate human body (that is, it is not

the right sort of thing to affect whether ClaireM is Claire or not).

77

Our ordinary intuitions on the third case, too, differ from what Parfit says: we

certainly are not inclined to think that our own deaths are not particularly bad things!

Here again, though, it is easy to see, without any dubious philosophical twists and turns,

that if we accept the first case and the second, we ought also to accept Parfit’s conclusion

for the third. The fact that there is a short period of time where two women bear Claire’s

psychology does not seem to be the sort of thing that could impact whether ClaireM is

Claire or not. Denying this would require acceptance of the conclusion that the

psychological states of a person, remotely located, doing nothing to impact my body,

could cause me to cease to be me, since that is how it would be for ClaireM if the

existence of another person, ClaireE, could determine whether ClaireM is Claire or not. It

seems obvious that we should reject the claim that the psychological states of another

person, not interacting with me in any way, could cause me to cease to be me. In light of

this, it certainly seems like Parfit’s conclusion, though counterintuitive on the surface,

follows in an obvious way from acceptance of the first case and principles that we should

be loath to reject. In other words, though Parfit’s conclusion differs from our first-take

intuitions, the reasoning employed to arrive at his conclusion is clear-cut and reasonable,

and does not require the acceptance of any particularly unintuitive claims: it is a

conclusion that a simple, plausible line of reasoning makes acceptable, in spite of not

fitting our prima facie intuitions.

However, Parfit’s account goes further than this, and arrives at conclusions which

are sharply opposed to our ordinary intuitions about our own existence and survival, so

much so that his account cannot be considered a good fit for our actual beliefs and

78

practices. Parfit’s claim that psychological continuity is all that matters goes further than

cases like the teleportation cases. His claim is not only that psychological continuity, and

not strict identity, is what matters, but that psychological continuity with any cause

whatsoever is what matters. This detail is an important one for my purposes, as it takes

Parfit’s view from one that is counterintuitive at first blush, but which follows naturally

from what we do believe and doesn’t demand us to accept anything radically opposed to

our ordinary beliefs, to one that makes behavior that is clearly irrational by any ordinary

concept of rationality perfectly reasonable.

Parfit’s claim about our survival is that we survive where our psychology occurs.

This conclusion seems quite plausible when it is argued for by way of the series of

teleportation cases. By beginning with a familiar fictional case that we are likely to

accept, Parfit shows that many of the things we think might impact survival (not being

unique, and strict identity) seem unimportant. We can accept the idea that Claire can

survive as ClaireM even though ClaireM’s existence overlaps briefly with ClaireE’s

because we accept that in the ordinary teleportation case, Claire survives as ClaireM, and

the conclusion that the same occurs when there is overlap follows if we accept a very

plausible principle. The familiarity through fiction of the ordinary teleportation case,

combined with the plausible claim that whatever you do to someone else, far away, not

interacting with me, cannot affect who I am, leads to the conclusion that Claire survives

as ClaireM even when the original Claire dies sometime after the creation of ClaireM.

Parfit’s assertion that our psychology is what matters is not limited to familiar,

“comfortable” cases like teleportation, however. His assertion is that psychological

79

continuity, with any cause, is what matters for our survival.58

The teleportation cases,

and our willingness to accept them, show that teleportation is one cause we can accept as

making for survival. What makes Parfit’s claim so counterintuitive is his stipulation that

any cause whatsoever of psychological continuity will do.

Claiming that something like teleportation is a means of survival does not stretch

our beliefs too far for acceptance, but the claim that any source of psychological

continuity, whether it is a reliable method or pure chance, flies in the face of what we

believe about ourselves and our own survival.

To draw out the problem, it is helpful to consider a pair of cases. For the first, I

shall return to Claire, our teleportation-user: she enters a teleporter on earth, is scanned,

and a perfect duplicate of her body, exact to the last electron, is created on Mars from

local material. This case is identical to the one before: per Parfit’s view, the duplicate

created on Mars, ClaireM, is someone through whom Claire survives, and surviving

through ClaireM is just about as good as surviving in the ordinary way.

Contrast the case of Claire’s teleportation with this one. Dan is going about his

life in a perfectly ordinary way. On his way to work one day, he is hit by a bus and dies.

However, as it happens, just minutes before Dan’s accident, someone else, across the

globe, suffered an injury too: Eric, a complete stranger to Dan, suffered a head injury.

Bizarrely enough, this head injury caused Eric to spontaneously acquire the memories,

beliefs, desires, personality and so forth of Dan. This was pure chance – it was not a

result of the meddling of a nefarious neuroscientist, or something supernatural like Dan’s

58

Parfit (1986), 215.

80

‘soul’ taking residence in another body, for instance, just a highly improbable

neurological rewiring due to a head injury.59

According to Parfit’s view, Dan’s situation is the same as Claire’s. Claire

survives through ClaireM, and following the teleportation, can go about her life as usual –

surviving through ClaireM is just as good as surviving without teleportation would have

been. This conclusion is not too striking. As noted previously, travelling via

teleportation is a familiar notion in science fiction; we are not surprised or confused when

characters in a work of science fiction travel in this fashion. However, Dan’s case is

much less familiar. Dan’s consciousness, with all its relevant features – memories,

beliefs, desires, personality and so on – shows up in Eric’s head. Dan happens to die

moments later (or even concurrently, to avoid concerns about branching). Per Parfit’s

view, Dan survives through Eric, just as Claire survives through ClaireM.

This conclusion, unlike the conclusion about Claire’s teleportation, is quite

jarring. If Dan were told of his impending death, would he be comforted by the

knowledge that somewhere out there, another man bears his psychology? Will Dan’s

family not grieve if they are told that, although Dan is dead, someone else out there

thinks just like Dan? Should Dan, knowing that there is a perfect psychological duplicate

59

Stipulating these conditions – the fact that Eric’s acquisition of Dan’s psychology is a matter of pure

chance – is not unfairly stacking the deck against Parfit, since Parfit is clear that per his view, any cause of

psychological continuity is sufficient for survival. A truly coincidental, meaningless cause like a bizarre

head injury counts.

81

of him out there, stop looking both ways before crossing the street? The obvious answer

seems to be no, but by Parfit’s account, the answers should be yes.

The claim that Claire survives as ClaireM in a case where ClaireE and ClaireM

coexist, as in Parfit’s second and third cases, was somewhat counterintuitive as well.

However, as discussed earlier, this conclusion follows simply and directly from

acceptance of Parfit’s first case, where Claire survives as ClaireM only. Dan and Eric’s

case can be set up to be parallel to Parfit’s first case, for simplicity’s sake; say that Eric’s

head injury, and spontaneous acquisition of Dan’s psychology, occurs at the very same

moment that Dan dies, thousands of miles away. By stipulating that their lives do not

overlap at all, this case is made analogous to Parfit’s first teleportation case, which was

easy to accept. However, eliminating the slight overlap between Dan’s life and the time

when Eric has Dan’s psychology does not make the conclusion that Dan survives through

Eric any more believable. Dan should still be extremely concerned by the prospect of his

imminent death. The knowledge that someone, somewhere out there, will have a

psychology very like his own will not allay his concern about his imminent death, nor

should it. (Parfit would likely agree that Dan will be concerned about his imminent

death, but would claim that Dan ought not to be concerned by it.)

What separates the case of Claire from the case of Dan? Both ClaireM and Eric

are composed of entirely different matter from the individuals who survive through them.

Physical continuity does not explain why Claire’s case is believable while Dan’s case is

not. The relevant difference seems to be the causal relationship that exists between

Claire and ClaireM which is absent between Dan and Eric. Although Claire shares no

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matter with ClaireM, and ClaireM is not the most natural successor for Claire in all cases

(because in cases where ClaireE exists, ClaireE, and not ClaireM, is the most natural single

choice of who Claire survives as), ClaireM has a causal relationship with Claire that Eric

does not have with Dan. The reason why ClaireM’s psychology is the way it is (namely,

identical to Claire’s) is because that is how Claire’s psychology is. If Claire’s

psychology had been different, then ClaireM’s psychology would have been different too

– however Claire’s psychology is, that is how ClaireM’s psychology will be too.

ClaireM’s psychology is defined by Claire’s psychology, because the facts of Claire’s

psychology dictated the facts of ClaireM’s psychology. The same is not true of Dan and

Eric. As stipulated in the details of the case, there is no underlying reason for Eric’s

psychology to suddenly be identical to Dan’s at the time of Dan’s death. It is purely a

bizarre coincidence. The causal connection between Claire’s psychology and ClaireM’s

psychology is not present between Dan’s psychology and Eric’s psychology.

Thus, there is a plausibly-relevant difference between the case of Claire’s

teleportation and Dan’s death. Acceptance of Parfit’s three teleportation cases, then, does

not require us to accept his further conclusion, that any cause of a high degree of

psychological continuity, even a cause based only on chance rather than a causal

connection between the relevant humans, is sufficient for survival.

For this reason, it is no contradiction to reject Parfit’s view as an answer to the

question I have posed based on its results for Dan and Eric’s case, even though its results

for Claire’s cause are potentially plausible in spite of their counterintuitive elements. Full

acceptance of Parfit’s view requires us to accept that our own deaths might be of no

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particular importance to us, so long as there is someone else out there quite similar to

ourselves. This is clearly contrary to our ordinary beliefs about ourselves. If a complete

stranger happens to be very like me psychologically – even identical to me

psychologically – that fact will not make me take my own potential death any less

seriously. Knowing that someone who will live on is very like me will not make me

indifferent to my own death. Parfit’s claim is that it should, but accepting such a

conclusion would require radically altering one’s views about the continuity of persons

and the self. As such, Parfit’s view cannot be considered a good answer to my question.

It calls for results so far afield from our ordinary pre-philosophical beliefs about the

subject that the discrepancies cannot be explained away.

Thus, neither Locke’s simple memory-based psychological continuity approach

nor Parfit’s rejection of personal identity as the criterion for continuity in favor of

psychological continuity is a good fit for our existing ordinary beliefs and practices about

the continuity of persons. With these two serving as representatives of the spectrum of

views that call for psychological continuity only, it looks as though psychological

continuity in general will not be sufficient for continuity of persons. However, neither

can the significance of psychological continuity be dismissed entirely – these views

accommodate many of the beliefs we have about ourselves and our own continued

existence.

3 Physical Continuity Views

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With views that call for psychological continuity alone as the criterion for

continuity of persons apparently unable to fit with our existing beliefs and practices

concerning personal identity, I now move to consider views which reject a role for

psychological continuity in the continuity of persons: views which call for physical

continuity as a necessary condition for the continuity of persons and do not require

psychological continuity.

I first consider a simple version of a physical continuity account, which holds that

people are their bodies, regardless of whether the brain (or any other organ) is

functioning typically or not. As a more sophisticated variant on the physical continuity

view, I will consider the biological approach, also called animalism: according to this

view, the continuity of persons should be understood in much the same way we would

understand the continuity of any other animal, without prioritizing the mental features of

humans. Animals are best understood as living organisms; as such, the continuity of a

given animal amounts to its continued existence as a living organism. Thus, this view

holds that the continuity of persons should be understood in terms of continued existence

as a living organism.

3.1 People as Their Bodies

The simplest possible view which calls for physical continuity and ignores

psychological continuity can be expressed by the claim “people are their bodies.”

Proponents of this sort of view argue that it is an intuitive and natural way to understand

ourselves. Judith Jarvis Thomson, for instance, characterizes the view that people simply

85

are their bodies, regardless of the psychological status of that body, as “the simplest view

of what people are” and something that everyone accepts at true at least some of the

time.60

These claims about the simplicity and intuitive appeal of views which prioritize

physical continuity and leave aside psychological continuity are obviously relevant to the

question I address here: intuitiveness and the like are qualities which the view that best

fits our actual beliefs and practices ought to have.

What does this simple version of a physical continuity view actually say, then?

Its slogan-style name conveys most of the information: people are their bodies. In other

words, people do not merely have bodies; people are bodies. People are their bodies

even when those bodies are not conscious (as in sleep) or have been damaged such that

they will never again be conscious (as with comas or persistent vegetative states

following serious brain damage). What makes for the continuity of people, per this

account, is having the same body. Some person x is continuous with (the same person as)

some person y if and only if x’s body is y’s body.61

This sort of view differs sharply

from psychological continuity views in particular, and the transplant intuition itself, in

that it does not prioritize any particular part of the body. The brain is given no special

role; a brain transplant is understood as no more significant with regard to personal

identity than a liver transplant.62

60

Thomson (2008), 155.

61 Thomson (2008), 156-157.

62 Thomson (2008), 158.

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According to this sort of view, then, the transplant of a normally-functioning brain

from one body to another is no more meaningful than the transplant of a liver or kidney

from one body to another. If Anne donates a kidney to Beth, then Beth comes to have a

part of Anne’s body in her body, but common sense beliefs tell us that this does not have

any impact on the identity of either Anne or Beth. Anne is Anne, less a kidney, and Beth

is Beth, although her body now includes a piece of Anne’s body. The simple physical

continuity view interprets brain transplants in the same way. Suppose that the brain has

been removed from Beth’s body. Anne’s brain is transplanted into Beth’s body, leaving

Anne’s body brainless, shortly to die without a brainstem to manage life-sustaining

functions. The simple physical view tells us that the surviving person is Beth, not Anne.

Anne dies when her body dies, while Beth lives on, having simply had another person’s

organ transplanted into her, just as in the case of a kidney transplant. In virtue of having

Anne’s brain, Beth will believe that she is Anne, recall events which happened to Anne

from a first-person perspective and so on, but she will not be Anne. She will be Beth,

erroneously believing that she is Anne.

How well does this simple physical continuity view fit with our actual beliefs and

practices? Thomson claims that “we all, at least at times, feel inclined to think that we

are not merely embodied, but that we just, all simply, are our bodies,” and that one’s

hand, for instance, is literally a part of oneself, not merely a part of something to which

one is connected.63

If this claim is true, it gives reason to think that the simple physical

view is a good fit for our actual beliefs and practices concerning our own continuity,

63

Thomson (2008), 155.

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because it bears on what we are. However, even if Thomson’s claims about what seems

natural to believe are granted, other aspects of the simple physical view are too

counterintuitive. The advantage the simple physical view may gain from allowing that

our body parts are literally parts of us is countered by its poor fit with other strongly-held

intuitions.

Thomson does not provide much support for her claims that we think of ourselves

as identical to our bodies and that our body parts are literally parts of us, perhaps taking

them as obvious. Even if we do not challenge this point and grant these claims to

Thomson, they are not sufficient to show that the simple physical view is a good fit for

our actual beliefs and practices about our continuity. Even if we grant that there is a pull

to think of ourselves as identical to our bodies, to think of our hands as literal parts of

ourselves, the failure to prioritize the brain over any other body part makes this version of

the physical view a poor fit for actual beliefs and practices concerning our continuity.

The simple physical view holds that the brain is no more important for continuity than the

liver or any other organ. It says that I could remain me were my brain to be removed and

replaced with another, just as I could if my liver were removed and replaced with

another. Obviously, this contradicts the transplant intuition, which holds that if my brain

is removed and destroyed, I will cease to exist, regardless of whether some other brain

gets put into my body.

Thus, at best the simple physical view has some intuitive appeal on the basis of its

ability to say that we are our bodies, that our body parts are literally parts of ourselves,

which certainly seems like something we ordinarily think. But it also conflicts strongly

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with our beliefs by discounting the significance of the brain. The belief that our brains

are different, special with regard to making us who we are, seems to be quite common,

confirmed by empirical data from experimental philosophy64

, but also by dozens of

examples from sources having nothing to do with philosophy, ranging from science

fiction to children’s cartoons65

. Thus, a view which discounts the special significance of

the brain, which holds that transplanting one’s brain into another person’s body and

destroying one’s original body is death, simply gets it wrong per our ordinary beliefs

about ourselves and our bodies. Ask an ordinary person, a non-philosopher, if she would

prefer to have her brain put in another body and then have her body destroyed, or have

her body destroyed with her brain in it, and the choice will be obvious. Saving the brain

has value in a way that saving another organ does not. (One might think that there is

value of some kind in having one’s other organ’s placed in another body, but the value of

this is in the moral good of helping the recipient, not in preserving one’s own existence.)

It would be difficult to justify an assertion about which belief is more essential,

about whether the belief that my hands are a part of me is more powerful than the

transplant intuition. Rather than attempt to argue that one is more strongly-held than the

other, I will leave it that the simple physical view has some possible points in its favor,

64

Nichols and Bruno (2010), as discussed in the first chapter.

65 Instances of individuals surviving as brains separated from their bodies occur in the original Star Trek

series, Futurama, Mystery Science Theater 3000, Doctor Who, French film The City of Lost Children,

science fiction stories and novels including works by H.P. Lovecraft, Roald Dahl, and others. An

extensive list of fictional instances of brains kept functioning separated from their bodies is available at

TVTropes.org (TVTropes.org, 2013).

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for accommodating the seemingly ordinary belief that our body parts are parts of us, but

that it also has some significant points against it in terms of fit with our beliefs and

intuitions about our own continuity for contracting the transplant intuition. In spite of its

potential merits for having some points of fit, the simple physical view is not a very good

fit for our beliefs and intuitions about our own continued existence.

3.2 Animalism

Animalism, in the personal identity debate, can be roughly characterized as the

belief that people are animals, and the continuity conditions of people are the continuity

conditions of animals. Animalism prioritizes physical continuity and discounts

psychological continuity: so long as a given entity remains an animal, psychological

changes are not relevant to its continuity. This view differs from Thomson’s simple

physical-continuity based view in that proponents of animalism generally do not claim

that the continuity of animals is dependent upon the physical continuity of the entire

animal; animalism focuses instead on the continuity of life-maintaining function.

Because the brain, specifically the brainstem, fulfills this role, animalism prioritizes the

brain over other parts of the body, where Thomson’s account rejects this special role for

the brain in the continuity of persons.

Olson characterizes animalism/the Biological Approach as “the view that you and

I are human animals, and that no sort of psychological continuity is either necessary or

sufficient for a human animal to persist through time.”66

This claim should be

66

Olson (1997), 124.

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distinguished from the claim that all persons are human animals with no sort of

psychological continuity necessary or sufficient for their persistence through time. This

latter claim would eliminate the possibility of non-human persons, such as gods and

angels, artificial intelligences, and more. It is not a part of the animalist’s claim that such

things are impossible; rather, the assertion is simply that we are not such things, but are

human animals. There are some difficulties associated with this formulation of

animalism. Granting the possibility of persons to whom animalism does not apply, how

is the animalist to articulate which entities his view does apply to? Animalism becomes

trivial if it is merely the assertion that all human people are human animals, because that

formulation leaves open the possibility that there are no human animals, that Olson and

Parfit and I and everyone else are all something else, such as Cartesian egos.67

Olson’s initial statement of animalism suggests one possible way to avoid this

problem; he states that you and I are human animals. However, as Jens Johansson notes,

this way of avoiding the problem with articulating animalism results in its own problems.

It does not fully express the claim of animalism, since the animalist’s claim is not just

about himself and whoever might read his work on animalism – the animalist’s claim,

properly expressed, applies to far more entities that merely ‘you and I.’ It does not

express a claim which all animalists accept: as Johansson puts it, “I would have thought

that Aristotle was an animalist; but since he never heard of you and me, he did not accept

[that you and I are identical with animals].”68

Even an animalist who is acquainted with

67

Olson (1997), 125.

68 Johansson (2007), 198-199.

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you may be disinclined to assert “you and I are identical with animals” if they have

somehow come to mistakenly believe that you are not a human person but something

else, like an artificial intelligence or an alien.69

In short, the use of ‘you and I’ in the

formulation narrows the definition of animalism too far.

Johansson concludes that the most plausible accounts of animalism, which he

identifies Olson’s as, seem to assert that “all typical human persons are identical with

animals.”70

With the basic claim of animalism thus defined, we can move on to what an

animalist account has to say about the persistence conditions of animals, including human

animals. Olson asks us to imagine the situation of Tim and Tom, two ordinary people.

Each man’s right arm is severed, and Tim’s right arm is attached to Tom’s body where

Tom’s right arm used to be. The arm is fully integrated into Tom’s body – the tissue will

not decay, there will not be an adverse immune response, etc. Olson asserts that it is

obvious that the resulting organism, composed of Tim’s right arm and everything of Tom

but his right arm is Tom, and not Tim.71

I agree that this is in line with our ordinary

beliefs about such a procedure.

One ordinary way we might explain this result is the fact that most of the resulting

organism’s matter comes from Tom, not Tim, and is put together just as it was before any

arm-severing occurred. The resulting organism is a lot more like Tom-before than it is

like Tim-before, because most of its matter comes from Tom. Comparatively little comes

69

Johansson (2007), 199.

70 Johansson (2007), 205.

71 Olson (1997), 131.

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from Tim. However, contrasting the case of arm transplant with the case of head

transplant reveals the deficiency of this explanation. If we remove Tim and Tom’s heads,

and put Tim’s head on Tom’s body, the proportionate amounts of matter that come from

each body is similar to the arm case: most of the resulting organism came from Tom’s

body, not Tim’s. The head is much smaller than all-the-body-but-the-head. But the head

is unlike an arm in that the head is responsible for life-sustaining function. A headless

human body is not a living organism, whereas a human body missing its right arm can

remain a living organism. By contrast, a severed human head may be able to survive as a

living organism without a body. The head will require extensive life-support, but can

survive with it. A body without a head can perhaps be stimulated into certain basic

functions (like “breathing” via a respirator) but these functions are maintained only by

external mechanisms, whereas a severed head, given proper inputs, could maintain its

own life.72

Effectively, a headless body will stop life functions unless they are forced on

it externally, whereas a body-less head will maintain life functions as long as it has the

means to do so. Olson’s claim, then, is that “[p]art of what makes something a living

organism… is its capacity to coordinate and regulate its metabolic and other vital

functions.”73

Combining this with the claim that animals persist as living organisms, and the

assertion that we are human animals, the result is the claim that the capacity to coordinate

and regulate our metabolic and other vital functions is necessary for our persistence.

72

Olson (1997), 131-133.

73 Olson (1997), 133.

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Here, the difference between this view and Thomson’s simple physical view becomes

apparent: per this formulation of animalism, an animal ceases to exist upon death,

necessarily so. Olson notes that this is not so absurd as one might think: “a ghost town is

not a town, a dry lake is not a lake, a tin soldier is not a soldier, and a dead person is not a

person.”74

Thus, animalism’s claim about the persistence conditions of a human animal

can be expressed as the claim that “[f]or any organism x and any y, x = y if and only if x’s

life is y’s life,”75

with ‘life’ understood as “a special kind of event, roughly the sum of the

metabolic activities the organism’s parts are caught up in.”76

How does animalism fare in terms of fit with our beliefs and practices concerning

our own continuity? Although it is able to easily accommodate certain ordinary beliefs

where other accounts falter, animalism also has consequences which conflict significantly

with our beliefs and practices concerning our own survival.

Many of the arguments in favor of animalism emphasize its ability to handle

seeming truths that other accounts are unable to accommodate. One immediate

advantage of animalism is its ability to accommodate the claim that each human was once

a fetus. Fetuses do not possess the psychological characteristics necessary for

personhood at the start of their existence; thus, if an individual is understood as a

psychological entity, it is false to say that the individual was once a fetus, because a fetus

lacks psychological features. An early fetus simply isn’t the sort of thing that can be a

74

Olson (1997), 135-136.

75 Olson (1997), 138.

76 Olson (1997), 136. Life is defined similarly in van Inwagen (1990).

94

person, so if a given person is a psychological entity, she was never a fetus, because a

fetus cannot be a psychological entity.77

It seems obviously true that any one of us who

did not spring full-grown from the head of Zeus was once a fetus, so the ability of

animalism to accommodate this belief is a point in its favor when it comes to

accommodating our actual beliefs and practices. Animalism is able to accommodate the

claim that each human being was once a fetus, because although a fetus is not a person in

the philosophical sense, it is an animal life even prior to birth. Thus, it is true that I was

once a fetus so long as there is some fetus whose life is identical with my life. There is

such a fetus, and so animalism allows that I was once a fetus, thus successfully

accommodating this very reasonable belief while psychology-based views find difficulty

with it.

Like Thomson’s simpler physical continuity view, proponents of animalism also

argue that it is more natural than psychological continuity views. Eric Olson argues,

quite plausibly, that unless we regard ourselves as non-material, we must be human

animals: if we take ourselves to be material, what material being but a human animal

might we be? We ordinarily take ourselves to be members of Homo sapiens if we take

ourselves to be material beings at all.78

On the assumption that we are material beings,

animalism has a natural answer to the question of what we are; it is not clear that other

views have such a natural answer without committing to a non-material account of what

we are.

77

Olson (1997), 73-75.

78 Olson (1997), 95.

95

Thus, animalism accommodates two very ordinary beliefs we have about

ourselves: the belief that we were all once fetuses, and the belief that, if we are something

material, we are human animals (though ordinary people almost certainly do not

consciously accept this conditional, they are likely to agree with it if it is explained to

them).

However, animalism also departs with our ordinary beliefs in significant ways.

Animalists acknowledge this: Olson, for instance, explicitly acknowledges that

animalism may not reflect the things we actually care about. He notes that many of our

concerns when it comes to survival may be “based on practical concerns that may be

perfectly valid but that do not necessarily coincide with numerical identity.”79

Thus, it is

apparent that Olson’s focus, at least, is on numerical identity of human animals, even if it

turns out that numerical identity of human animals is not something that we ordinarily

care about.

Animalism does have an edge over the simple physical view with regard to the

transplant of brains. Per animalism, transplant of a whole brain does result in body-

swapping: if I remove the entirety of Frank’s brain and transplant it, connecting it

appropriately, to Greg’s body, Frank becomes the occupant of Greg’s body. Thus far,

this seems like good news for animalism, perhaps even a fit with the transplant intuition.

However, this is not the case. Animalism does prioritize the brain, and thus

accommodates our beliefs better than Thomson’s simple physical view, but on closer

examination, animalism conflicts with the transplant intuition after all. Olson’s

79

Olson (1997), 44.

96

animalism holds that the brainstem is essential to a person’s continued survival.80

As

discussed in the previous chapter, empirical evidence concerning the transplant intuition

reveals that the part of the brain relevant to our intuitions about brain transplant is the part

responsible for memory and other psychological features, the cerebrum. Further, it seems

easy to imagine that an artificial brainstem could replace an organism’s brainstem

without disrupting the continuity of that organism.

Olson argues that replacement of the brainstem does result in the death of the

organism, even though the organism appears to survive with the aid of an artificial

brainstem in the place of the original. His claim is that, however briefly, the organism

lost its capability to regulate its metabolism and that disruption ends the organism’s

existence. Olson attempts to ameliorate the oddness of this conclusion by noting that we

are aware that parts of an organism can continue to function after the death of the

organism – this is what makes organ transplant possible. The claim is that the organism,

although seeming to continue to function as normal, actually dies as soon as its brainstem

is removed and merely continues to function in the way that an organ can continue to

function for a limited amount of time after the body it is in has died. 81

Olson also considers a way that one might attempt to avoid this conclusion, but

argues that it, too, does not succeed at showing that the brainstem is inessential. To avoid

the momentary interruption of function that would result in the organism’s death, one

might swap out parts of the brainstem gradually so that the ability to regulate life-

80

Olson (1997), 140.

81 Olson (1997), 140-141.

97

sustaining function never stops even momentarily, but at the end there is a wholly

artificial brainstem. The result would seem to be a healthy human with an intact, fully

functional cerebrum which never experienced any interruption of its ability to maintain

life-functions that might be thought to constitute its death. Olson is quite clear that, in

spite of appearances, this resulting entity would not be the original human – in fact, they

would not be a human at all, because a human animal requires an organic brainstem per

Olson’s view. He admits that this result is surprising, but his answer to the charge is

unsatisfying: he states that it is merely a consequence of what seems, to him, to be the

best account of the identity of living organisms.82

Olson is correct that this conclusion smacks of the absurd; for his purposes, this

may not be fatal, but given that my aim is to identify a view that fits with our actual

beliefs and practices, it makes Olson’s animalism an untenable possibility. The idea that

a functional human being, with memories intact, continuing to operate in a typically

human way for years afterwards, ceases to exist by the replacement of a part of the brain

not associated with any higher function is sharply opposed to our beliefs about ourselves.

In cases where the brain stem and the cerebrum are separated, it is immediately obvious

that our intuitions regarding survival prioritize the cerebrum and not the brain stem. The

idea that we may be able to survive the death of our physical bodies by replacing the life-

sustaining parts is familiar: we can imagine life spent as a cerebrum-in-a-vat, the brain’s

basic functionality sustained by an artificial method. On the other hand, by definition we

cannot imagine surviving as a detached brain stem, because a detached brain stem would

82

Olson (1997), 141-142.

98

have no psychological features, no consciousness – there is nothing it is like to be a

brainstem. A detached-but-functioning brainstem may be a continuation of a given

animal life, as Olson claims, but it is not a continuation of a person’s life in any way that

matters to us. By prioritizing the brainstem and not the cerebrum, animalism departs

radically from what we care about when it comes to our survival. It manages to get the

intuitively correct result in cases where a whole brain is transplanted, because such a

transplant incorporates both the brainstem and the cerebrum, but when the two part ways,

animalism fails to accommodate our beliefs.

4 Conclusions

Although both psychological continuity views and physical continuity views have

much that can be said in their favor, the preceding discussion shows that none of the

accounts discussed is a good fit for our existing beliefs and practices concerning our own

survival through time. Neither psychological continuity alone nor physical continuity

alone is sufficient for survival per what follows from our existing beliefs about ourselves.

Thus, I propose a view which incorporates both psychological continuity and physical

continuity: the hybrid view.

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Chapter 3: A Hybrid View

The last chapter showed that each of non-reductionism, psychological continuity

views, and physical continuity views either conflict with basic beliefs about ourselves or

face serious metaphysical difficulties. In this chapter, I describe a hybrid view, which

calls for both physical and psychological continuity as necessary for the continuity of

persons. I argue that this view is metaphysically sound and a good fit for our actual

beliefs and practices about our own continuity.

1 Motivation for the Hybrid View

In the previous chapter, I argued that both physical continuity views and

psychological continuity views fail to accommodate our actual beliefs and practices

concerning our own continuity. It will be informative to more closely examine the nature

of their failures in this regard.

Parfit’s psychological-continuity-alone view is too broad to fit our actual beliefs

and practices. Because Parfit holds that an individual survives through any instance of

her psychology, an individual can survive through an occurrence of her psychology with

no causal link whatsoever to her original self. This conflicts with our beliefs and

practices concerning our identity: we are strongly disinclined to accept that we can

survive through the spontaneous occurrence of a psychology exactly identical to our own.

The conflict is most apparent when we consider how one ought rationally to behave in a

case where one’s psychology has spontaneously occurred elsewhere: Parfit’s conclusion

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is that, if my psychology occurs elsewhere, I should not object to the termination of this

instance of my psychology.83

In other words, I should not object to dying if there is

someone out there who bears my psychology. This conclusion is not clearly

unacceptable in all cases – it may be plausible in cases of teleportation, for instance. But

in other cases, such as when the duplication of one’s psychology occurs purely through

chance, without any causal connection between the original individual and the person

who bears their psychology, the conclusion that it becomes irrational to object to death is

wildly counterintuitive, so much so that it could perhaps be regarded as a reductio of the

view. Parfit’s view counts cases as survival which our beliefs and practices do not regard

as survival, and is thus too broad. To avoid Parfit’s extreme conclusion, one might move

to a psychological view which requires an appropriate causal connection between the

original psychology and any duplicates of it, in order for the survival of a duplicate to

count as survival of the individual. The positive account I defend here is precisely such a

view.

Animalist accounts of personal identity, such as Olson’s, fail to capture our actual

beliefs and practices in both directions: they exclude some cases where our beliefs and

practices say we survive, and include some cases where our beliefs and practices say we

do not survive. If my cerebrum is removed and transplanted, properly connected and

without loss of function, into another body, and the rest of my body (including the other

parts of my brain) is destroyed, our beliefs and practices say that I survive, as evidenced

by the transplant intuition. I become the occupant of the body into which my cerebrum

83

Parfit (1986), 280.

101

was transplanted, and survive there. Animalism holds that, although my cerebrum

remains functional and intact elsewhere, I died when my brainstem was destroyed.84

The

same conflict between our beliefs and practices and animalism occurs in any case where a

cerebrum remains functional and healthy, operating as usual, while the brainstem is

replaced or destroyed. Animalism holds that the individual dies in such cases, whereas

our intuitions about our own survival say that we survive. Animalism is thus too narrow

in this regard, for excluding as survival cases which we ordinarily regard as survival

because the psychology-bearing part of the brain survives.

Animalism also counts some cases as survival which our beliefs and practices

would call death: if my brainstem were removed, intact, from my head, and the rest of my

body and brain were destroyed, I would not survive per our ordinary beliefs and

practices. The fact that my brainstem is undamaged is no more evidence of my continued

existence in the relevant sense than the survival of one’s kidney, transplanted into another

body after one’s death, is evidence of the donor’s continued existence. Our beliefs and

practices simply do not afford the brainstem the sort of significance necessary for it to

make for continuity: it has more in common with the liver, the heart, the lungs, than it

does with the cerebrum in that regard. It is separable from the body, and if placed in

another body, may continue to operate as usual after the destruction of the body in which

it originated, but its doing so does not make for the survival of the individual whose body

it came from per our beliefs. Animalism disagrees. A brainstem, so long as it is still

operational, is the carrier of personal identity per animalism; the whole of the body but

84

Olson (1997), 142.

102

the brainstem can be removed, while the individual survives. In this way animalism is

too broad: it calls such cases, where the brainstem and nothing else survives, cases where

the individual survives, while our beliefs and practices characterize such cases as death.

A human animal remains alive in such circumstances, but the thing we identify ourselves

with is gone for good.

Animalism fails to fit with our beliefs and practices concerning our own

continuity due to its conflict with the transplant intuition, whereas Parfit’s psychology-

with-any-cause view allows cases where there is no causal connection between an

individual and the person she purportedly survives through. Animalism gets the results

we expect in cases where the cerebrum and the brainstem are not separated, whereas

Parfit’s view gets the results we expect in cases where there is an appropriate causal link

between an individual and the person she survives as. In other words, animalism yields

results that fit with our actual beliefs and practices where the psychology-bearing

cerebrum is not separated from the brainstem, and Parfit’s view yields such results when

there is a causal link between the individual and who she survives through, with the

continued existence of the physical brain one way that such a causal link can hold. When

animalism does not leave psychology behind, and when Parfit’s psychology-based view

does not leave physical continuity behind, the results fit best with our beliefs about our

own survival. This suggests an approach to our continuity that takes the better qualities

from each view but leaves aside the aspects which conflict with our beliefs about

ourselves and our survival through time. Thus, my proposal: a hybrid view, which calls

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for psychological continuity in virtue of physical continuity as the necessary and

sufficient feature for our continuity.

2 A Hybrid View

I will call the view I defend here the “hybrid view.” The hybrid view’s claim is

that some person x is continuous with some person y if and only if x and y are

psychologically continuous with one another in virtue of being physically continuous

with one another, where physical continuity consists roughly in being composed of much

of the same matter.85

In other words, if x and y have the same psychology in virtue of

having the same brain,86

then x and y are continuous with one another; in ordinary

language, we might say that x and y are the same person. Formally, then, the hybrid view

can be expressed as the claim that:

85

Peter Unger identifies an approach similar to this one as “a realistic account of our survival” (p. 139) in

Unger (1990), 139-169, although his primary focus is not on fully developing the account. The Embodied

Mind account of personal continuity described in McMahan (2002) is also quite similar to the view I

defend here, though McMahan emphasizes “the capacity to support consciousness or mental activity” (67-

68) rather than psychological continuity; the two may come apart at the beginning of life or sometimes at

the end. Arguments for such an account of identity as the only way to justify certain practical concerns,

such as moral responsibility, can be found in Glannon (1998), and suggested in D. Shoemaker (2007). I

will return to moral responsibility and its relationship to the hybrid view in the fifth chapter. In Thomson

(2008), 161, Thomson describes a view she calls the hybrid view of personal identity, but this view is not

the same as mine in spite of the common name.

86 Or more precisely, having the same brain parts which are responsible for the continued existence of the

psychology. Physical continuity will be defined in greater detail momentarily.

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Personal continuity holds between persons x and y iff

i) x is psychologically continuous with y,

ii) x is physically continuous with y, and

iii) x’s psychological continuity with y is in virtue of x’s physical continuity

with y.

Parfit’s definition of psychological continuity will serve: psychological continuity

is a relationship consisting of overlapping chains of strong psychological connectedness,

where psychological connectedness is defined as “the holding of particular direct

psychological connections.” Strong psychological connectedness occurs where a high

number of direct connections hold, though determining an exact threshold relevant for

this purpose is not feasible. Strong psychological connectedness, importantly, is not

transitive; a strong psychological connection exists between me-today and me-yesterday,

and between me-yesterday and me-two-days-ago and so on, but the result is not that I am

strongly psychologically connected to myself at any number of days or years ago.87

This eliminates difficulties resulting from earlier memories lost late in life. Right

now, as a graduate student working on my dissertation, I remember losing my first baby

tooth. But suppose that, at age 60, I no longer remember losing my first baby tooth. Yet

if, at 60, I remember being a graduate student working on my dissertation, there is

psychological continuity between this future version of me and me when I lost my first

tooth. Although the older me is not directly psychologically connected to the child who

lost her baby tooth, they are both psychologically connected to me now, as a graduate

student working on my dissertation, in that the graduate student remembers being the

child, and the older adult remembers being the graduate student. These are the sort of

87

Parfit (1986), 206.

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“overlapping chains” needed for the idea of psychological continuity across a lifetime to

be understood. We clearly do not carry all, or even most, of our psychological features

through our entire lives, and an understanding of psychological continuity which held

that the same psychological features must be present throughout a life to make for

personal continuity would be implausible. This understanding of psychological

continuity does not require that the same psychological features are present at all points

through life, just that connectedness holds between intermediate periods of life.

Physical continuity can be understood in an analogous way, as a relationship of

overlapping chains of strong physical connectedness, where physical connectedness

consists in having some of the same matter, with strong physical connectedness involving

sharing a high amount of the same matter, configured in approximately the same way.88

The mass of matter that composes my body now consists mostly of matter that composed

my body an hour ago, too, thus me-now is strongly physically connected to me-an-hour-

ago. By contrast, if my body currently includes a particle which was in Abraham

Lincoln’s body when he was shot, this does not mean that I stand in a relationship of

physical continuity with Abraham Lincoln. It is not only the low degree of overlap of

matter which prevents physical continuity here – even if it turned out that every bit of

matter that makes me up was a part of Abraham Lincoln when he was shot, the matter has

88

Physical continuity might be understood as short for ‘spatiotemporal physical continuity,’ the term Parfit

uses when he first explains the concept (Parfit (1986), 203). The ‘spatiotemporal continuity’ Shoemaker

discusses in S. Shoemaker (1963) as a criterion of identity for “ordinary material things” seems to be the

same relation I refer to as ‘physical continuity.’

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not been configured in approximately the same way between now and then. Because the

matter has not been body-composing in the meantime, I could share all my matter with

Abraham Lincoln without standing in a relationship of physical continuity with him. As

such, the configuration of matter, not just the identity of matter, bears on whether

physical continuity holds. As with psychological continuity, establishing a specific

threshold for how much physical connectedness is enough for physical continuity is not

feasible; it must suffice to say that physical connectedness is a matter of degree and a

high degree is required for physical continuity.

The need for overlapping chains of strong physical connectedness parallels the

need for overlapping chains of strong psychological connectedness. It is possible, even

probable, that none of the matter which composed me when I was ten years old is among

the matter that composes me now. However, there are overlapping chains of physical

connectedness which link me now to my ten-year-old self: she has some matter in

common with me at ten-and-a-half, ten-and-a-half with eleven, and so on. Although I

may have no matter in common with the ten-year-old, I have matter in common with

someone who has matter in common with someone who… and so on. Thus, ordinary

gains and losses of particles do not prevent the physical continuity requirement from

being met.89

If, however, all the matter of my body were to be replaced in an instant by

some quantum miracle, this would constitute a violation of the physical continuity

89

If this understanding of physical continuity is applied to the Ship of Theseus, the ship with all replaced

boards is not physically connected to the original ship, but is physically continuous with it due to the

overlapping chains of physical connectedness resulting from its gradual replacement of parts.

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requirement, because there would be no matter common to my body before this

occurrence and after.

The hybrid view does not only require both physical and psychological

continuity; it calls for psychological continuity in virtue of physical continuity. This

stipulation has two important implications. First, because the role of physical continuity

in the hybrid view is to preserve psychological continuity, the physical continuity

requirement can be limited to the parts of the body responsible for psychological

continuity. As Parfit puts it when characterizing physical continuity views: “What is

necessary is not the continued existence of the whole body, but the continued existence of

enough of the brain to be the brain of a living person.”90

So far as we know, this calls for

the continued existence of the cerebrum.91

Failure to meet the physical continuity

requirement as described in the preceding paragraphs by parts of the body other than the

cerebrum does not prevent psychological continuity, and thus is not relevant to this

90

Parfit (1986), 204.

91 Because transplanting cerebrums is not feasible at present, we cannot, perhaps, be sure that the cerebrum,

supported so that it remains functional, is sufficient for the continued existence of the psychology. It seems

feasible to replace the body parts which support the cerebrum, including even the brainstem itself, without

disrupting the cerebrum’s carrying of one’s psychology. For example, one might gradually replace my

brainstem with an artificial brainstem, eventually resulting in a completely artificial brainstem responsible

for coordinating the life-maintaining features of my body, including the cerebrum, as described in Olson

(1997), 141-142. Olson assumes that the brainstem could be replaced without disrupting the psychology

maintained by the cerebrum that brainstem originally supported. If this is incorrect, and the brainstem does

in fact play a role in the preservation of the psychology beyond simply allowing the cerebrum to function,

then the physical continuity criterion will also call for physical continuity of the brainstem.

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consideration. So long as my brain gains and loses matter in the normal way in

accordance with the physical connectedness requirement described above, it does not

violate the physical continuity requirement if the matter that composes the rest of my

body is spontaneously and instantly replaced with entirely different matter via quantum

miracle. Thus, the physical continuity requirement is limited to the parts of the body

necessary for preserving psychological continuity, which seems to be the cerebrum alone.

This is made evident by the fact that damage to the cerebrum results in changes to or the

complete eradication of the psychology, whereas changes to other parts of the body, even

other parts of the brain, do not result directly in such changes to the psychology.

The second implication of this requirement is that cases where both physical and

psychological continuity occur, but the psychological continuity is not due to the physical

continuity, do not meet the necessary condition and thus do not count as cases of personal

continuity per the hybrid view. When might this criterion be violated? Such a violation

occurs when the physical continuity requirement is met, and the psychological continuity

requirement is met, but the fact that the psychological continuity requirement is met is

not due to the physical continuity requirement but due to some other cause. For instance:

at the hands of a nefarious neurosurgeon who has taken interest in the philosophical

concept of personal identity, Harold’s brain is scanned, and then ‘wiped clean’: his

psychology is gone – not hidden away under another psychology, but truly gone from his

brain. The result is a living human with no memories, beliefs, desires, personality, or any

other psychological features. Next, the neurosurgeon alters Harold’s brain again: by

altering it on the microphysical level, he causes this ‘blank’ brain to have Harold’s

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memories, beliefs, desires, and so on, just as Harold had them at the time of the scan prior

to his mind-wipe. The same matter (give or take the particles gained and lost in the usual

way) composes Harold’s brain that composed it before the wipe, and the psychology

which Harold’s brain bears after the second procedure is identical to Harold’s psychology

before the first procedure.

Per the hybrid view, the person who wakes up following the second procedure is

not continuous with Harold, in spite of having a brain, which was continuously a brain,

made of the same matter more-or-less as Harold’s brain before the first procedure, and

bearing the psychology Harold had before the first procedure. In spite of possessing both

physical and psychological continuity with Harold pre-procedure, the person who wakes

after the second procedure does not stand in a relationship of psychological continuity

with Harold in virtue of his physical continuity with Harold. The nefarious neurosurgeon

could have stopped after the first procedure, and the result would be a person who has

Harold’s brain, physically, but not Harold’s psychology. The fact that Harold-after-the-

second-procedure is psychologically continuous with Harold-before-the-first-procedure is

not due to the fact that they have the same matter making up their brain, but to the fact

that the neurosurgeon caused Harold-after-the-second-procedure to have the psychology

of Harold-before-the-first-procedure. The neurosurgeon did alter the brain so that it had

Harold’s psychology again, but he could have done otherwise, which would have resulted

in physical continuity but not psychological continuity between Harold before and after

the pair of procedures. The presence of Harold’s psychology in Harold’s brain, following

the second procedure, is a result of the neurosurgeon’s meddling, not a result of the brain

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continuously bearing Harold’s psychology. Harold’s psychology was separated from

Harold’s brain, and per the hybrid view, the psychology and the physical brain cannot be

separated in this way without ‘breaking’ the continuity relationship.

The view does not entail that a psychology needs to be “active” or “in charge” at

all times to be present, however. In the example above, Harold’s psychology was truly

wiped clean from his brain: it wasn’t dormant, repressed, or buried under some other

psychology – it was truly gone, and then restored by a second act of brain-alteration from

an external source. The distinction between these types of mind-wipes is noted by Perry,

the variety which results in the complete eradication of a psychology being called a

“brain-zap.”92

In a brain-zap, the psychology is truly erased, not merely relegated to

some backwater of the brain, intact but inaccessible, as they are in what Perry calls

“information overlay.” Information overlay is the sort of psychology erasure typical of

fictional depictions of amnesia, though there it is usually memories only, not other

psychological features, which are rendered inaccessible: “The picture is of a person

whose memories are inaccessible, but, in some sense, still there. The disposition to

remember is present, but not triggered by the ordinary conditions. Photographs, diaries,

and the sight of loved ones will not do the trick; perhaps a fortuitous blow on the head or

electric shock therapy will.”93

By contrast, in a brain zap, “efforts to trigger the

disposition [to remember] would be to no avail because the disposition is not there to be

92

Perry (2008b), 339.

93 Perry (2008b), 339.

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triggered.”94

Thus, whether a brain-zap has occurred depends upon whether the

psychology is truly gone or not: if the psychology is truly gone, not merely rendered

inaccessible but eradicated from the brain, then a brain-zap has occurred; otherwise, a

brain-zap is not the correct description for the case.

In any case where a brain-zap occurs, the person whose psychology was zapped

away is killed per the hybrid view.95

That person’s psychology, having been erased from

their brain, is gone, and with it, so are they, regardless of whether a psychology just like

theirs is later restored to the very same brain, as in Harold’s case. Harold-after-the-

second-procedure should be understood as an artificially-created duplicate who happens

94

Perry (2008b), 339.

95 One may be concerned about the epistemic implications of this claim, on the grounds that it may not be

possible for us to determine whether a particular case of lost psychology is a mere information overlay or a

brain-zap. The fact that attempts to recover the lost psychological features are ineffective is not necessarily

evidence that the lost psychological features are not still present in the brain. As such, there may be

situations where we are not certain whether a person is dead or not, if we are not sure whether their lost

psychological features are truly gone, as in a brain zap, or merely rendered inaccessible, as in information

overlay.

This uncertainty does not undermine the hybrid view: it merely means that there will be some cases where

we are not certain whether a person has survived or not. If we had all the facts – if we knew whether there

had been a brain-zap or an information overlay – we could assess whether the person still existed; without

all the facts we will be uncertain. This can be considered analogous to the question of whether a missing

person is alive or dead: lacking all the facts about the case, we cannot be certain if they are living or dead.

If we had all the facts, it would be obvious, but if we don’t, uncertainty is the appropriate response.

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to have been created using the original’s materials. He is distinct from Harold-before-

the-first-procedure; Harold-before was destroyed when his psychology was wiped.

2.1 The Hybrid View at Work

As an initial fit for our ordinary beliefs and practices about our continuity, the

hybrid view does as well or better than its competitors. In ordinary, everyday cases, both

brain and psychology remain in a single human body, united as a single person, and thus

the hybrid view confirms that, for instance, my ten-year-old self is continuous with me

now, because the child is psychologically continuous with me now in virtue of being

physically continuous with me now. There is a continuous series of overlapping chains

of psychological connectedness, grounded in a continuous series of overlapping chains of

physical connectedness, which links my ten-year-old self to me now. The hybrid view

gets it right in the ordinary cases, but this is not saying much, as most of the views

discussed in the previous chapter either get the simple cases right, or can easily be

interpreted in such a way that they do.

The hybrid view also fits with the transplant intuition. Because the hybrid view

calls for physical continuity of the brain – specifically, the portions of the brain

responsible for psychological continuity – the hybrid view agrees with the transplant

intuition that where my functioning brain goes, I go. It bears the caveat that, if a brain-

zap occurs in the course of the transplant, then the psychological continuity requirement

is not met and the resulting person is not continuous with the previous person. However,

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the same is true if a brain-zap occurs in any situation, so this does not contradict the

transplant intuition specifically.

In fact, the transplant intuition doesn’t seem to entail anything about where I go if

my brain is moved but significantly altered in the process. If, for instance, my brain is

removed from my head, and then the matter that makes it up is rearranged on the atomic

level to compose a small turkey breast, then placed in someone else’s brainless head, it is

obvious that no person results from the combination of brainless body and turkey breast,

and therefore no personal continuity can be involved. If the matter that makes up a brain

ceases to be brain-composing (whether during transplant or otherwise), continuity is

violated, even if the same matter composes the resulting non-brain object. This is also

the case if the matter ceases to be brain-composing along the way, but is restored to a

brain-composing state before being transplanted. That is, if my brain is removed from

my head, rearranged on a microphysical level to be a turkey breast, and then rearranged

back into a brain, the physical continuity requirement will be broken, and personal

continuity will not result. As stated, this stipulation does not violate the transplant

intuition, because the transplant intuition does not tell us anything about what results

when a brain is significantly altered prior to transplant.

So the hybrid view fits with everyday cases where continuity is not confusing, and

fits with the transplant intuition. However, as noted, most views do. What makes the

hybrid view a better candidate as an answer to the question of what metaphysically sound

view best fits our actual beliefs and practices? The hybrid view stands out when we

begin to address the unusual cases: its results in various nonstandard cases are more

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plausible and a better fit with our actual beliefs and practices concerning our continuity

than any of the contender views discussed in the preceding chapter. In many cases, the

hybrid view’s results are an immediate fit for the intuitively ‘right’ answer about who is

who; in others, although the hybrid view’s result may not seem to be a good match at

first, its failure to match can be explained by revealing a weakness or inconsistency in the

intuitive response to the case.

2.1.1 Brain Damage

According to the hybrid view, psychological continuity in virtue of physical

continuity is the criterion of our continuity. As a result, whenever either the physical

continuity requirement or the psychological continuity requirement is broken, personal

continuity is ruled out. Accordingly, a brain injury which results in the loss of

psychological continuity will also result in the loss of personal continuity.

How does this play out in practice? The result is that whenever a person loses

enough of their psychology that they can no longer be said to have overlapping chains of

strong psychological connectedness linking them to their former self, they cease to be

that person (though they do not necessarily cease to be a person at all).96

Thus, a

condition that results in the loss of psychological features, including memory, desires,

beliefs and personality traits can result in the end of an individual’s existence long before

her body dies. For example, if a person suffering from dementia loses enough of her

96

Although I am here supposing that the loss of psychology is the result of injury or illness, this situation is

not importantly different from Parfit’s Psychological Spectrum case (Parfit (1986), 231-233).

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psychological features that she can no longer be considered psychologically connected to

her former self (I will not attempt to set a specific threshold for “enough”), she has

ceased to exist, according to the hybrid view.

On the one hand, this view seems to fit with many of our practices. When

someone has lost a majority of their psychological features, one does not need to be a

philosopher to believe that that person is gone, even if their body is still alive. This sort

of sentiment is not uncommon among those who have dealt with the slow mental decline

of an aging family member. Although the human being, the organism, still lives on, and

as such a human being numerically identical to one’s relative still exists, the qualities that

might be said to ‘make them who they are’ are no longer present. This attitude is also

reflected in the fact that a distinction is drawn between brain death and death, simpliciter:

a body can live on while no person ‘inhabits’ it.97

As such, the belief that a person can be

gone for good while their body lives on is not an obscure notion only a philosopher could

believe. Thus, the hybrid view fits our pre-philosophical understanding of such

situations.

However, there is also a somewhat surprising result here: if the mental damage is

such that it has destroyed enough of the victim’s psychology that the psychological

continuity criterion is no longer met, but has not rendered the victim a non-person, then

the occupant of the victim’s body is a new person. This result is peculiar-sounding, to be

97

Although many in and out of philosophy consider brain death to be death, as discussed in Green and

Wikler (1980), the fact that we can even assert or question whether brain death and death (simpliciter) are

the same thing shows that distinguishing between brain death and death simpliciter is possible.

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sure, but does not seem to be so wild that it cannot be accepted.98

In a case where the

person is gone, but the requirements for personhood (capability for rational thought and

the like) are met, the result must be a new person. If the original person is truly gone, as

the case stipulates, the occupant of their body cannot be them. Yet, if the occupant of the

body does meet personhood requirements, then we cannot say that the occupant of their

body is no person. There are no grounds for saying that in such a case the occupant is

some other previously-existing person, so the resulting person must be someone new.99

This conclusion seems odd, but is a plausible way of interpreting such a situation.

Imagine that a young woman, Ivy, suffers from severe brain damage, such that she is no

longer psychologically continuous with herself prior to the injury. It is not only Ivy’s

memories that are gone. Psychological connectedness, the overlapping relation which

makes for psychological continuity, involves personality, beliefs, desires, intentions, and

other psychological features, not just memories. The fact that Ivy-after is not

98

Thomson complains that it is “really an odd idea that tinkering with someone’s brain – or feeding a

person a drug – might result in a new person” (Thomson (2008), 163) but does not seem to offer any

substantial reason to reject the possibility, beyond her dissatisfaction with the idea.

99 Animalism faces a similar, and arguably more serious problem: if my brainstem is removed and

immediately replaced by an artificial brainstem, so quickly that the disruption of life-sustaining function

causes no damage, I am killed by this procedure as soon as the original brainstem is destroyed, in spite of

the fact that I may (seem to) live on for many years without any noticeable change in any qualities that

matter to me. Olson discusses this in Olson (1997), 140-142. The difficulty of claiming that Ivy-after is a

new person is small compared to the claim that a body part with no apparent role in the maintenance of

what makes us us could result in death.

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psychologically continuous with her past self means that Ivy is not a victim of fictional

amnesia, but of a brain-zap. Her psychological features, not just her memory, are gone,

and they are truly erased, not merely inaccessible.

As argued in the previous chapter, Ivy-after should not be understood as Ivy. Ivy

does not survive the brain damage; the fact that it entirely eradicated her psychology

means that the injury was fatal to Ivy. As such, Ivy-after cannot be identified as Ivy. Ivy

is gone. Now suppose that, in spite of the severity of her injury, Ivy-after still fully meets

the criteria for personhood. She is self-aware, capable of rational thought and agency,

and so forth. There are no plausible grounds for denying that Ivy is a person in the

relevant sense. Yet Ivy-after is, as established, not Ivy; Ivy is gone. There is no other

previously existing person we can plausibly identify Ivy-after with – she has not, for

instance, taken on the psychological features of her neighbor Mr. Smith. If she is not Ivy,

and she is not some other previously existing person, but she is a person, she must be a

new person. Although odd-sounding when described in the abstract, this conclusion

follows naturally, without any suspect maneuvers, from two premises which I think

ordinary people are inclined to accept, and the case of Ivy should demonstrate that it is

the most plausible way to deal with such a case. Thus, this result does not show that the

hybrid view is a poor fit for our actual beliefs, since our actual beliefs, carried out

logically, have the same result as the hybrid view.

One may insist that Ivy-after is Ivy on the grounds of other people’s relationships

to her, particularly familiar relations. Shouldn’t Ivy’s parents or children still care for

her, even though she is psychologically entirely unlike their relative prior to the brain

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injury? The intuition that they should is strong, but can be explained by the distinctive

nature of familial relationships as opposed to other interpersonal relationships. Scott

Campbell argues this point, noting that all familial relationships begin as relationships

with strangers – parents do not “accept a son or daughter on the basis of whether you

know them or like the sort of person they are,”100

but because they are the child’s parents.

Family relationships are unlike other interpersonal relationships in this regard: they are

based in biological features rather than personal preferences concerning psychological

features. As a result, the family relation (“daughter” or “sister”, etc.) that one stands in to

others may plausibly be thought to continue even where the individual does not stand in a

relationship of personal continuity to the daughter her relatives knew. 101

In short, Ivy’s

parents (for instance) may accurately regard her as their daughter even if Ivy-after is not

the same person as Ivy. Because of their basis in biological facts102

, family relationships

may plausibly concern a relationship more like the identity of human animals, in spite of

the fact that most of our beliefs and practices concerning personal continuity

demonstrably do not, as argued in the previous chapter. Thus, the fact that Ivy’s

relatives may persist in regarding her as their daughter does not demonstrate that Ivy-

after is Ivy for any other purpose, including personal continuity.

100

Campbell (2004), 25.

101 Campbell (2004).

102 The fact that an adoptive relative is likely to feel the same as a biological relative in this regard does not

necessarily undermine this line of reasoning, as it is plausible to suppose that family relationships in

adoptive families mimic family relationships in biological families.

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Another major category of brain injury worth evaluating the hybrid view’s

response to is injury which results in the total destruction or removal of part of the brain,

while the rest continues to function. There are actual cases like this, where large parts of

the brain are removed, but the person lives and continues to meet personhood

requirements.103

For simplicity’s sake, I will call these half-brain cases, although the

removed portion may be less or somewhat more than half.

According to the hybrid view, so long as the half-brained person meets the three

requirements of the hybrid view – psychological continuity, physical continuity, and the

psychological continuity is in virtue of the physical continuity – then personal continuity

is maintained. As long as psychological continuity and physical continuity remain, and

there is no interference to compromise the dependent relationship between the

psychological continuity and the physical continuity, the hybrid view holds that the

person with the partial brain stands in a relationship of personal continuity with that

person prior to the removal of part of the brain. This is the intuitively correct result.

Although removal of major portions of the brain may result in significant impairment or

changes to the personality, it is possible for such a procedure to take place without

violation of the psychological continuity requirement. It is possible that, either

immediately or after some period of recovery, the resulting person still stands in a

relationship of strong psychological connectedness to his former self. Whenever this is

true, the hybrid view says that the person stands in a relationship of personal continuity

with himself prior to the loss of part of his brain. Common sense agrees: while major

103

Parfit (1986), 254.

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brain damage can be such that it destroys the person who existed before the damage, it

need not do so; when a person with half of his brain is sufficiently like the person he was

before losing half his brain, common sense tells us that is him, the same person he was

before. As elsewhere, I will not attempt to locate the exact threshold between survival

and non-survival, but merely note that the real half-brain cases show us that in at least

some cases, reaching the threshold at which survival definitely occurs is possible with

only half of a brain.

2.1.2 Duplication

The hybrid view requires psychological continuity based in physical continuity.

As a result, any case which involves psychological continuity but not physical continuity

is not a case of personal continuity according to the hybrid view. Thus, any case

involving duplication that does not result from a division of the relevant matter (the

matter which composes the cerebrum) fails to be a case of personal continuity according

to the hybrid view. What implications does this have?

Cases of duplication without physical continuity are not foreign to us: one

familiar form of such a case is Parfit’s teleportation as described in Chapter One, where a

person seems to travel from one location to another by having an exact copy formed at

the destination from local matter. The hybrid view rejects this interpretation of so-called

teleportation: the person formed at the destination out of local matter does not meet the

physical continuity requirement with the person who entered the teleporter at the site of

departure, and thus is not the same person who entered the teleporter according to the

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hybrid view. Teleportation which involves dissolution of the body that enters the

teleporter at the departure site (which seems to be the norm in science fiction, and is the

form that Parfit describes104

) is not actually a novel way to travel; it is a novel way to die.

Teleportation which does not involve destruction of the body in the departing teleporter is

not travel, either: it is a way to bring into existence a new person who believes they are

you, although they are incorrect in this belief.

On the surface, then, the hybrid view seems to have results that disagree with our

ordinary beliefs. Teleportation is a familiar concept in science fiction; it’s something we

tend to think of as possible, prevented for the time being by the limits of our current

technology, not by metaphysics. However, ruling out the possibility of teleportation with

personal continuity is not so contrary to our ordinary beliefs as it might seem. Because

teleportation, as we have imagined it, occurs by creating a perfect duplicate and

destroying the original, we can accept teleportation as a way to continue on only if we

can accept duplication as a way to continue on. We reject duplication as a way to

continue on, as evidenced by our response to cases where the original is not destroyed.

Teleportation is duplication; duplication is not continuity; therefore teleportation is not

continuity. This follows in a direct way from our existing beliefs; any person who

reflects on her beliefs about personal continuity will see that this reasoning follows from

the beliefs we have about teleportation and duplication. One does not need to be a

104

“The Scanner here on Earth will destroy my brain and body, while recording the exact states of all my

cells… [The Replicator on Mars] will then create, out of new matter, a brain and body exactly like mine.”

Parfit (1986), 199.

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philosopher to see that teleportation as a means of preserving continuity is not possible,

given our assumptions. This is reflected in non-philosophical discussions of

teleportation. For example, an article on humor website Cracked.com stated the

following:

A teleporter wouldn't actually break down your atoms and then shoot

those same atoms thousands of miles through the air; even if it were

possible, there'd be no reason to do it. It would instead just grab Hydrogen

and Oxygen atoms from out of the air and assemble you out of those (one

Hydrogen atom is the same as another, after all).

In other words, teleporters would work more like fax machines than mail.

It transmits a signal and the machine on the other end spits out a copy.

Only instead of a copy of a letter, it's a copy of a person, right down to all

their thoughts and memories and here the original is destroyed. […]

Are you grasping the weirdness of this? The original is destroyed. That

means when you step into a teleporter, you die. But, the rest of the world

won't know you died, because a copy of you will step out of the other end

of the machine. It won't be you, though, it'll be another you that happens to

share your memories. To the outside observer the thing will always work

fine, and the thing that steps out of the receiving end will think it worked

fine. The one person who knows it didn't worked fine, can't tell anyone

because they … died via total atomization the moment they stepped into

the machine.

So, the first time Captain Kirk used the teleportation device to beam down

to an alien planet, he was basically resigning himself to an immediate

death and hoping that his twin would carry out the mission for him.105

What significance do a humor website’s remarks on the subject have for the hybrid view?

The site is certainly not oriented towards philosophers. That such a website can argue

105

Cracked.com (2007).

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plausibly that teleportation is, upon closer examination, a way to die rather than a way to

travel suggests that our ordinary beliefs, when closely examined, may not support the

possibility of travel by teleportation after all. It may be that travel by teleportation is, like

many other concepts in science fiction, something that sounds plausible at first, but falls

apart once one considers it in depth. Failure to fit our most superficial, unexamined

beliefs about personal continuity is not a weakness for the hybrid view – the hybrid view

ought to fit our best, most plausible, most coherent beliefs about personal continuity, and

it is not clear that the belief about the possibility of teleportation as transportation is

among these. As such, an inability to allow for the possibility of travel through

teleportation is not necessarily a problem for the hybrid view.

The hybrid view also denies the possibility of personal continuity through a

duplicate brought about by any other means; teleportation is just one way that a perfect

duplicate can come into existence. Any person x who is psychologically continuous with

a person y but not physically continuous with person y fails to meet the criteria for

personal continuity set out by the hybrid view. This is true regardless of what happens to

person y at the time the duplicate comes into existence or after – for instance, the fact

that, in the basic teleportation case, person y is destroyed at the very moment person x

comes into being does not make person x a candidate for personal continuity with person

y. Just in virtue of lacking physical continuity, in spite of being a perfect physical

duplicate, person x cannot be continuous with person y according to the hybrid view.

The same holds true for duplicates created by means other than teleportation.

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2.1.3 Fission

Fission should here be understood as a process in which one person divides into

two (or more) people. Parfit describes fission with a case where his body has been fatally

injured, while the brains of his two brothers are fatally injured. Parfit’s brain is divided,

and one hemisphere is transplanted into the body of each brother, appropriately attached

so that it can function.106

Parfit includes the stipulation that the recipients are his brothers

to avoid concerns about the similarity of the receiving body to the donor body, but any

case where a single brain is divided so that it operates separately from the other

hemisphere could be a case of fission. Although this initially seems like a merely-

possible scenario, fission of a sort does actually occur: some medical conditions, such as

severe epilepsy, are treated by destroying the connection between the hemispheres of the

brain, the corpus callosum. The result of the severing of the corpus callosum is two

distinct, independently-operating consciousnesses, each composed of half of a brain,

sharing a single body. Because they are independent of one another, these two

consciousnesses can have different psychological features from one another, as evidenced

by Parfit’s mention of a case of a split-brain patient who reported that sometimes, when

he hugged his wife, his other hand would push her away.107

This clearly suggests that the

two consciousnesses had, at the very least, different desires – one wishing to hug his

wife, the other wishing not to – thus showing that they have different psychological

features to at least some extent. Split-brain patients also experience different sensory

106

Parfit (1986), 254-255.

107 Parfit (1986), 245-246.

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inputs, with each hemisphere unaware of the sensory inputs received by the other

hemisphere.108

The possibility of fission is also supported by real-world half-brain cases, where a

person survives the destruction or removal of a large portion of her brain. These cases

and the epilepsy cases show that it is fully possible for a person – not merely a human,

but a person, with all the psychological characteristics that entails – to live with only half

of a brain. On the assumption that successful brain transplants will someday be possible,

this means that fission is a very real possibility in a way that some other hypothetical

problem cases may not be. We already know a person can live with half a brain, and it

seems possible that brain transplants will be within the scope of medical capabilities at

some point in the conceivable future: the hemispheres of the brain could be separated,

and each half transplanted successfully into its own brainless body. Thus, although it is

out of our reach now, fission cases are ones which could eventually be a part of our actual

experience.

How does the hybrid view handle fission cases? Here, the relevant consideration

seems to be how much of the brain is needed to meet the hybrid view’s requirements.

Real world half-brain cases provide the answer to this question: half is certainly enough,

and even less may be sufficient in some cases. Nothing about removing part of a brain

necessarily violates any of the three requirements of the hybrid view (although such a

removal could violate one of the requirements), so it should be fully possible for a half-

brain to allow for psychological continuity in virtue of physical continuity.

108

Parfit (1986), p. 245.

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If it is possible to meet the hybrid view’s criteria for personal continuity with only

half a brain, as real world half-brain cases show it is, then it should also be possible to

divide a healthy brain in two, transplanting each half into a different body. (Such a

procedure is unlikely to be ethically justified, but it is possible that such a thing could be

done.) This is what ‘fission’ refers to: a brain is divided, and both halves continue on

independent of one another.

Fission cases lead to difficulties that simple half-brain cases do not: in an ordinary

half-brain case, one half of the brain is destroyed or damaged such that it no longer

functions; as such, there is only one plausible candidate for personal continuity

afterwards. Only half of the brain survives, so if the person whose brain it is survives,

she must survive through that remaining half. In fission cases, by contrast, both halves

survive, so there is not a single, unique candidate for personal continuity following the

division as there is when division is a result of the destruction of one half of the brain.

The hybrid view requires psychological continuity in virtue of physical

continuity, and real world half-brain cases show that it is possible for this condition to be

met with half a brain. Thus, it is possible for two halves, coexisting independent of one

another, to each meet this requirement. As a result, per the hybrid view, there can be two

distinct humans with half-brains who each stand in a relationship of personal continuity

with a single human who has a whole brain.

In one sense this result is counterintuitive: we tend to think that, since there is

only one of each of us, there can be only one person at a given time who stands in a

relationship of personal continuity with us. However, it has been argued repeatedly and

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effectively that there are no good grounds for claiming that we could survive as either

half, but not both, yet the continued existence of both hemispheres does not seem like the

sort of thing which could cause one to die when the survival of only one working

hemisphere makes for survival.109

Consider a fission case where one person, Jim, has his

brain divided, and each half is placed in a brainless body. Call the resulting two humans

Lefty and Righty, based on which half of the brain they possess. Real world half-brain

cases show that it is possible to survive with only half a brain, so surely Jim survives this

division – a single half-brain would be enough for him to survive, so either Lefty or

Righty’s existence is sufficient for Jim’s survival. Meanwhile, it would be bizarre to say

that Jim does not survive on the grounds that both halves of his brain are still around. If

he could survive as Lefty, as half-brain cases show he must, then he can survive as Lefty

even in a world where Righty is still out there, not destroyed. The same, of course, can

be said of Righty. Simultaneously, there are no good reasons to say that Jim survives as

Lefty but not as Righty, or as Righty but not as Lefty. Each of Righty and Lefty has an

equally good claim on ‘being Jim.’ Jim survives through a half-brain, and each of Righty

and Lefty are a half-brain, so it seems that Jim must survive through both. Here, again,

we arrive at a conclusion which follows in a very plausible way from premises which are

natural to accept. No obscure philosophical reasoning was necessary to get us here.

Thus, although it may seem odd at first blush, Jim’s survival as both Righty and Lefty

109

This sort of case is discussed by, for example, Parfit (2008), 200-201; Parfit (1986), 254-256; Perry

(2008b), 329-330, describing Williams (1957), 238-239; S. Shoemaker (1984), 85-85 and 119-120.

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follows clearly and directly from the facts and our ordinary beliefs about what would

happen in such cases.

The hybrid view supports this conclusion. The degree of continuity necessary for

meeting the requirements of the hybrid view’s three criteria can be met by a half-brain;

real world cases show this. The continued existence of the other half, meanwhile, in no

way undermines the fact that a single half of the brain meets these criteria; no facts about

Righty can impact whether Lefty has psychological continuity in virtue of physical

continuity with Jim, and likewise for Righty. Thus, each of two halves is independently

able to meet the three criteria, meaning that each of the two humans with the halves

stands in a relationship of personal continuity with the original person.

Of course, Lefty and Righty themselves do not stand in a relationship of personal

continuity with one another. Lefty and Righty are not physically continuous with one

another, so they cannot stand in a relationship of personal continuity per the hybrid view.

Further, although their psychologies could be quite similar, depending on the

configuration of Jim’s brain prior to the division (theoretically, Jim’s two hemispheres

could have been qualitatively identical110

), they will begin to diverge immediately

following their placement in separate bodies. They will have different memories just in

virtue of looking out eyes that are in different locations, for instance, and the differences

will only become larger from there.

Thus, the hybrid view leaves us in a position where two persons, Lefty and

Righty, are each personally continuous with one person, Jim, but are not personally

110

Parfit (1986), 255.

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continuous with one another. In casual speech, we might want to say that Jim is Lefty,

Lefty is Jim, and Jim is Righty, and Righty is Jim, but that Lefty is not Righty and Righty

is not Lefty. The potential difficulty with this should be obvious: if we understand this

“is” to be the “is” of identity, these claims contradict one another. If Jim = Righty and

Jim = Lefty, then Righty = Lefty. Thus, we must either concede that Righty is Lefty, in

the identity sense of “is,” or give up identity. It is demonstrably false that Righty is

identical to Lefty – they have different spatial locations, different bodies, and their

psychologies, even if identical at first, will begin diverging as soon as they regain

consciousness following the hemisphere transplants. Thus, it seems that the hybrid view

must reject strict numerical identity as the criterion of personal continuity, just as any

other view which allows for the possibility of fission must.111

Identity is necessarily

transitive, while as fission cases (among others) show, personal continuity is not

transitive. The fact that Jim is continuous with Righty and Jim is continuous with Lefty

does not entail that Lefty is continuous with Righty.112

However, this result does not undermine the hybrid view as the account of

personal continuity which best fits our beliefs and practices. Rather, the hybrid view’s

111

Parfit is explicit in his rejection of identity as relevant to our continued survival, as discussed in his

“Why Our Identity is Not What Matters” chapter of Parfit (1986), 245-280. Locke also acknowledges this

point in his distinction between whether two individual are “the same person,” or merely “whether it be the

same identical substance” (Locke (2008), 40).

112 This problem is discussed in Perry (1972); S. Shoemaker (1984), 85; Wiggins (1967), 53; and in Parfit

(1986), 253-258.

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result serves to demonstrate that our beliefs and practices do not entail that strict

numerical identity is the criterion of personal continuity.

Considering the role that strict numerical identity played in the steps leading to

this conclusion help to reveal this point. Real-world half-brain cases show that an

individual can continue to function as a person after the destruction of half of his brain,

and per our beliefs and practices, such an individual will still be “the same person,”

unless the destruction of the brain resulted in psychological changes more extreme than

those which must result from such an injury. But although we think that a half-brain

person can be the same person before and after the loss of a hemisphere, the brain of a

half-brain person, following the loss of a hemisphere, is not identical to his brain prior to

the loss of the hemisphere – it is identical to a part of his brain prior to the loss of the

hemisphere. It is the same brain in that it is all that remains of the original brain, but it is

not identical, because the original brain included another hemisphere which the half-brain

does not. The original brain is identical to the half-brain plus the destroyed hemisphere.

If a half-brain person can be the same person he was before the loss of a hemisphere, as

our beliefs and practices say he can, then strict numerical identity of the physical brain is

not necessary for being the same person, meaning that strict numerical identity is not

necessary for personal continuity. Having a part of the original brain, if it is large

enough, is sufficient for being the same person, even though having a part of the original

brain does not entail strict numerical identity of the brain when the part is not the whole.

This conclusion then carries over to the fission cases. Neither the left hemisphere

of Jim’s brain, now in Lefty’s head, nor the right hemisphere of Jim’s brain, now in

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Righty’s head, is identical to Jim’s original brain, but together, those two hemispheres are

identical to Jim’s brain. Lefty, Righty and Jim are not identical to one another, but we

can still say that Jim is the same person as Righty, and the same person as Lefty, just as

we can in half-brain cases. Yet we are not forced to say that Lefty and Righty are the

same person, because they do not have any parts in common. Each has a part of Jim’s

brain, which half-brain cases show is enough to be considered the same person, but

because they have no parts in common, Lefty and Righty are not the same person.

2.1.4 Fusion

Another hypothetical problem case for personal identity is fusion, in which parts

from two distinct brains are combined in a single head and connected appropriately.

Fusion is somewhat further out of reach than fission, perhaps, given that there is no way

at present to unite separated parts of a brain so that they work together as a single

functioning brain, even when the parts come from the same brain: for instance, a severed

or absent corpus callosum cannot, at present, be recreated.113

However, our inability to

link two hemispheres so that they function as a single whole brain seems to be limited by

our current neurological and medical technology, not by any deep truth about ourselves.

Although fusion remains a hypothetical case, and one that is likely to remain hypothetical

longer than fission, there is no reason to think that it will not be possible in the actual

world at some point in the distant future, given sufficient advances in medical

technology. Thus, it is worth considering how the hybrid view addresses such cases.

113

National Organization for Disorders of the Corpus Callosum (2013).

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To illustrate the possibility of fusion, suppose that two women, Helen and Irene,

each have their brains split into two. As it happens, both Helen and Irene have the

improbable condition of hemisphere duplication: each woman has a left hemisphere

which is identical to her right hemisphere. (This stipulation allows the fusion case to

avoid considerations about which half of the brain is dominant. When the two

hemispheres are identical for both women, we can avoid concerns about whether one

hemisphere was responsible for most of the psychological features relevant to continuity.)

The left hemisphere of Helen’s brain and the right hemisphere of Irene’s brain are placed

together into a body with no brain and connected to the body so that they can function

normally. The psychological features of both women remain intact. Call the resulting

individual Jane.

According to the hybrid view, Jane stands in a relationship of personal continuity

with both Helen and Irene. As with fission, this is made evident by information from

actual half-brain cases: half a brain is sufficient for personal continuity, and we have

stipulated that there was no loss of psychological features in the transplant of either

hemisphere. Psychological continuity holds in virtue of physical continuity here. In such

a case, Helen could survive as only her left hemisphere transplanted into Jane’s head

alone, and Irene could survive as only her right hemisphere transplanted into Jane’s head

alone. The fact that these hemispheres share the cranial cavity with something else (the

other woman’s other hemisphere) does not seem to be the sort of thing that could

undermine the fact that the condition under which each woman would survive is met. So

Helen survives the transplant as Jane, and Irene survives the transplant as Jane.

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The obvious question in such a case is whether Jane should be regarded as one

person, or two persons sharing a single body. Since we have established that Helen, one

person, could survive as Jane if her left hemisphere had been transplanted alone into

Jane’s head, and Irene, one person, could survive as Jane if her right hemisphere had been

transplanted alone into Jane’s head, and Helen is not identical to Irene, it seems that the

result should be that Jane’s head houses two distinct entities, each of which is a person in

its own right. Irene and Helen remain distinct people, but happen to share a single body,

right down to the skull.

This answer may seem peculiar when contrasted with ordinary brains. After all,

an ordinary brain also consists of two distinct hemispheres, each of which is capable of

functioning as a person on its own, as evidenced by real half-brain cases. The relevant

difference between an ordinary brain and Jane’s situation seems to be that, in an ordinary

brain, the two hemispheres are not in fact each hosting a person independently, although

they have the capability to do so. In cases where the connection between the brain’s two

hemispheres is severed, the result seems to be that two independent person-composing

hemispheres exist in a single skull, even though the hemispheres were not independently-

person composing, merely potentially independently person-hosting, prior to their

division. When an ordinary brain has its connection between hemispheres severed, the

result is two independent consciousnesses, each person-composing, sharing a single skull:

in other words, two persons sharing one body. This shows that it is possible for two

persons to share a single body, and the fact that Helen’s half-brain and Irene’s half-brain

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are, in fact, each hosting a person shows that Jane’s situation is also a case of two persons

sharing a single body.

One may hesitate over whether cases where the connection between hemispheres

is severed are really cases of two people sharing a body. Accepting this is not necessary,

however, as there is other evidence to show that two people can share one body. The

existence of conjoined twins who share most of a body – thought not so much as Helen

and Irene post-transplant – supports the idea that a single body can belong to two distinct

people. Language provides a slight stumbling point here: when conjoined twins share

most of their body parts, terms like “two-headed baby” are more likely to be used than

“two babies with one body.” Nonetheless, it would be a mistake to give this linguistic

quirk much credence. Information on conjoined twins emphasizes that even people who

are, by their very nature, always together and thus subject to virtually identical inputs,

will differ in their personalities. In actual cases of conjoined twins, it is absurd to suggest

that each twin is not her own person simply because she shares legs or most of a torso

with another person. (Other accounts of personal continuity agree: Parfit would consider

them separate so long as their psychologies are distinct, and Olson’s animalist account

would agree because such individuals have two brain-stems, although conjoined twins

with two cerebra and one brainstem would count as one human.)

The absurdity becomes particularly evident when we consider the situation of

conjoined twins if medicine were more advanced. Consider a pair of conjoined twins

who divide partway up the torso: the legs and lower organs in the torso are shared, but

their heads and brains are not conjoined to one another. Currently, it is impossible to

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separate such twins without killing at least one and the risk of killing both. Suppose that

this were not the case, however. Suppose that we could separate them and be assured that

both would survive the procedure, although of necessity they would not have complete

typical bodies afterwards. Having a complete body is clearly not a prerequisite for being

a person; the loss of a limb, or even all of one’s limbs indisputably does not rob one of

one’s status as a person. Thus, the fact that neither twin will have a complete body with

four limbs, etc., after they are separated cannot show that either twin is not a person.

Thus, the result of separating a pair of conjoined twins, joined at the torso, is two

independently-moving, independently-thinking people, who happen to have once shared

much of a body. Given that each of the resulting people has full normal cognitive

function and certainly enough of a body to qualify as a person, the fact that these two

once had legs and some organs in common seems a bizarre reason to claim that they are

not two distinct people. It is difficult to imagine any standard which could exclude both

twins as persons which is not grossly dehumanizing to people who are missing parts of

the body. There is no plausible reason to deny that conjoined twins are two distinct

persons if separated. Yet the separation of conjoined twins does not seem to be the sort

of thing which creates two people from one. Before the separation, as after, the

conjoined twins think independently of one another, move independently of one another

within the limitations of their bodies (having limitations on how one can move does not

make it the case that one is not a person, or else the paralyzed would not be persons,

which is clearly false). The fact that they are no longer sharing non-brain body parts

post-separation does not seem to be the right sort of thing to make two people where once

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there was one. Thus, conjoined twins with separate heads must be understood as two

distinct people, even if they are not separated. This shows that it is possible for two

people to share a single body.

If two people can share a single body, it seems arbitrary to draw the line at

sharing a skull, and claim that Irene and Helen cannot be two people even though they

share Jane’s skull with one another. Thus, cases in which hemispheres from the brains of

two people are transplanted into a single skull are best understood as cases of two persons

sharing a single skull. The reasoning that leads us to this conclusion follows from our

ordinary beliefs about persons. The hybrid view allows for this: each half-brain can

alone be sufficient for personal continuity, as real-life half-brain cases show. Happening

to share skull-space with another brain does not undermine any of the three criteria of the

hybrid view; thus, the hybrid view’s explanation of such a case is that it consists of two

distinct persons sharing a body.

The preceding discussion has assumed that the two hemispheres remain

independent in spite of sharing a single skull. What results if the two hemispheres are

joined in a way that allows them to function as a single brain? Suppose that Helen’s and

Irene’s hemispheres are transplanted into Jane’s skull, but connected to a healthy,

functional corpus callosum there, linking the two hemispheres. The corpus callosum will

allow the two hemispheres to ‘communicate’ with one another in the way that brain

hemispheres usually do. What is the result in such a case? Is Jane one person or two?

Our ordinary beliefs provide virtually no guidance in answering this question.

The possibility of two previously independent hemispheres coming to operate as one is

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far enough outside the realm of the ordinary that there seems to be no existing belief that

naturally extends to such cases, in contrast with the previous fusion case where our

practices concerning half-brain cases and conjoined twins combine to suggest a correct

response to the case. In short, it seems that neither our ordinary beliefs nor claims which

follow from our ordinary beliefs apply to such cases. Fusion is a gray area, a borderline

case. Given no clear answer to it, we can turn to our theory, the hybrid view, to supply

an answer to how to resolve the case.

The hybrid view does not provide much guidance here, either. Because a half-

brain is sufficient for both personhood and personal continuity, we know that these

conditions are met because an intact half-brain from each woman is present. So Jane is

continuous with both Helen and Irene. The real question is whether a healthy,

functioning corpus callosum is sufficient to make two persons into one. Fission cases

and real-world epilepsy surgery cases suggest that damaging or severing the corpus

callosum can effectively turn one person to two, but of course, this does not show that the

reverse is true. However, the issues with strict identity that arose in the discussion of

fission shed some light on the subject. As fission cases reveal, strict numerical identity

cannot be a necessary component of personal continuity. Fission shows that one person

can stand in a relationship of personal continuity with two people who exist concurrently.

This suggests that two people could stand in a relationship of personal continuity with

one person, as well: the fact that Helen is personally continuous with Jane and Irene is

personally continuous with Jane does not entail that Jane is two people instead of one. Of

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course, this does not settle the question, either – it merely shows that no problem arises if

Jane is to be understood as one person instead of two.

Because the hybrid view can accommodate both the possibility of two persons in

one body and the possibility of one person standing in a relationship of personal

continuity with two people, it will be able to accommodate either the claim that the two

hemispheres permanently remain two distinct persons, or the claim that the two persons

may eventually fuse into a single person. The hybrid view could accommodate this latter

possibility with emphasis on the role of the corpus callosum in uniting the psychology in

ordinary people. Severing the corpus callosum can cause two previously united

hemispheres to function as two distinct people, suggesting that although it is not essential

for the maintenance of psychological continuity, it has an integral role to play in

determining whether we are dealing with one person or two. The corpus callosum does

not bear the psychology itself, but it allows for the communication between hemispheres

that makes two hemispheres, capable of operating independently, act in concert as one

person. Given this role for the corpus callosum, the hybrid view could plausibly allow

for true fusion of two persons into one if their hemispheres, united by a corpus callosum

or artificial equivalent, communicate sufficiently to act in concert in the way that typical

brain hemispheres do. In this case, if the hemispheres communicate with one another and

act together as much as is typical for two brain hemispheres linked by a functioning

corpus callosum, it is reasonable to assert that true fusion has occurred: one person

results, who is nonetheless personally continuous with the donors of each hemisphere.

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Chapter 4: Objections

In this chapter, I discuss objections that the hybrid view may face. The first

section addresses a problem specific to the hybrid view, the question of whether physical

continuity can be required for our continuity, if psychological continuity is also required.

The next section deals with issues inherited from psychological continuity views,

primarily focused on the relationship of persons to human animals. In the final section, I

consider the broader question of whether the hybrid view really offers the best fit with

our existing beliefs without too many metaphysical tradeoffs.

1 The Unimportance of Physical Continuity

Proponents of both psychological and physical continuity views argue that it is

implausible to require physical continuity when one also grants importance to

psychological continuity. Derek Parfit argues that requiring physical continuity in

addition to psychological continuity is indefensible on the grounds that the existence of

particular bodies or body parts is not among the many qualities we value about ourselves

and others:

What we value, in ourselves and others, is not the continued existence of

the same particular brains and bodies. What we value are the various

relations between ourselves and others, whom and what we love, our

ambitions, achievements, commitments, emotions, memories, and several

other psychological features. Some of us would also want ourselves or

others to continue to have bodies that are very similar to our present

bodies. But this is not wanting the same particular bodies to continue to

exist. I believe that, if there will later be some person who will be R-

related [psychologically continuous] to me as I am now, it matters very

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little whether this person has my present brain and body… [I]t would not

matter if my brain was replaced with an exact duplicate.114

Parfit goes on to note that, although the maintenance of psychological continuity may

place limits on how different a body can be physically (for instance, a body of the same

gender may be required in order to allow for psychological continuity; or a very beautiful

person may require a physically-similar body), having a body which is numerically

identical is unimportant. Surviving in the usual way is not significantly better or worse

than having one’s body destroyed and having a perfect duplicate of oneself created, or

even having one’s psychology occur in a non-duplicate. Although he acknowledges that

people may fear a process which involves the destruction of their body and the creation

of a duplicate, he claims that this fear is not rational.115

Parfit’s claim, then, is that we place no value on physical continuity. We may

care about continuing to have certain physical features, but actually having the same

body, even the same brain, is unimportant. The only features that matter to us are

psychological; given that the relevant psychological features can be maintained without

physical continuity, physical continuity is not part of what matters to us in the business of

identity and survival. It is significant to note that Parfit’s claim here is not only about

what we ought to care about: his claim in the passage quoted above appears to be about

what in fact matters to us. As such, it is directly relevant to my argument, since my claim

is that the hybrid view is preferable to a view like Parfit’s on the grounds that the hybrid

114

Parfit (1986), 284-285.

115 Parfit (1986), 285.

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view is a better fit with our actual beliefs. If Parfit is correct that physical continuity is

not something that matters to us, my argument for the hybrid view is endangered.

If Parfit’s claim is that it is not rational for us to care about physical continuity as

well as psychological continuity, but not that we do not in fact care about physical

continuity, then his criticism is not applicable to the hybrid view, since it is meant to

reflect not how we ought to regard our own continuity through time, but how we actually

regard our own continuity through time. If, however, Parfit’s claim is that we do not in

fact care about physical continuity, I think it can be demonstrated that this claim is simply

false: we do, in fact, care about physical continuity, and do not consider psychological

continuity without physical continuity sufficient to make for our continued survival

through time. My reply to this objection is a simple modus tollens: if only psychological

continuity, and not physical continuity, matters, then facts about the mental states of

individuals we are not physically continuous with can make it such that we ought not to

care about our own deaths. Facts about the mental states of individuals we are not

physically continuous with cannot make it such that we ought not to care about our own

deaths. Therefore, it is not the case that only psychological continuity, and not physical

continuity, matters.

The first premise is uncontroversial; it merely rephrases Parfit’s claim on the

subject. Parfit clearly states that surviving through a duplicate is about as good as

surviving in the usual way.116

The proponent of a purely psychological view would reject

the second premise. However, I think we have independent, non-question-begging

116

Parfit (1986), 280.

142

reasons to accept the second premise. Consider again the case of Dan and Eric I

described in Section 2.2 of Chapter 2, when first discussing Parfit’s view. As I argued

there, it is simply not the case that Dan, having been hit by a bus, will not mind dying in

his last moments, if he is made aware of the fact that, across the globe, a stranger (Eric)

has received a head injury causing him to spontaneously developed a psychology exactly

like Dan’s at the time of the collision. Dan will not be comforted by this. Dan will find

his imminent demise no less objectionable for knowing that a perfect psychological

duplicate exists out there somewhere.

One might object that I am speaking here of what would in fact result from Dan’s

situation, when I should be speaking of what Dan ought to feel in this situation. The fact

that he would object to dying even though a psychological duplicate exists does not show

that he ought to object to dying given that there is a psychological duplicate. Parfit

would claim that this is just one of the many places where our actual beliefs are irrational:

Dan ought not to mind dying, given that a duplicate exists. I think that this is simply

false. As such, I reach something of an impasse at this objection: Parfit or a proponent of

his view would gladly reject my second premise, while I think it is true on the basis of

what we in fact care about. If we did think of ourselves in the way that Parfit thinks we

should, then my second premise would be false. But given what I take to be the facts

about how we regard our own existence through time, it is not the case that we ought not

to mind dying if a duplicate exists. Our own deaths are still very bad for us, whether a

psychological duplicate exists or not.

143

This very situation is illustrated in the film The Prestige, in which a stage

magician seems to make himself vanish and reappear; in fact, the ‘reappearing’

individual is a duplicate, and the original is dropped beneath the stage to drown in a tank

of water. No one watching the film would be puzzled at finding that the man drowning in

the tank of water is struggling to prevent his drowning, even though he knows a perfect

duplicate has been created and will carry on his life. It would be baffling if he didn’t

struggle to survive. The fact that this occurs as a plot element in a work of fiction serves

as an illustration of just how intuitive this response to duplication is: having a perfect

duplicate will not make us any less opposed to dying.

1.1 A Second Argument for the Unimportance of Physical Continuity

In his argument against a role for psychological continuity as a criterion of

identity, David Hershenov also raises concerns about the significance of physical

continuity if psychological continuity is considered relevant to personal identity, claiming

that such a view is “likely to collapse into it is just psychological continuity that

matters.”117

Hershenov’s criticism arises from concerns about very similar, but non-

identical, psychologies. His claim is that “[i]t seems arbitrary for a person to identify

himself with the one [continuous psychology] and not another closely related [continuous

psychology], possessing but a few more or less thoughts.”118

If a person is identified

with a specific sequence of psychological features, as a view calling for psychological

117

Hershenov (2004), 469.

118 Hershenov (2004), 470.

144

continuity suggests, Hershenov’s claim is that it is arbitrary for such a person to identify

himself with one particular continuous psychology rather than another which differs from

it only minutely, in the same way that it is arbitrary to distinguish between two masses of

water molecules that differ by only a molecule or two, claiming that this mass is the

cloud and that mass is not. If it is thus arbitrary to identify oneself with a particular

continuous psychology over a nearly-identical one, this suggests that insisting on

(physical) identity in addition to psychological continuity is unreasonable, since

psychological continuity can outlast any given physical entity.

Although strict identity and physical continuity are closely linked in matters of

personal identity, with lack of strict identity being one of the criticisms of views that

claim psychological continuity is sufficient for continued existence, the hybrid view’s

call for physical continuity, rather than strict identity, spares it from this objection. The

hybrid view, in spite of requiring physical continuity as well as psychological continuity,

does not require that an individual is identified with this specific sequence of

psychological states rather than that nearly identical one. Rather, it requires that the

individual is identified with the sequence of psychological states maintained by the

physical continuity of a given brain (which, like the psychology, like the cloud, may have

blurry edges where it is arbitrary to say whether some given particle is a part of it or not).

Whether the physical continuity in fact is responsible for the psychological continuity

determines whether the individual is identified with this or that psychology; as such,

distinguishing between them is not arbitrary.

145

Hershenov’s more general point may still be a concern, however: if psychological

continuity matters at all for personal continuity, does the importance of physical

continuity for our continued existence collapse, so that it turns out that only

psychological continuity matters? If psychological continuity is pitted against physical

continuity, it seems that psychological continuity will win out: in a situation where a

perfect psychological duplicate of me exists, and my current body, brainless, exists, the

perfect psychological duplicate seems a far better candidate for being me than the

brainless body, on the assumption that psychological continuity matters for continued

survival. In light of this, one might be concerned that physical continuity does not really

matter at all.

Our response to cases where there are two individuals bearing our psychology,

but only one is physically continuous, shows that physical continuity does matter to us

even if psychological continuity is relevant. This is illustrated by a case described in

Chapter 2, section 2.2. Claire enters a teleporter on earth. It scans her, and uses local

matter to create a perfect duplicate of her on Mars. On earth, she exits the teleporter

unharmed; it has not disintegrated her as we usually think a transmitting teleporter would

do. All that happened to Claire in the teleporter’s booth is that the exact microphysical

state of her body was scanned. We might plausibly think that the duplicate of Claire

created on Mars is Claire, if the duplicate on Mars is the only individual who is

psychologically continuous with Claire. But given the continued existence of Claire on

earth, the Martian duplicate’s claim on being Claire seems far more dubious. We might

even think of Claire on earth as the real Claire, and the one on Mars as a mere duplicate.

146

We are unlikely to accept that the duplicate on Mars is Claire when we have a competitor

who stands in a relationship of physical continuity to the original. This shows that even

if psychological continuity does matter to us – even if we would say that Claire ceased to

exist if the teleporter malfunctioned so that it destroyed her brain and created no duplicate

– physical continuity also matters to us. In a situation where psychological continuity

alone is pitted against psychological continuity in virtue of physical continuity, it

becomes obvious that psychological continuity caused by physical continuity is

preferable to psychological continuity alone.

2 What Are We?

Judith Jarvis Thomson claims that many accounts of personal identity encounter

difficulties when it comes to the related but distinct question of what we are. Olson terms

this the question of personal ontology, as opposed to personal continuity.119

Thomson

claims that psychological views of personal identity leave their proponents with no viable

explanation of our ontology, and considers this a weakness of psychological continuity

views that should not be ignored: “[I]f the identity criterion a philosopher offers us is

such that if the criterion were true, then it is obscure what people could possibly be, then

isn’t that a count against his or her criterion?”120

Thomson argues that, because any view

calling for psychological continuity cannot identify us with our bodies, there is no

plausible answer to the question of what we are. Olson raises similar concerns, claiming

119

Olson (2007), v.

120 Thomson (2008), 157.

147

that a view which calls for psychological continuity is incompatible with the claim that

we are animals, and that rejecting the claim that we are animals is a serious defect.121

The hybrid view does seem to be incompatible with Thomson’s claim that people

are their bodies, because per the hybrid view, we may outlast our bodies, and our bodies

may outlast us. In a brain swap, the body I now call ‘my body’ could be destroyed while

I lived on, my cerebrum safely transplanted into another body. It is also possible for my

body to outlast me, if my cerebrum is damaged or altered so that psychological continuity

is not maintained but the body remains alive (perhaps even still meeting the criteria for

personhood). In each of these scenarios, the individual and the body go out of existence

at different times from one another, meaning that it is not compatible with the hybrid

view to claim that the individual is her body, period. Thomson claims that only the view

that people are their bodies – a physical continuity view that gives no role to

psychological continuity – has a plausible answer to the ontological question of what we

are. 122

If she is correct, and acceptance of the hybrid view means there is no good

answer to the personal ontology question, the question of what we are, then as Thomson

asserts, that ought to be considered a strike against the hybrid view.

Olson raises the same concern, but focuses on contrasting the human animal with

other animals, noting that we do not consider psychological features relevant to the

continued existence of any other animal. His conclusion is somewhat stronger than

Thomson’s: his claim is that if psychological continuity plays a role in our continuity,

121

Olson (1997), 94-97.

122 Thomson (2008), 157.

148

then we are not human animals, but because we are human animals, it must be false that

psychological continuity plays a role in our continuity. Rather than merely protesting

that there is no good answer to the question of personal ontology, Olson’s claim is that

we are stuck with a particular answer to the question of personal ontology, and any view

incompatible with this answer must be false. It is obvious that the continuity conditions

of non-human animals are not determined by psychological features: a bear with its

forebrain removed is simply a brainless bear; it does not cease to be a bear for having lost

its forebrain. Olson argues that human animals should be understood in the same way:

the continuity criteria of human animals must not be determined by psychological

features any more than the continuity criteria of a bear or a cat would be.123

The

challenge for the hybrid view is to explain our relationship to human animals in a way

that is satisfactory without having to give up on the role of psychological continuity as a

required element of our continued existence. What can the hybrid view claim that we

are?

Thomson and Olson both acknowledge that proponents of a psychological

continuity view of personal identity do have one answer available to them, but that it is

not a very appealing one. If we are immaterial, then the question of what we are is

settled: we are immaterial entities of whatever sort (minds, egos, souls, etc.). This view

is not particularly attractive to most. If accepting a particular account of personal identity

requires claiming that we are mental substances, this is more likely to be seen as evidence

123

Olson (1997), 94-97.

149

that the account is false than reason to think that we are mental substances.124

As such, I

set this possibility aside. What else might we be?

The claim that we are persons seems well-suited to an account of personal

continuity calling for psychological continuity. Because persons are defined by their

psychological features, this response seems to fit well with any account of personal

continuity which calls for psychological continuity as a necessary component, as the

hybrid view does. However, claiming that we are persons does not fully settle the

question of what we are. Olson claims that this does not actually answer the question of

what we are, asserting that “the claim that we are [persons] tells us nothing about our

metaphysical nature.”125

More needs to be said about what a person is, and the

relationship of persons to human animals, or the personal ontology question remains

without a satisfactory answer. In the next sections, I consider several possible ways of

understanding us as persons.

2.1 ‘Person’ as a Functional Category

P.F. Snowdon, criticizing Locke’s approach to distinguishing persons from

animals, claims that if personhood is defined as it is by Locke, in terms of higher

cognitive functions (and my gesture at a definition of personhood is similar enough to

Locke’s that the same concern applies), ‘person’ is a functional category to which other

entities may belong. In the case of you and I, the entities which belong to that functional

124

Thomson (2008), 156; Olson (1997), 95.

125 Olson (2007), 8.

150

category are animals. Thus, Snowdon claims, the definition of a person does not actually

succeed at distinguishing persons from animals; it merely demonstrates that some

animals are persons, but does not tell us what a person really is.126

The hybrid view is unlike Locke’s view in that it calls for physical continuity in

addition to psychological continuity. This difference may mean that the hybrid view is

not subject to this difficulty for Locke’s view. Because the hybrid view calls for physical

continuity as well as psychological continuity, it may be feasible to answer the question

of what we are in exactly that way: perhaps we are animals which belong to the

functional category ‘person.’ We cannot be animals simpliciter per the hybrid view,

because an entity can continue to be an animal without psychological continuity. Could

specifying that we are animals which belong to the functional category ‘person’ in virtue

of their consciousness, capacity to reason and so forth?

Ultimately this approach will not succeed without tweaking our notions about the

continuity of animals, probably beyond acceptability. The problem once again arises

from the transplant intuition and cases of body-swapping. As has been established, the

hybrid view holds that when a portion of the brain, maintaining psychological continuity,

is transplanted into another body, the owner of the brain goes where the brain goes: a

body-swap occurs. To claim that we are animals occupying the functional category

‘person’ while allowing for body-swaps, we must say that the animal goes where the

portion of the brain responsible for psychological continuity goes. The typical arguments

about the continuity of animals reject this, identifying the continuity of an animal with

126

Snowdon (1990), 89-90.

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the brain stem rather than the cerebrum because the brain stem is responsible for

maintenance of the animal’s life functions. Thus, in a brain-transplant case where the

cerebrum, maintaining psychological continuity, is separated from the brain stem, the

animal stays put in the original body, but the person swaps bodies. If this is the correct

way to understand the case, the possibility of claiming that we are animals occupying the

functional category ‘person’ is ruled out.

To reconcile the hybrid view with the possibility that we are animals occupying a

given functional role, it would be necessary to identify animals with the part of the brain

responsible for maintaining psychological continuity, rather than the part of the brain

responsible for maintaining basic life functions. Unfortunately for this answer to the

question of what we are, this is implausible, given that our typical understanding of

animals allows that an animal can continue to exist when virtually any part of its brain

but the brain stem is removed. As Olson puts it, in removing the cerebrum from an

animal, the surgeons performing the procedure do not create an animal – the animal “was

there all along, first with a cerebrum and then without one.”127

As a vivid illustration,

consider cases of so-called ‘headless chickens’ which purportedly can survive for months

after the removal of most of the head because the brainstem remains intact128

: the

headless chicken is clearly still a chicken – an animal. It is implausible to claim that

human animals are different from other animals in this regard – that humans persist so

127

Olson (1997), 18.

128 Discussion of Mike the Headless Chicken in a neuroscience textbook, Lambert and Kinsley (2005), 83-

84, may lend credence to the reality of the case.

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long as their cerebrums operate in a particular way, while other animals persist so long as

their hindbrains operate in a particular way. Noting that human animals are persons first

is ineffective at justifying regarding them differently in this way, as it merely reiterates

the difference, rather than explaining it. One could claim that all animals are something

else first, and animals only second, with persistence conditions defined by the ‘something

else,’ but it is implausible to suppose that this is true of most animals. The human

animal’s relation to personhood does not seem to have analogs in other animals that do

not resemble persons at all.129

As such, it is not feasible for the hybrid view to claim that

we are animals which fit into a functional category due to the proper functioning of our

forebrains.

2.2 Persons Constituted by Human Animals

Identifying persons with human animals is not a viable option because a human

animal and its person can diverge, as in the case of a brain transplant. Persons are thus

not identical to human animals, but we do not want to say that they are immaterial. How

can the person and the human animal coexist, both material, yet remain distinct?

One approach is to claim that, although persons and humans are not identical to

one another, they can occupy the same space and be made up of the same matter. If it is

possible for masses of matter – lumps of clay, aggregates of Legos, masses of atoms – to

simultaneously constitute two non-identical objects, then a person and a human animal

could share the same matter – coincide materially – without being identical, so that both

129

Olson (1997), 110.

153

person and human animal are material but the two remain distinct. On this theory, each

person coincides materially with a single animal in ordinary cases, but in the hypothetical

cases of brain transplants as so forth, a single person could coincide with two different

animals at two different times, with a brief period during which the person coincides with

no animal, only a part of an animal, a detached cerebrum. The notion is that by being

composed of the same matter, but non-identical, it is possible for the person and the

animal to differ in their properties while coinciding materially. This sort of relationship

is classically illustrated by a lump of clay and a statue.130

Although the statue is made up

of the very same material as the lump of clay, with no additional parts, it seems that the

statue can cease to exist while the lump of clay continues to exist, as would occur if the

statue were crushed back into a shapeless blob of clay. If the statue and the clay differ in

their modal properties, as they seem to, then per Leibniz’s Law, they cannot be

identical.131

So it seems that the statue is constituted by the lump of clay, materially

coinciding with it but distinct from it, and in the same way, the idea here is that the

person is constituted132

by the human animal, materially coinciding with it but distinct

from it.133

130

Gibbard (1975).

131 Bennett (2004), 339.

132 In The Human Animal, Olson appears to make a distinction between material coincidence and

constitution (101-102), but more recently characterizes constitutionalism as “the view that qualitatively

different things can coincide materially,” (Olson (2007), 50), although he also notes there that material

coincidence is an equivalence relation while constitution is not (50-51). I focus my discussion on

154

Under this interpretation, it may even be possible to assert that a person is a

human animal, in a sense. Shoemaker discusses the possibility that when we say that a

person is an animal, we are speaking accurately, but ‘is’ here refers not to identity, but

constitution.134

One might think that a person is an animal in the same sense that the

statue is a lump of clay. They are made up of the same matter, but are distinct because of

their different qualities: the lump of clay would continue to exist while the statue would

cease to exist if it were crushed or shaped into a new form. Because the clay and the

statue have different persistence conditions, with the statue able to go out of existence

while the clay remains, this suggests that the statue and the clay are distinct, in spite of

the statue being made up of the clay, having no part which is not part of the clay, and so

on.135

The person and the animal are related in the same way: the person has no part

which is not also part of the animal, but because the person and the animal, like the statue

and the clay, have different persistence conditions, they can rightfully be understood as

distinct. Due to the complete coincidence of person and animal, it is easy to mistake the

relationship between them as one of identity, but it is in fact a relationship of

constitution.136

Thus, if this constitution view is correct, one may not be mistaken in

constitutionalism specifically, as it appears to be the strongest version of a material coincidence view if

there are in fact others.

133 Olson (2007), 48-51.

134 Shoemaker notes that this approach is prima facie counterintuitive, but argues that it is one of the least

objectionable of several counterintuitive alternatives (S. Shoemaker (1984), 114).

135 S. Shoemaker (1984), 113.

136 Olson (1997), 96.

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asserting that a person is a human animal – only mistaken in thinking that ‘is’ is used in

the sense of identity.

Likened to the relationship of a statue and the lump of clay that makes it up,

constitutionalism seems like a promising way of characterizing the relationship between

human animals and persons, making it possible to answer the personal ontology question

by identifying us as persons without having to claim that persons and human animals are

identical. Of course, constitutionalism is not without its potential difficulties, and in

addition to the issues associated with constitutionalism in general, a constitutionalist

explanation of the relationship of persons and human animals leads to some problems of

its own.

One major issue for constitutionalism in general targets its central claim, the idea

that two distinct objects can simultaneously be composed of all and only the same matter.

The grounding problem is the problem of explaining how two objects could differ in their

properties if they are made up of the same matter, and are therefore materially identical.

Critics of constitutionalism claim that the material identity of the two objects means that

there is nothing to ground the differences that the constitutionalist claims the objects

have. 137

The most important purported difference in properties (for my purposes and in

the discussion of the grounding problem in general) is the difference in persistence

conditions: the lump of clay can outlast the statue; the human animal can outlast the

person; the person can outlast the human animal. The person and the animal are

137

Bennett introduces this name for the problem in Bennett (2004). The problem is also discussed in Olson

(2001), Sider (2008), Sosa (1987), and Zimmerman (1995), among others.

156

qualitatively identical in virtue of being made up of the same stuff put together the same

way, yet the person can be destroyed by the application of forces which do not destroy

the animal. Destroying the cerebrum but leaving life-maintaining parts of the brain

undisturbed kills the person but not the animal, and removing the cerebrum and

destroying the rest of the body kills the animal but not the person. For constitutionalism

to offer a viable answer to the personal ontology question, it must be explained how the

person and the animal, materially identical, can have different persistence conditions.138

One might attempt to argue that the difference in persistence conditions is not the

only difference that exists between a person and its human animal, noting that persons

have many qualities, psychological and otherwise, which mere animals lack, such as the

ability to write philosophy papers, or wish it were the weekend. Because persons and

animals thus differ in ways other than their persistence conditions, one might argue that

these differences ground the differences in persistence conditions. This reply is likely

ineffective, as it merely shifts the grounding problem to the question of how persons and

animals differ in these qualities instead, from the question of how persons and animals

differ in their persistence conditions.139

The human animal is qualitatively identical to

the brain of the person it coincides with, so if the person can write philosophy papers and

wish it were the weekend, there is no good reason to claim that the human animal cannot

138

Olson (1997), 98.

139 deRosset argues that this shift may help the constitutionalist’s case, claiming that the need for

explanation of non-modal differences between materially coincident objects is distinct from the grounding

problem, but acknowledges that the need for explanation remains. (deRosset (2011), 179-183).

157

also do these things. The human animal’s brain is doing the very same things that the

person’s brain does when the person engages in these activities. There is no material

difference to ground the claim that the person is capable of writing philosophy papers and

wishing for the weekend but the animal is not.140

Here, the grounding problem leads into a specific problem for constitutionalism

and personal identity: the problem of too many thinkers. If I think, and the animal I am

constituted by thinks, but I am not identical to that animal, it seems there are too many

thinkers in the picture: for each thinking person, there is also a thinking animal. Without

reason to say that the human animal does not think when the person does, we seem to be

stuck with two thinkers, one person and one animal, where we should only have one.141

Karen Bennett identifies three ways that a constitutionalist might attempt to

resolve the grounding problem. The constitutionalist may claim that the differing

properties of coincident objects are grounded in the other properties of the objects. The

constitutionalist may claim that the differing properties of coincident objects are

grounded not in any features of the objects themselves, but in our conventions

surrounding them. Or, finally, the constitutionalist might claim that the differences are

brute facts. Bennett argues that the latter is the most promising, although she does not

endorse it.

The failure of this first approach – claiming that the differing properties of

coincident objects are grounded in the properties of the objects themselves – is fairly

140

Olson (1997), 100; Bennett (2004), 340-341.

141 Olson (2007), 35-36.

158

obvious, and the source of grounding concerns to begin with. The person and the human

animal do not differ materially or relationally from one another, and as such, there is no

way to claim that the person has properties the human animal does not have, since on this

approach, those properties would have to be grounded in the properties that the human

animal also has.142

Louis deRosset argues that identity claims could be used to ground

the modal differences of two materially coinciding objects – it is true of the person that it

is identical to the person, but false of the animal that it is identical to the person, and thus

there is a non-modal difference between the two – but it is not clear that this approach

avoids circularity, in spite of deRosset’s assertion to the contrary.143

The next possibility is that the differing properties of persons and human animals

might arise not from the material properties of the matter that person and human animal

share, but from human conventions. Bennett does not take issue with the notion that our

conventions can determine what properties an object has, but rejects this approach as a

way for the constitutionalist to resolve the grounding problem. If our conventions can

cause materially coincident objects to have different properties, then either the coinciding

objects already exist, distinct from one another, when we apply our conventions to them,

or we cause the materially coinciding objects to become distinct from one another when

we apply our conventions to them. The former is problematic, as it would require us to

claim that the materially coinciding objects were already distinct from one another in

spite of differing in no way, since, on this view, it is our conventions that they differ in,

142

Bennett (2004), 342-344.

143 deRosset (2011), 183-188.

159

and we are talking about the possibility that they differ before our conventions enter the

picture. The latter, Bennett argues, is not as outlandish as it sounds. It does not require

anything like the idea that we summon objects into existence. But this approach fails

nonetheless. Attempts to formulate how we might cause materially coincident objects to

become distinct by applying our conventions and concepts do not succeed, because they

are not conceptually true. Merely being true, as Bennett notes, is not enough; without

conceptual truth in the picture, this response collapses into the first, unsuccessful

response.144

The remaining option Bennett considers is the view that there isn’t anything that

grounds the difference in properties of materially coincident objects, that the ways in

which a person and a human animal, or a lump of clay and a statue differ, are merely

brute facts, not grounded in anything else. As Bennett notes, this sort of move is likely to

be regarded as suspect, or as confirmation that materially coincident objects cannot differ

in their properties after all. In spite of this, Bennett argues that it may be possible to

justify this interpretation. Her proposal involves the claim that in any spatiotemporal

region that contains an object, there is a plenitude of objects, instantiating every

combination of modal properties for that object. On this view, there is no need to justify

why these objects – a person and a human animal, or a statue and a lump of clay –

materially coincide, because those objects are merely a few of the many objects, differing

only modally, that occupy that region: “because all of the complete modal profiles

possible in a given spatio-temporal location are instantiated there, there is no contrast to

144

Bennett (2004), 345-351.

160

be drawn between those that are instantiated and those that are not.”145

From there, one

might then argue that the connection between an object and its modal profile – whether it

has the properties it has necessarily or contingently – is primitive. This approach

removes the mystery of how modal differences could be primitive by putting all the

modal options, both the ones we are interested in, like the modal profile of the person and

the human animal, and the ones we are not interested in, on par with one another,

meaning there is no need to explain what makes the person and the human animal so

special. They aren’t so special, metaphysically; they do not differ from the multitude of

other modal profiles in any way beyond that they are the modal profiles we pay attention

to.146

Bennett does not endorse this view, and notes many places where it would have to

be developed further to be a viable option for the constitutionalist. But if she is right that

this plenitude approach is the only way the grounding problem can potentially be

addressed, the constitutionalist would need to use this approach to explain the

relationship of persons and human animals: persons and human animals, identified by

their continuity conditions, are merely two among many objects that coincide materially,

and what makes them stand out is just that they are the objects we are interested in among

all those many.

Accepting this way of avoiding the grounding problem will have implications on

the way the other major issue for the constitutionalist about persons and human animals,

the too-many-thinkers problem. The problem, when initially posed, was that there was

145

Bennett (2004), 355.

146 Bennett (2004), 352-359.

161

one thinker too many: a thinking person, and a thinking animal. But if the

constitutionalist takes the plenitude approach, as Bennett argues she must, then we have a

lot more than one thinker too many. By multiplying the number of materially coincident

objects, the plenitude approach also multiplies the number of extra thinkers. Fortunately

for the constitutionalist, a plausible way of resolving the too-many-thinkers problem

works equally well regardless of how many more thinkers we have than we need.

To avoid the problem of too-many-thinkers, one could claim that overlapping

entities, like a person and the human animal that person coincides with (and all the other

objects that exist per the plenitude view), are counted as one in any ordinary context, in

the same way that David Lewis says we might count 1000 overlapping candidates for

being ‘the cat on the mat,’ differing only in whether they include individual hairs, as one

cat. The 1000 cat-candidates are not identical to one another, and each meets the criteria

for being a cat on its own, but when counting how many cats are on the mat, we count

one.147

We might count thinkers in the same way: the person and the human animal (and

all the rest) are not numerically identical to one another, just as two cat-candidates which

differ by a hair or two are not numerically identical to one another, but this does not mean

that we should count two (or two million) thinkers when thinking occurs, any more than

we should count two cats.

Olson argues that this approach is unappealing on the grounds that this linguistic

hypothesis, which claims we count non-overlapping thinkers rather than thinkers period,

seems false, claiming this hypothesis “does little to make it easier to believe that there are

147

Lewis (1999), 177-179.

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two numerically different philosophers sitting there and reading this now.”148

I find

Lewis’s proposal more palatable than Olson does. Claiming it seems false that there are

multiple numerically distinct thinkers writing this sentence sounds right, but relies on the

assumption, which Lewis’s proposal challenges, that we are thinking in terms of

numerical identity when we count the number of thinkers here. If it is true that we count

these materially coincident entities, the person and the human animal (and the rest), as

one when we count thinkers, then of course it seems false that there are multiple different

thinkers writing this sentence; if this proposal is correct, there aren’t, per the way we

count thinkers. The claim seems false only on the assumption that we typically count

thinkers on the basis of numerical identity; it is not clear to me that this must be the case.

As such, Lewis’s many-but-almost-one proposal may provide a way to sidestep the issue

of too many thinkers. It will not satisfy opponents like Olson, but the concerns raised

against this reply are not decisive.

Between Bennett’s suggestion for a way the constitutionalist might avoid the

grounding problem, and Lewis’s many-but-almost-one approach to the problem of too

many thinkers, the view that we are persons, where persons are materially coincident

with, but non-identical to, human animals, may serve as an answer to Thomson’s

personal ontology question. Unanswered questions remain, to be sure, but

constitutionalism remains a potentially viable answer to the question of what we are.

2.3 Persons as Cerebrums

148

Olson (2007), 36.

163

According to the hybrid view, like any other view calling for psychological

continuity, we cannot be identical to human animals. Explaining the relationship that

exists between us and human animals thus seems to be a major difficulty, unless one is

willing to commit to the rejection of physicalism and claim that persons are immaterial.

But the hybrid view may have an advantage over views that call for psychological

continuity alone, because per the hybrid view, identity of a physical part is a necessary

condition for personal continuity. Because the hybrid view requires psychological

continuity in virtue of physical continuity, and physical continuity requires identity of a

material part, the hybrid view can identify us with the parts of human animals responsible

for maintaining psychological continuity: our brains, or rather, the portions of the brain

responsible for maintaining psychological continuity,149

the cerebrum.150

Identifying us with our cerebrums provides a way to avoid many of the

difficulties associated with explaining the relationship between us and whole human

animals. If we are our cerebrums, the transplant intuition is readily explained, because

the cerebrum does go from one body to another, but no human animal does. The

destruction of a cerebrum ensures the destruction of the person whose cerebrum it was,

while destruction of a human animal less its cerebrum does not ensure the destruction of

the person whose body it was. In short, the continuity conditions of cerebrums are much

149

Though he speaks in terms of identity of consciousness, rather than psychological continuity,

McMahan’s Embodied Mind view (McMahan (2002), 66-69) is very similar to what I argue for here,

although my view differs from his somewhat in borderline cases of personhood.

150For simplicity’s sake, I’ll speak just of cerebrums here, but as before, if it turns out that other portions of

the brain are also involved in the maintenance of psychological continuity, they would also be included.

164

more like the continuity conditions I have identified as personal continuity conditions

than the continuity conditions of whole human animals are. There is no need to worry

about committing to non-physicalism if we are our cerebrums, since cerebrums are

plainly material entities. The view that we are our cerebrums seems to be a good fit for

the hybrid view.

Is it plausible to identify us with our cerebrums? Some fairly obvious concerns

arise. For example, if I am a cerebrum, then it is false, strictly speaking, that I have

hands, that I am 5’6” tall, etc. – these are traits that my body has, but not traits that I

have, if I am a cerebrum. If I am a cerebrum, then I do have a height and a weight – but

it is the height and weight of my body, including the cerebrum, not the height and weight

of my cerebrum alone, which we mean when we think of ourselves as having such-and-

such a height or weight. If I am my cerebrum, then no one has ever seen me, given that I

have never had my skull opened.151

These concerns can potentially be dismissed by claiming that, although I might

say that I am 5’6”, what I really mean is that my body is 5’6”, the same way I might give

directions to my house by saying “I’m the grey one on the corner,” or complain that

someone almost hit me in traffic today, when really, they almost hit my car. These

examples illustrate that we sometimes use personal pronouns to refer to objects we are

clearly distinct from. Is it plausible that this is what is going on when I say that I am

5’6”? Probably not. If pressed, I will readily admit that when I say, “I’m the grey one on

the corner,” I really mean, “my house is the grey one on the corner,” that when I say

151

Olson (2007), 76.

165

“someone nearly hit me in traffic today,” I really mean “someone nearly hit my car in

traffic today.” These are figures of speech, and anyone who uses such a figure of speech

will not hesitate to admit, when pressed, that they are not speaking literally. The same is

not true of claims I might make about my body. If someone asks if I am really 5’6”, I

won’t readily admit, “no, really my body is 5’6”. I’m about 4” tall (or however tall a

cerebrum is).” This is the sort of claim that no ordinary person, and probably very few

philosophers, could ever make seriously.

A somewhat more sophisticated variant of this approach might do the trick,

however. One might claim that, although referring to my house or my car as ‘me’ is a

mere figure of speech, one we abandon when questioned, referring to my body as me,

even if I am not identical to it, is more than that. It may be that, by linguistic convention,

when we speak of ourselves as having height, weight, when we think of whether we have

ever seen people we know, we refer to our bodies, even if we are cerebrums. When I say

that I am 5’6”, this is true, although it is false that my cerebrum is 5’6”, but by linguistic

convention, saying I am 5’6” means my body is 5’6”, not that the object I am strictly

identical to, my cerebrum, is 5’6”.

Olson claims this reply is implausible: “When we say that Haroun is six feet tall,

we don’t seem to mean merely that he relates in a certain way to something or other that

has the property of being six feet tall. We seem to mean that Haroun himself has that

property.” 152

This concern doesn’t do much to undermine the plausibility of the reply, in

my view: consider that, for much of human existence, people have identified themselves

152

Olson (2007), 77.

166

with something immaterial, the soul. Yet the idea that people have heights, weights, can

be seen by others and so forth, is not new. It is not a product of moving away from the

notion that we are souls. This suggests that even when people accept a view according to

which we are not identical to our bodies, we still speak of the properties our bodies have

as though they are properties that we have. People who identify themselves with souls

won’t counter a request for their height by saying, “Well, as an immaterial entity, I have

no height. But my body is six feet tall, if that’s what you were asking.” As such, I think

it is not at all implausible to suppose that we might speak as though the properties of our

bodies are properties of ourselves even if we do not identify ourselves with our bodies.

We have fairly good reasons to think that linguistic conventions may exist according to

which we speak of the properties of our bodies as our own properties.

There are other possible peculiarities resulting from this view. For instance, one

might be concerned that, if we are functioning cerebrums, and we are persons (since

personhood is defined in terms of cognitive capabilities), this means that normal, healthy

human animals literally, physically contain persons, which sounds odd, because unlike

‘cerebrum,’ ‘person’ is not a name for a part of the body. I agree that this sounds odd,

but do not think it presents a serious problem for the view. In defending animalism,

Olson argued that, although it sounds strange to say, “my body wrote a letter to your

body,” we should not take that strangeness as evidence that animalism is false. It sounds

strange, he claims, because using that language, accurate though it is per animalism, has a

misleading conversational implicature. I borrow Olson’s claim to use in the opposite

direction. The fact that it sounds strange to say that part of my body is a person should

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not be taken as evidence that it is false, for roughly the same reasons: when we speak of

the human animal as a body, or its parts, we typically do so to draw attention to what

Olson refers to as ““brute” physical features” rather than mental features. 153

When

considering the human animal in terms of its parts, we do not typically invoke

personhood because when speaking of the human animal in terms of its parts, we are

focused on the physical rather than the mental.

So far, identifying us with cerebrums looks fairly promising for the hybrid view.

There is one potentially more serious concern, however: although the continuity

conditions of a cerebrum are much more like our continuity conditions than the

continuity conditions of a human animal are, the cerebrum’s continuity conditions are not

identical to the conditions I have identified as our continuity conditions. Specifically,

identifying us with cerebrums does not guarantee psychological continuity in virtue of

physical continuity. Physical continuity is guaranteed by identity of the cerebrum, but a

cerebrum can continue to exist when it is no longer capable of meeting the conditions for

psychological continuity, as in the case of serious brain damage. A badly damaged

cerebrum may still exist – still properly be called a cerebrum – when it is no longer

capable of housing a person, no longer capable of the kinds of cognition required for

personhood. So the continuity conditions of a cerebrum are not identical to the continuity

conditions I have identified as our continuity conditions.

McMahan’s version of this view suggests a fix: rather than identifying us with

cerebrums, period, we need to identify ourselves with cerebrums operating in a certain

153

Olson (1997), 101.

168

way. Mere physical continuity of the cerebrum is not enough; continuity of function of

the cerebrum is also required if the cerebrum is going to be able to maintain

psychological continuity, as the hybrid view requires. The cerebrum must continue to

function in such a way that psychological continuity is maintained.154

So the view, then,

is that we are cerebrums operating in such a way that they maintain psychological

continuity.155

The continuity condition of a cerebrum operating in this way aligns with

the continuity conditions I have identified as ours, so as a response to the personal

ontology question, the claim that we are cerebrums may be the best bet for the hybrid

view.

3 Fit with Beliefs versus Metaphysical Tradeoffs

Another sort of objection might be raised, not specifically against the hybrid view,

but against my claim that the hybrid view provides the best balance of fit with our

existing beliefs and metaphysical coherence. As the previous sections of this chapter

have shown, the hybrid view is not without its metaphysical difficulties; although I have

attempted to offer solutions to the problems that may arise from it, it could be argued that

154

McMahan (2002), 67-68.

155 Talk of cerebrums functioning in such-and-such a way might bring to mind Snowdon’s concern about

identifying ‘person’ as a functional category to which a human animal can belong (section 2.1). That

problem is avoided here, because unlike the situation between persons and human animals, showing that

some cerebrums are person-maintaining is precisely what we want to do. Identifying ourselves with

cerebrums working in a certain way aligns our continuity conditions, whereas it does not when we identify

ourselves with human animals working in a certain way.

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another view offers a better balance of fit and metaphysical coherence. For instance, it is

plausible to interpret Parfit’s position as one which holds that the metaphysical

advantages of a psychological continuity view are considerable enough that they

outweigh the counterintuitive nature of some results of his view.

It is difficult to defend a claim of this sort, as the very framework the question is

built on is open to disagreement: what makes one balance of fit with beliefs and

metaphysical coherence better than another? Many philosophers would happily abandon

fit with beliefs altogether and put their stock in whichever view they find most

metaphysically plausible, regardless of how poorly it fits our understanding of ourselves

and others. At the other extreme, one could disregard metaphysical coherence entirely

and say that fit with existing beliefs is all that matters, even when existing beliefs

contradict one another (admittedly, it is unlikely that anyone who considers herself to be

a philosopher would take this approach). There is, of course, a full range of options in

between these two extremes. So if the hybrid view has such-and-such balance of fit and

metaphysical merit, and other views have different balances of fit and metaphysical

merit, on what grounds can I claim that the hybrid view’s balance is best?

I think that the best balance of fit with belief to metaphysical merit is one which

doesn’t force us to abandon anything important, deeply held, on either side. If a view

requires us to accept something that is strongly counterintuitive, deeply opposed to what

we would ordinarily believe about ourselves, then that is a significant strike against that

view as the correct answer to the question I address here. But it goes both ways: if fitting

with our beliefs requires acceptance of a view that cannot be understood as

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metaphysically coherent, then that is a major strike against that view, too. My claim,

then, is that the hybrid view succeeds on both fronts: the elements of our ordinary beliefs

about ourselves and our continuity which we are required to give up in order to accept the

hybrid view are minor, and the metaphysical problems the hybrid view faces are not

insurmountable. The same cannot be said of the other major contenders.

There are multiple places where the hybrid view calls for departure from what we

might ordinarily believe about ourselves and our continued existence. The hybrid view

requires us to reject the possibility of teleportation as a means of travel; it requires us to

say that the torture of our own body, if the brain has undergone certain types of changes

beforehand, is not something we should feel prudential concern about; and it requires us

to say that we ourselves could, upon learning certain facts about our physical histories,

learn that we are not in fact the people we sincerely believe we are. I have argued that

each of these seeming departures from our ordinary beliefs becomes plausible when

considered in a more-than-cursory way. One does not have to be a philosopher to

conclude, for instance, when thinking seriously about the mechanism by which

teleportation occurs, that it kills you, since it involves vaporizing your body. So although

there are some ways in which the hybrid view seems not to fit with our ordinary beliefs

about ourselves, the beliefs that must be given up to accept the hybrid view are ones

which we are not too attached to, ones which become less plausible when we press them.

Thus, the hybrid view does a good job of fitting with extant beliefs.

Acceptance of the hybrid view does require one to contend with some potentially

serious objections. The objections discussed in the rest of this chapter have a common

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thread: the relationship of us, persons, and human animals. The hybrid view rules out the

possibility of identifying us with human animals, and explaining our relationship to

human animals if we are not identical to human animals faces serious difficulties, as the

objections discussed here reveal. I do not consider the problems of explaining this

relationship so substantial that they mean the hybrid view must be rejected, though others

may disagree with my assessment, claiming that other views have a better fit with beliefs

vs. metaphysical cost ratio. I maintain that incorporating both physical and psychological

continuity is crucial to explaining the way we understand our own existence through

time, since it appears to be the only way to avoid the serious breaks with our ordinary

beliefs that result from calling for only psychological continuity or only physical

continuity, and if doing so means identifying us with persons, as it may, then the

metaphysical costs of explaining how we can be persons rather than human animals is not

too high a price to pay.

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Chapter 5: Further Implications

In this chapter, I consider the impact that acceptance of the hybrid view may have

beyond the issue of personal identity. In the first section, I consider the metaphysical

implications of the hybrid view, arguing that the hybrid view does not require

cumbersome metaphysical commitments. In the second section, I discuss the ethical

implications of accepting the hybrid view, with particular emphasis on the hybrid view’s

implications for moral responsibility.

1 Metaphysical Implications

Because questions of personal identity are closely linked to other metaphysical

questions, the compatibility of a given account of personal identity with various

responses to these other questions impacts the view’s plausibility. The hybrid view is

relatively free of metaphysical commitments beyond the matter of personal identity,

allowing those committed to particular replies to these other questions to consider the

hybrid view a viable approach to personal identity.

1.1 Persistence

Because both topics deal with the persistence of objects through time, personal

identity is closely linked to persistence in metaphysics. In describing the four-

dimensionalist picture at the beginning of his Four Dimensionalism, Ted Sider uses the

example of a person to illustrate the idea of four-dimensionalism, merely noting that all

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other objects that persist through time are regarded in the same way.156

The hybrid view

of personal continuity clearly does not apply to objects like cars, trees, books, or cats,

because the identity of these sorts of objects through time plainly does not involve a

psychological component. It might seem that the hybrid view is at odds with the question

of persistence, then: the hybrid view is an account of how we exist through time, but it is

not an account of how any other sort of object persists through time. Does acceptance of

the hybrid view, singling us out among as different from other things, entail unacceptable

metaphysical commitments with regard to persistence through time? I argue that it does

not. The hybrid view is compatible with a three-dimensional, endurantist picture of the

way objects persist through time, or a four-dimensional picture of the way objects persist

through time. Acceptance of the hybrid view need not be contingent upon one’s

preferred account of the persistence of objects in general.

1.1.1 The Hybrid View and Endurantism

On the endurantist or three-dimensional picture of persistence, an object exists

completely at a time, rather than being extended through time. My desk is entirely

present in this moment; it does not have other parts that exist at other points in time. It

exists through time by being wholly present at a series of moments through time –

enduring through time. It is not extended through time with temporal parts that exist

through time – hence ‘three-dimensional’ as opposed to four-dimensional. Applied to

ourselves, this would mean that we exist completely in each moment of our existence. I

156

Sider (2001), 1.

174

exist completely at this moment on the endurantist picture; it is not the case that I have

some parts in the past and some in the future. The endurantist claim is that all of me is

right here in the present.

Trenton Merricks argues that any account of personal identity which calls for

psychological continuity is incompatible with endurantism. His claim is certainly

applicable to the hybrid view: he groups accounts of personal identity which require that

psychological continuity is caused by physical continuity with other accounts that do not

require physical continuity.157

Merricks argues this point by sketching out a picture of

how the psychological continuity relation might look in an endurantist picture, then

claims that this understanding of psychological continuity fails as an analysis of personal

identity. According to endurantism, he claims, “an instance of personal identity over

time just is an instance of a person’s existing wholly present at one time, a person’s

existing wholly present at another time, and the person who exist at the first time’s being

the same as – identical with – the person existing at the second.”158

The relation that

exists between this person and one time and themselves at another time is a relationship

of numerical identity, but psychological continuity is not a relationship of numerical

identity, even if it is stipulated that no branching has occurred, because numerical identity

is a relationship that exists between objects that do not possess psychological features of

any kind, like rocks. Merricks’s charge is that the endurantist must understand personal

identity in terms of numerical identity – a person existing at one time being identical to a

157

Merricks (1999), 984.

158 Merricks (1999), 986.

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person existing at another time – and psychological continuity, however it is understood,

is not a relationship of numerical identity, and therefore cannot be the relationship that

makes for personal identity.159

Merricks’s claim may have less impact on the hybrid view than it does on

exclusively psychological views, since strict numerical identity does have a role to play

in existence through time per the hybrid view. The claim that strict numerical identity of

human animals is required for personal continuity is incompatible with the hybrid view,

but the hybrid view’s requirement of physical continuity means that the numerical

identity of the cerebrum is a component of personal continuity. This does not allow the

hybrid view to avoid Merricks’s concern entirely, since numerical identity of the

cerebrum is not sufficient for personal continuity per the hybrid view. If the cerebrum

has changed such that psychological continuity is not maintained, personal continuity is

not maintained. So what the hybrid view calls for seems to be not less that numerical

identity, but more: numerical identity of the cerebrum such that psychological continuity

has been maintained. By combining this and the fact that the hybrid view is meant to

track what matters to us, even if that turns out not to be strict numerical identity, there

may be a way for the hybrid view to avoid this concern altogether. The endurantist could

think of personal identity as a cerebrum existing wholly at one time, a cerebrum existing

wholly at another time, and those two cerebrums being numerically identical, which is

compatible with the hybrid view so far; the stipulation is that the relation of personal

identity is thus not the one we care about. Personal identity, thus understood, plus

159

Merricks (1999), 985-989.

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psychological continuity in virtue of physical continuity, is what we care about. Because

numerical identity underlies personal continuity, the hybrid view is compatible with the

endurantist picture Merricks argues for, and the fact that the hybrid view does not claim

that all instances of personal identity thus understood are cases of personal continuity is

not a problem, since the hybrid view does not rely on the assumption that the relation it is

tracking is one of identity.

1.1.2 The Hybrid View and Perdurantism

Although Merricks’s intent in arguing that a psychological continuity view of

personal identity is incompatible with endurantism is not to show that we ought to accept

perdurantism instead, it does bring to light the way that psychological continuity accounts

of personal continuity fit well with the perdurantist picture. If perdurantism is correct,

then any object that exists through time, person or not, does not have numerically

identical parts existing at different times. My desk this morning and my desk now are

not, strictly speaking, numerically identical to one another in the perdurantist’s view. My

desk this morning and my desk now are the same desk in virtue of both being temporal

parts of the same four-dimensional object, but a different part existed this morning than

exists now. The temporal parts of an object that exist at two different times are not

numerically identical, any more than my left hand is numerically identical to my right

hand: they are both parts of the same thing, but they are not numerical identity, and the

fact that they are not numerically identical in no way undermines the claim that they are

parts of the same thing. The situation is no different for us. The part of me that existed

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this morning is not numerically identical to me now, because me now is a different

temporal part, but both are parts of the same four-dimensional object that is me existing

through time.

The hybrid view can be understood by the perdurantist as a view according to

which persons are temporally extended objects, and what makes it the case that two

temporal parts of a person belong to the same person are the continuity conditions

identified by the hybrid view. What makes it the case that me-this-morning is a part of

the same temporally extended object as me-now is the fact that me-this-morning and me-

now stand in a relationship of psychological continuity in virtue of physical continuity.

Me-this-morning and me-now are not numerically identical: me-this-morning was

primarily concerned with the acquisition of crepes for breakfast, while me-now is focused

on temporal parts, for example. But it is no surprise that me-this-morning and me-now

are not numerically identical; in the perdurantist’s view, this is old news, a result of the

perdurantist picture as a whole, rather than a result of the hybrid view. Concerns like

Merricks raised for this sort of view and endurantism, arising from the fact that

psychological continuity is not a relationship of numerical identity, will never get off the

ground if perdurantism is correct. It is a part of the perdurantist’s view, before personal

identity is even brought up, that the parts of something that exist at two different times

are not numerically identical. Because of this, identity concerns provide no stumbling

block for the hybrid view and perdurantism.

Perdurantism also provides alternative answers to the objections discussed in the

previous chapter. If objects have temporal parts, this opens the door to another possible

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answer to the question of personal ontology. If perdurantism is correct, we can be

identified with the temporally extended objects, spacetime worms, made up of temporal

parts united by their psychological continuity in virtue of physical continuity with one

another. The temporal parts view is very flexible, and can readily accommodate the

specifics of the hybrid view.160

It is compatible with perdurantism to claim that the

reason a perfect physical duplicate does not stand in a relationship of personal continuity

with the original is because the common psychology is not enough to link the four-

dimensional object that is the original to the four-dimensional object that is the duplicate:

the two psychologies, though identical, do not add up to a single spacetime worm that we

counts as a single person. Because most proponents of perdurantism accept unrestricted

composition, the view that any group of objects, including temporal parts, has a sum,161

the perdurantist can claim that there is an object consisting of the sum of any group of

temporal parts, and then identify one of those sums as the person. The question of

whether there is anything that the term ‘person’ can be applied to ceases to exist; there

are many possible candidates the term ‘person’ can be applied to. The hybrid view’s

claim that this set of person-stages, linked by psychological continuity maintained in

virtue of physical continuity, is as good an explanation as any as to which sums of

temporal parts we typically think of as single objects and which we ignore.162

160

Olson (2007), 114-116.

161 Sider (2001), 7.

162 Sider (2001), 7-8; Olson (2007), 116-117.

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The claim that we are temporally extended objects runs into many of the same

objections as the other answers to the question of personal ontology. The issue of too

many thinkers still arises: if any collection of temporal parts adds up to something, but

the only objects that are persons, defined in terms of cognitive capability, are the ones

formed from collections of temporal parts that are psychologically continuous in virtue of

being physically continuous, why aren’t the others also persons? An object consisting of

my temporal parts for the last fifteen minutes plus the temporal parts of my next-door

neighbor from 2011 to 2012 has cognitive capabilities that should qualify it as a person,

too, and it is not identical to me, so it seems we once again wind up with too many

thinkers.163

The reappearance of these difficulties does not mean that the perdurantist should

resist the hybrid view, however; these potential issues are the perdurantist’s to face, as

versions of them arise for virtually any understanding of personal identity the perdurantist

might accept.164

As such, I set them aside; this section’s aim of demonstrating that the

hybrid view is compatible with perdurantism is not dependent upon resolving these

issues.

1.2 Physicalism and Non-Physicalism

In developing the hybrid view, I was careful to make it compatible with

physicalism, the claim that everything that exists is physical. Incompatibility with

163

Olson (2007), 119-122.

164 Olson (2007), 120.

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physicalism would have been reason to discard the view. In spite of this, the hybrid view

does not require commitment to physicalism. Although it cannot accommodate all non-

physicalist understandings of the self, the hybrid view does yield the correct results

according to some versions of non-physicalism, and as such may be considered

compatible with them.

1.2.1 The Hybrid View and Physicalism

According to the hybrid view, our continuity consists in psychological continuity

in virtue of physical continuity. The physical continuity requirement presents no

difficulties for physicalism. If there is to be conflict between the hybrid view and

physicalism, it is likely to arise from the psychological continuity requirement, or the

implications about personal ontology, the question of what we are, discussed in the

previous chapter.

As Derek Parfit notes, one may be inclined to think that a proponent of

physicalism ought to prefer a physical account of personal identity, rejecting

psychological continuity as relevant to our survival through time. However, this is not

the case: a physicalist can accept an account of personal identity based on psychological

criteria.165

Parfit does not elaborate, but a point made by Jaegwon Kim serves as an

illustration: Kim notes that in works of fiction where travel by teleportation occurs, such

as Star Trek, it is an unquestioned assumption that the physical duplicate created at the

destination will also be an exact psychological duplicate, and claims that our acceptance

165

Parfit (1986), 209.

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of this idea suggests comfort with physicalism.166

Regarding teleportation as a way to

travel, rather than a way to die as the hybrid view sees it, also suggests acceptance of an

account of personal continuity based on psychological features alone. This demonstrates

that physicalism and personal continuity based on psychological continuity are not only

compatible, but actually fit well with one another. As such, the hybrid view’s

requirement of psychological continuity does not conflict with physicalism.

It is old news that mental phenomena can be accounted for via physicalism.

One’s preferred way of understanding the mental in physical terms will probably serve

for the hybrid view. The definition of psychological continuity I have used, borrowed

from Parfit, does not make any assumptions incompatible with physicalism:

psychological continuity is simply understood as the holding of overlapping chains of

direct psychological connections, such as memories, intentions, persisting beliefs, desires,

and so forth.167

Any plausible way of understanding mental states in physical terms must

allow for mental states to exist through time. Because psychological continuity criteria

are mental states, this means that accommodating the hybrid view’s psychological

continuity requirement will not be a problem for physicalism.

The hybrid view’s requirement that psychological continuity be dependent upon

physical continuity means that it is able to avoid potential concerns that might arise for an

exclusively psychological view of continuity. One might, for instance, have concerns

about how the possibility of multiple realizability may impact the possibility of

166

Kim (2006), 8-11.

167 Parfit (1986), 205-206.

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psychological continuity. An exact physical duplicate, like a teleporter might create, will

obviously have all mental states at the moment of duplication physically realized in the

same way as the original, because they are physically identical, but since some

exclusively psychological views, notably Parfit’s, allow for the possibility of

psychological continuity occurring from any cause,168

there may be complications for

such views arising from multiple realizability. Consider Dan and Eric from Chapter 3

again – Eric, across the globe from Dan, never having interacted with Dan, develops a

psychology qualitatively identical to Dan’s as an improbably result of a head injury.

Does the fact that Eric’s psychology is qualitatively identical to Dan’s mean that all his

mental states are realized in the same way, too, or is merely having the same mental

states enough, even if they are realized differently? Allowing for psychological

continuity alone as a criterion of personal continuity means that these questions will need

to be answered, but the hybrid view entirely sidesteps these concerns by requiring that

psychological continuity occur as a result of physical continuity.

1.2.2 The Hybrid View and Non-Physicalism

The hybrid view is not compatible with every possible form of non-physicalism,

but will serve for many versions of non-physicalism. Non-physicalism also allows for a

broader range of possible answers for some of the possible objections to the hybrid view

discussed in the previous chapter.

168

Parfit (1986), 282-287.

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Consider the view that each of us has a soul (or mind, Cartesian ego, or any other

nonmaterial, self-composing entity – I will speak of souls just for the sake of brevity).

Or, better to get at what most who accept such a theory think, consider the view that each

of us is a soul – not in the religious sense of the term, but rather, as Anthony Quinton puts

it, “the soul of Plato and Descartes… [which] tends to be identified with the view that in

each person there is to be found a spiritual substance which is the subject of his mental

states and the bearer of his personal identity.”169

If such a view is accepted, the question

of what we are is no longer so difficult to answer – we are souls on this view; the term

‘person’ can be applied to that immaterial entity. The belief that each of us is a soul

could also provide further support for the hybrid view’s insistence on physical continuity

as grounding for psychological continuity. One might argue that the reason why a perfect

physical and psychological duplicate does not stand in a relationship of personal

continuity to the original has to do with a failure to duplicate the immaterial element, the

original’s soul. The original and the duplicate may be exactly alike physically and

psychologically, but the lack of physical continuity – the fact that the duplicate is a mere

duplicate – may mean that the immaterial part is not found in the duplicate, and personal

continuity does not occur between the duplicate and the original. The hybrid view’s

emphasis on the transplant intuition is also explained, given the assumption that the soul

travels with the cerebrum. Thus, on the assumption that the soul is ‘tethered’ to the

physical, the hybrid view will yield the desired results for this sort of non-physical view.

169

Quinton (2008), 53.

184

One might object that, if what makes for our continued existence is our souls, then

the hybrid view is not correct, even if it yields the same results. If we are souls, and it is

souls that are the bearers of psychological continuity, then the physical continuity

requirement is a red herring of sorts – it gives the right results, on the assumption that a

soul is tethered to a particular brain, but it is not what really makes for personal

continuity if what we are is souls. I concede that this is probably correct, but maintain

that the hybrid view is valuable even if this is so: explaining personal identity in terms of

an immaterial part faces difficulties because the soul is “unobservable and so useless for

purposes of identification.”170

If what makes for personal continuity is continuity of the

soul, the hybrid view can still be valuable for tracking where continuity of the soul occurs

(again, this is dependent upon the assumption that the soul is tethered to the physical),

since there is no way to track the occurrence of the soul without making reference to

personal identity, which is of course circular if the soul is considered the criterion of

personal identity. Thus, on such a non-physical view, the hybrid view’s exact

relationship to personal continuity may need to be interpreted differently from how I have

portrayed it, but it may still play a central role with regard to the issue of what sorts of

situations we can survive.

Conflict between non-physicalism and the hybrid view may occur if one holds

that souls are in no way ‘tethered’ to any particular physical body (or rather, any

particular brain). Suppose that one day Anne wakes up in (what had been) Beth’s body,

with no physical change to either body, so we can be sure that this seeming body-swap

170

Quinton (2008), 55.

185

did not occur as a result of Anne’s brain being transplanted into Beth’s body. Because

Anne and Beth do not stand in a relationship of physical continuity, Anne does not stand

in a relationship of personal continuity with Anne-in-Beth’s-body. Anne-in-Beth’s-body

is a new person, because she is neither Anne (lacking physical continuity with her) nor

Beth (lacking psychological continuity with her). Some non-physicalist accounts would

object to this result, claiming that this seeming body-swap could occur if Anne’s soul

moved from Anne’s body to Beth’s. I do not have much to say in response to this. Those

who are committed to this particular non-physicalist account may consider this a reason

to reject the hybrid view. As indicated, then, the hybrid view is not compatible with all

forms of non-physicalism, but some forms of non-physicalism will find that the hybrid

view at least tracks where personal continuity occurs, and will as such be valuable per

those accounts.

2 Ethical Implications

Acceptance of the hybrid view as the theory which underlies our actual practices

concerning personal continuity will have implications reaching beyond metaphysics. The

view may have particular significance in terms of defining the boundaries of life – when

it begins and when it ends – and for moral responsibility and the implications thereof.

If one grants that our approach to these topics is grounded in the way we

understand the continued existence of the self, and accepts the hybrid view as the view

which most plausibly underlies that understanding, then the hybrid view also ought to

influence the way we address these issues.

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2.1 The Boundaries of Life

On its own, the hybrid view need not have any major implications regarding the

beginning and end of life. The hybrid view makes a claim about what we are, but for that

claim to bear on issues regarding the beginning and end of life, there must be a link

established between what we are and those issues. For example, the hybrid view states

that if I were to fall into an irreversible coma, such that psychological continuity with my

present self was no longer possible, I would have ceased to exist. In and of itself, this

does not indicate anything about, for example, the permissibility of euthanasia, the

legitimacy of living wills, or similar. For the hybrid view to have an impact on what we

ought to believe about these issues, it must be established that what matters for these

issues is our personhood, our personal continuity, rather than one of the other relations in

the neighborhood. I have argued that the hybrid view tracks what we care about when it

comes to our own survival, but it may be that in borderline cases like the beginning and

end of life, other considerations come into play. As such, acceptance of the hybrid view

does not necessarily require any particular view on the ethical issues that surround the

start or end of life.

Nonetheless, if I am correct that the hybrid view tracks what we care about when

it comes to our own survival, it is likely to appropriately influence our answers to various

ethical problems in these areas, and it will block some arguments for particular

conclusions about these issues. Any conclusion concerning our moral duties towards

human organisms that are not persons – including fetuses, people with irreversible brain

damage, people in persistent vegetative states and so forth – which relies on claims that

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such organisms are identical to persons is not sound if the hybrid view is correct. As a

brief example, Alexander Pruss’s argument against the permissibility of abortion relies on

the claim that Pruss himself (or any other person) – not some entity that Pruss coincides

with, or is constituted by, or is a part of – was once a fetus.171

But this claim is false if

the hybrid view is correct – Pruss is a person, not a human animal, if the hybrid view is

correct, and although the animal that Pruss the person stands in a unique relationship to

may be identical to something that was once a fetus, Pruss the person is not identical to

that thing, because Pruss is a person (in the sense of possessing certain cognitive and

psychological capabilities), and a fetus is not.

This is not to say that acceptance of the hybrid view is incompatible with the

claim that abortion is impermissible. But it does show that if one is to argue that abortion

is impermissible while accepting the hybrid view, the impermissibility of abortion must

arise from something other than a claim of numerical identity between fetuses and

persons (‘person,’ again, being used in the sense I have used throughout, rather than as a

synonym for ‘human being’). The situation is analogous when it comes to ethical

obligations in the treatment of those who have ceased to be persons: such individuals will

not be stand in a relationship of personal continuity to the persons they once were, but

this does not entail any particular conclusion about what obligations we have towards

them. If I fall into an irreversible coma tomorrow such that psychological continuity is

eliminated, I cease to exist, but on its own, that doesn’t tell us anything about how what

remains – the human animal I was uniquely linked to – ought to be treated, or whether it

171

Pruss (2013), 342-346.

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ought to be regarded as dead. In the next two sections, I will consider the way that the

hybrid view may impact our understanding of death, and the legitimacy of plans we make

for futures when we are mentally diminished.

2.1.1 The Hybrid View and Death

When my brain ceases to maintain my psychological continuity, I cease to exist

per the hybrid view. Suppose, for simplicity’s sake, that this occurs via lobotomy: the

parts of my brain responsible for the maintenance of psychological continuity are

removed and destroyed. But a human animal, which may still be capable of a variety of

functions both life-maintaining (regulation of circulation, breathing and so forth) and

otherwise (making sounds, moving, and the like), may remain, even though I have ceased

to exist. Has a death occurred? If so, what happens when the life-maintaining functions

of that human animal stop? Does this body die a second time?

It may seem obvious that a proponent of the hybrid view should claim that the

death occurs when I cease to exist, rather than when the human animal’s life functions

stop. (In many cases, of course, these events will occur at roughly the same time.) It is,

after all, my death, not the death of some possession of mine, so surely it should occur

when I am no more. However, identifying death as the point at which a person ceases to

exist may lead to more problems than the alternative, according to which a person can

cease to exist without a death occurring. I argue here in favor of the view that death

occurs to human animals, and not, strictly speaking, to us. Although this conclusion

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seems counterintuitive, I will argue that it does not call for the rejection of any strongly-

held beliefs about our own existence.

If death occurs when an individual fails to meet the criteria for personhood, there

will be cases in which it seems obviously true that the individual is alive, but they are

considered dead. This will not be limited to borderline cases of permanently comatose

individuals who may still have the capacity to breathe on their own, for instance – if

death occurs at the point at which the capacity for personhood is permanently lost, then,

for example, a person with severe Alzheimer’s disease, still capable of a wide array of

simple actions, including independent locomotion, but no longer meeting the criteria for

personhood, will be counted as dead. This seems both obviously false and morally

disturbing.172

This view also means that human animals who never meet the criteria for

personhood – the severely mentally disabled, anencephalic infants, perhaps even any

infant who perishes before personhood is attained – were never alive, which again, seems

clearly false and morally dubious.173

Identifying death with the point at which we cease to be person-composing also

has the disadvantage of making our death unlike the death of any other beings. Other

living organisms die when life-maintaining function stops, but, according to this view, we

alone die when they cease to meet the criteria for personhood.174

One might think that

this conclusion is not so untenable, given that per the hybrid view, ‘we’ does not refer to

172

DeGrazia (2005), 127.

173 DeGrazia (2005), 128.

174 DeGrazia (2005), 126-127.

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human animals, but to persons, and as such, it should not be a surprise that the conditions

under which we die are not like the conditions under which other animals die, since we

are not animals. But taking this approach leaves open the concern about what happens

when the life-functions stop in a human animal that has already ceased to be a person: if

we die when personhood stops, but human animals die when breathing stops, we either

get two deaths each, or must deny that anything at all dies when the human animal stops

functioning, which is undesirable given that such an occurrence is clearly death for all

non-human animals. 175

Even this quick sketch of the issues that may arise from identifying death with a

person ceasing to exist shows that the view has considerable difficulties. There are also

other good reasons for the defender of the hybrid view specifically to reject this view. If

the hybrid view is correct, then I cease to exist when psychological continuity in virtue of

physical continuity is lost. But this does not necessarily mean that any death has

occurred. Consider the cases of psychology swaps caused by neurophysical manipulation

of the brain, rather than transplant of the brain.176

If my brain is altered on the

microphysical level such that it still meets the criteria for personhood, but the resulting

person does not stand in a relationship of psychological continuity to me, then it is

especially obvious that a death has not occurred. There is a perfectly healthy, functional

person walking around in my body, even though that person isn’t me. The fact that I

175

DeGrazia (2005), 129-130.

176 I previously discussed this sort of case in Chapter 3, section 2.1.1.

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ceased to exist when my psychological continuity was extinguished does not show that a

death has occurred.

All this adds up to good reason to think that death does not occur when a person

ceases to exist. Can the hybrid view make sense of this conclusion? The best way to

interpret this is to regard death as something that happens to human animals, not to

persons. We, persons, can cease to exist, and what causes us to cease to exist is often the

death of a human animal. But the death of a human animal is not necessarily the

cessation of a person – as when the cerebrum is successfully transplanted into another

human animal’s head, or when the human animal was never a person – and the cessation

of a person is not necessarily the death of a human animal, as when brain injury or illness

causes a person to cease to exist while the human animal continues to function. Is this

picture too implausible to accept? I think it is not. The idea that a person can be gone

without a death occurring is not unfamiliar to those who have witnessed something like

the example of the patient with severe Alzheimer’s, failing to meet the criteria for

personhood but still alive. One might be concerned about the pronouns involved – we

speak of our deaths, not the deaths of our bodies – but this issue can be handled in the

same way that other issues regarding claims that seem to be about us as bodies are

handled. The same way of understanding a claim like “I have hands” or “I am 5’6”” will

also work for claims about death.

It is thus better to identify death with the point at which a human animal stops

functioning, rather than the point at which a person ceases to exist, and as I have argued,

this view is compatible with the hybrid view. What moral implications does this view

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have in conjunction with the hybrid view? Settling on a definition of death appears to

have surprisingly little moral impact. We do avoid potentially problematic conclusions

where humans typically considered alive are regarded as dead; this is an advantage, as we

typically think that even humans who are not persons are deserving of more consideration

that dead humans, even if we also think that dead humans deserve moral consideration.177

But questions as to whether euthanasia is permissible, whether living wills hold under

certain conditions, and so on, are not settled by defining death.

2.1.2 The ‘Someone Else’ Problem

Because the hybrid view requires psychological continuity for personal

continuity, it is potentially subject to what David DeGrazia calls the ‘Someone Else’

Problem. The concern is that any view of identity which calls for psychological

continuity rules out the possibility of making decisions in advance about what will

happen to us when psychological continuity requirements are not met, because the fact

that psychological continuity requirements are not met means that the human animal the

decisions apply to is not us any longer. Suppose that today, I sign an advance

directive/living will indicating that I do not want such-and-such treatment, should my

mental condition be deteriorated past a certain point. But tomorrow, I receive severe

brain damage in an accident, such that psychological continuity is no longer maintained.

Does the advance directive I signed today really dictate what will happen to this badly-

injured individual of tomorrow? Per the hybrid view, that brain-damaged person is not

177

DeGrazia (2005), 127.

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me, because she does not stand in a relationship of psychological continuity to me. As

such, it seems that no matter what I stipulated in my advance directive today, it will not

express the desires of the injured individual tomorrow, because she is not me, and any

decisions I made about what should happen to me are no more relevant to the brain-

damaged individual than a decision my next-door neighbor could make about the injured

person.178

Is there a way for the hybrid view to avoid this concern, or does acceptance of the

hybrid view mean that there is no way to justify caring what happens to us even when we

are no longer persons? Not necessarily. Although the hybrid view does rule out the

possibility of claiming that I can make decisions about what happens to the injured

person tomorrow on the grounds that that person is me, it does not rule out the possibility

of claiming that I can make decisions about what happens to the injured person tomorrow

for some other reason that is uniquely available to me today, rather than some other

person today.

The situation with an advance directive or living will may be compared to the

other sort of will, the document which dictates what happens to one’s possessions after

death. One does not need to believe that persons continue to exist after death to agree

that they can dictate what happens to their possessions once they die. The fact that we

typically acknowledge and respect wills demonstrates that in some circumstances,

someone who does not exist anymore gets to determine what happens to their possessions

after they cease to exist in virtue of the relationship they had to those possessions when

178

Dresser and Robertson (1989), 236; Bluestein (1999), 20-22; DeGrazia (2005), 159-167.

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the person did exist. These things were mine, and that fact means that I get to decide

what happens to them once I do not exist anymore. The hybrid view can regard our very

bodies, even while they still function, in the same way. The brain-damaged individual

tomorrow is not me, per the hybrid view, but the relationship that exists between she and

I is unique to me,179

and for that reason my wishes today dictate what happens to her even

once I no longer exist, in the same way that my wishes today can dictate what happens to

my furniture or books once I no longer exist.

Dresser and Robertson argue that advance directives cannot be understood in the

same way as property wills, because when a property will is enacted, the person whose

will it is cannot be harmed by failure to enact it, while an advance directive is enacted

when the person still has interests.180

This objection does not apply to the hybrid view,

however, because as noted, the damaged individual of tomorrow is not me. That

individual may have rudimentary interests, like trying to avoid pain, but she is not me,

and whatever interests she may have are not mine, meaning that the point of disanalogy

raised is not actually a difference between the cases according to the hybrid view. Thus,

acceptance of the hybrid view does not require us to reject the legitimacy of advance

directives, only to claim that it is grounded in something other than strict identity.

2.2 Moral Responsibility

179

In a case of fission, it would not be unique to one person, but to the two whose hemispheres jointly

make up the resulting brain. It is not literal uniqueness that matters.

180 Dresser and Robertson (1989), 237.

195

It seems obvious that moral responsibility and personal identity are intimately

linked to one another. Some consider moral responsibility central to the notion of

personhood,181

and it is typically considered obvious that we can be held morally

responsible only for our own actions, and as such, can only appropriately be praised or

blamed, punished, rewarded, or compensated, for our own actions, not the actions of

another person. (For example, punishing the family member of a wrongdoer, rather than

the wrongdoer himself, is wrong.) As such, both identity and personhood itself are tied to

moral responsibility. In this section, I will discuss some of the difficulties that various

accounts of personal identity face concerning moral responsibility, then argue that the

hybrid view is able to avoid these difficulties.

When there is doubt about who is responsible for an action in the usual sense –

did Smith or Jones commit the robbery? – it is taken for granted, quite reasonably, that if

punishment is deserved, the one who deserves punishment is the one who committed the

act. In such a case, punishment cannot proceed until it is determined, with a sufficiently

high degree of certainty, who is responsible for the act deserving punishment. We cannot

flip a coin and decide to punish Smith rather than Jones: it is permissible to punish one or

the other only if we are as certain as can be expected that he is the responsible party. In

short, we must know the identity of the responsible party in order to respond correctly.

Obviously, individuals are sometimes punished for actions that they did not take,

but this is not deliberate. The intent is to punish the responsible party, and sometimes

181

Schlossberger (1992), 1, summarizing P.F. Strawson: “to treat someone as a person is, in large part, to

treat her as subject to praise or blame.”

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errors are made. If Smith committed the robbery, but we mistakenly believe Jones

committed the robbery and convict him, the claim that identity is relevant to moral

responsibility is not undermined. Jones is punished only because it is believed,

incorrectly, that Jones is the person who committed the robbery. Jones’s desert of the

punishment is contingent upon his identity as the robber, and since Jones is not the

robber, he is wrongly punished. But if those involved learned that Jones was not the

robber, then they would agree that Jones’s punishment is unjust, because he is not the

responsible party. Who did what (among other factors) dictates who deserves what.

Identity thus has a role to play in everyday cases of assigning moral

responsibility. As in the case described above, if we wrongly believe Jones is the robber

when really Smith is the robber, we may unintentionally administer punishment in an

unjust way, because it is administered on the basis of false beliefs about the identity of

the robber. The type of problem cases that arise in the discussion of personal identity

further complicate the issue by introducing another way in which there may be doubt

about who is the responsible party: even if this body is the body whose finger was on the

trigger, and the body was fully under the control of its owner, who was not being

coerced, during the relevant events, does that tell us for sure that the person to whom this

body belongs is the person responsible?

Per the hybrid view and most of its competitors, it does not. In actual cases where

we attempt to determine who is responsible for a given action, none of the factors which

potentially result in changes of identity occur, and as such none of the questions of

identity associated with personal identity arise. (That is, in our robbery case and other

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typical cases, there is no disruption of either psychological or physical continuity, and as

such, we do not need to worry if Smith-at-the-time-of-the-robbery is the same person as

Smith-now.) However, if there were disruptions of either psychological or physical

continuity, it would be inappropriate to ignore the way that the identity of the individual

may impact her desert.

Suppose that Smith, a notorious criminal, is on the run from the law after robbing

a bank. But the getaway car is involved in a collision, and Smith is decapitated in the

gruesome accident, his skull crushed. Meanwhile, across town, Jones, an admirable

individual in all ways, has just been trapped beneath a falling piano, crushing his body.

The two cases come in to the hospital at the same time. The doctors are able to perform a

life-saving procedure, attaching Jones’s head to Smith’s body so that Jones’s brain now

controls Smith’s body, in the same way that a brain typically controls the body it is

attached to. Later, the police come by and arrest the recovering individual – call him

Smones – for the bank robbery. After all, Smones’s hands are the same hands which held

a gun to the teller in the bank robbery, and carried the sack of stolen money. Smones’s

feet are the feet that moved this body into the getaway car.

In a case like this, it is immediately apparent that something has gone wrong:

although Smones’s hands are indeed the hands that were once Smith’s, this does not

make Smones, who has Jones’s head, and as such Jones’s personality, memory and so

forth, responsible for what Smith did with his hands or the rest of his body prior to

becoming Smones. The fact that these hands, these feet, were involved in the

commission of a crime does not, on its own, make the current owner of these hands and

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these feet responsible for the acts these hands and feet were involved in. It is worth

noting here that this sort of consideration is not merely hypothetical: executed criminals’

body parts have been used for donation in the past. For example, the corneas182

and

several other internal organs183

of convicted murderer Gary Gilmore were used for

transplant following his execution. Corneas and livers and the like obviously are not so

actively involved in the commission of crimes the way that we might say hands or whole

bodies are, but there is no reason to think that hand, limb or even whole-body transplants

will not occur in the future, with criminals as the donors in some cases.

It would clearly be ridiculous to hold a person responsible for Gary Gilmore’s

crimes on the grounds that he received Gilmore’s corneas or liver. The same applies in

the case of Smith and Jones. Fortunately, the transplant intuition, the hybrid view, and

nearly all of its competitors agree: Smones is Jones, not Smith. Punishing Smones, and

thereby Jones, for the crimes Smith committed is clearly unjust under any plausible

understanding of moral responsibility.

2.2.1 Moral Responsibility and Accounts of Personal Identity

The case of Smones, Smith and Jones demonstrates the role that personal identity

has to play in moral responsibility, but it does not distinguish the hybrid view from its

competitors. Because Jones’s entire head, with brain intact and functioning normally,

was transplanted onto Smith’s body, virtually all the views I have discussed agree that

182

Breslin (1977).

183 Johnston (1977).

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Smones is Jones, not Smith, because Smones meets the criteria for being Jones, and not

Smith, by several different standards. Smones has Jones’s brainstem, Jones’s cerebrum,

Jones’s memories, and so on. These considerations do not come apart in Smones’s case,

so this case does not reveal the particular strength that the hybrid view has in dealing with

moral responsibility and moral desert. However, in cases where these criteria come apart,

the hybrid view’s competitors struggle with attribution of moral responsibility in cases

where the hybrid view does not.

To illustrate this, consider a variant on the situation described above. Imagine

now that Smith was not entirely decapitated in the accident: although the parts of the

brain responsible for psychological characteristics were destroyed, other parts of his

brain, including the brainstem, are intact, as well as the rest of his body. Meanwhile,

Jones is in worse shape than in the original case: in addition to his body being destroyed,

his brainstem has also been irreparably damaged. Doctors transplant the remaining parts

of Jones’s head, including the cerebrum but not the brainstem, onto Smith’s body,

attaching them appropriately so that Jones’s cerebrum stands in the relationship to

Smith’s body and other brain parts that a cerebrum stands to a body and brain in typical

cases. Call the resulting person in this case Smones2. Once more, the police arrive at the

hospital to arrest Smones2 for the murder that Smith committed. Is it appropriate to hold

Smones2 responsible for the crime that Smith committed? Can Smones2 justly be

punished for the act Smith committed?

According to animalism, Smones2 is identical to Smith, not Jones, because the

identity of the animal is determined by continuity of a life, maintained by the brainstem.

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Smones2’s brainstem is Smith’s brainstem, so Smones2 is Smith, regardless of the fact

that Smith’s brainstem is now maintaining function in Jones’s cerebrum, not Smith’s.

The organism whose life continues on in Smones2 is Smith, not Jones. Given the

plausible initial assumption that identity is relevant to personal responsibility and desert

of punishment, it seems that animalism says that Smones2 may be punished for the

murder, because Smones2 is Smith and Smith is the responsible party, while the

psychological continuity view says that Smones2 cannot be punished for the murder,

because Smones2 is Jones and thus not responsible for the murder.

The biological view’s outcome seems to be incorrect here. Smones2’s situation is

like Smones’s – he should not be held responsible for the actions that his body was

previously involved in, even though those actions were done freely and in accordance

with the intentions of the person who owned the body at the time. The intentions which

led Smith to commit the murder are entirely absent from Smones2, just as they are absent

from Smones. Smones2 has a little more in common with Smith than Smones does with

Smith, since Smones2 has more of Smith’s parts than Smones does, but the addition of

Smith’s brainstem does not seem sufficient to make Smones2 responsible or deserving of

punishment for Smith’s actions, any more than a person is responsible for the actions

taken by a person who has donated a heart or kidney to her. In his account of animalism,

Olson acknowledges that the numerical identity of human beings may not align with our

practical concerns,184

and the schism between our concerns and animalism is particularly

apparent when it comes to attributions of moral responsibility. Accepting animalism

184

Olson (1997), 44.

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seems to require that we either hold Smones2 responsible for Smith’s crime, or reject the

very plausible claim that identity is relevant to moral desert.

Any non-reductionist accounts of personal identity which holds that we are

essentially featureless nonmaterial entities like souls will face a similar difficulty.

Though not all non-reductionist accounts identify us with featureless souls that bear

neither psychological nor physical continuity, some do, and it seems inappropriate to

identify these featureless souls as bearers of moral responsibility.185

If a soul could bear

moral responsibility, it would allow for the possibility of holding me responsible for

things that happened before I was born, if the featureless nonmaterial entity I was

identical to was also identical to the person whose actions I am being held responsible

for. This concern is similar to the point Locke raises against the idea that personal

identity could be understood as the identity of a featureless soul, lacking psychological

continuity from one life to the next:186

if I do not have any psychological continuity with

the previous ‘owners’ of my soul, is the fact that I share a wholly featureless soul with

them meaningful with regard to personal identity? Can I properly be held responsible for

the actions of people who died centuries before I was born? Surely not.187

If I were

essentially a soul, the reasonable conclusion to draw would be that what I am essentially

185

D. Shoemaker (2007), 320.

186 Locke (2008), 43-44.

187 Those who believe in reincarnation such that what one gets reincarnated as is determined by one’s moral

status in a past life may disagree with this claim. This is not a problem for my claim here; such beliefs

represent a distinct take on what matters for survival, and not what the hybrid view or its competitors aim at

capturing.

202

is not relevant to moral responsibility, not that I can be held responsible for the actions of

my soul at times I have no other continuity with.

Both animalism and the idea that we are featureless nonphysical entities struggle

with proper attribution of moral responsibility; each seems to fail due to the absence of

psychological continuity. (When physical continuity occurs with psychological

continuity, attributing moral responsibility seems perfectly appropriate; similarly, if my

soul behaves badly and I am psychologically continuous with its time of bad behavior,

holding me responsible seems far less dubious.) However, the other extreme, where

psychological continuity alone is the bearer of moral responsibility, also seems dubious.

Suppose that I am kidnapped off the street by a nefarious neurosurgeon. He

overwrites my psychology with the psychology of a serial killer. Is it now appropriate to

hold the resulting occupant of my body responsible for the serial killer’s murders? I

maintain that it is not. Although the occupant of my body is no longer me (assuming that

my psychology was destroyed by the overwrite), the occupant is also not the serial killer,

even if the original serial killer went out of existence at the very moment my psychology

was overwritten with his. Bearing the psychology of a serial killer likely makes the new

occupant of my body a dangerous person, one it would be prudent for law enforcement to

keep an eye on, but the resulting person is not actually responsible for the serial killer’s

killings, because there is no causal relationship between her and the killings. Moral

responsibility depends on a causal relationship between action and agent, and the causal

relationship that exists between an agent and her actions is not carried over to a

psychological duplicate, even one which is perfectly identical to her.

203

A view like Locke’s or Parfit’s, according to which psychological continuity is

enough to constitute survival, also struggles with attributions of moral responsibility.

Joseph Butler criticizes Locke’s view by claiming that the view means “it is a fallacy

upon ourselves, to charge our present selves with any thing we did… yesterday,”188

asserting that if we are not numerically identical to our past selves, the relationship we

stand in to our past selves is not sufficient for moral responsibility to hold. Parfit

summarizes Thomas Reid’s criticism of Locke: if Parfit’s view is true, “it is not merely

true that we cannot be ‘accountable’ for past crimes. All rights and obligations are

undermined.”189

Parfit notes that contemporary philosophers have raised similar

concerns about his view, going so far as to claim that morality is incompatible with a

view of identity grounded in psychological continuity.190

Parfit maintains that a change in our understanding of moral responsibility may be

necessary if his view is true, but denies that this is grounds for rejecting his view,

suggesting instead that our existing understanding of morality is based upon a flawed

conception of the relationship of personal identity and responsibility. Parfit does not

offer much defense for this claim, merely noting that although the claim that numerical

identity is necessary for responsibility is defensible, so is its denial. He does assert that

responsibility and desert of punishment diminish as psychological continuity diminishes:

the less strongly an individual is psychologically connected to the wrongdoer, the less

188

Butler (2008), 102; referenced in Parfit (1986), 323.

189 Parfit (1986), 323, summarizing Reid (2008), 112.

190 Parfit (1986), 323.

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punishment she deserves. Parfit supports this claim by citing Statutes of Limitations as

evidence that one’s desert for a crime can diminish. He illustrates this with the example

of an eighty-year-old man who is a deserving recipient of the Nobel Peace Prize, but got

into a brawl at age twenty. 191

Parfit’s conclusion that the old man should not be

punished for his wrongdoing at age twenty is certainly the plausible conclusion, and it

supports his claim that psychological characteristics may be relevant in diminishing one’s

responsibility for past acts.192

Parfit clearly does not mean to persuade anyone to his

view in virtue of its stance on moral responsibility, merely to illustrate the consequences

his view would have for moral responsibility. However, if we are to evaluate the

psychological continuity view on the basis of the way it handles moral responsibility, it

does not fare well. It is strongly counterintuitive, and unless one is already persuaded to

the view for other reasons, Parfit’s claims that we ought to adjust our beliefs about moral

responsibility to suit the view are difficult to accept.

191

Parfit (1986), 323-326.

192 The case of the old man supports the claim better than the Statute of Limitations point he uses the old

man’s case to illustrate, since it is likely relevant to our assessment of the man’s desert that he is a very

different person now: not just older, but a Nobel Peace Prize winner rather than a brawler. Statutes of

limitations do not call for psychological change of any particular sort, just the passage of time, which will

inevitably result in psychological change in a typical case. Would we be just as sure that no punishment is

deserved for the brawl 60 years ago if the eighty-year-old were still getting into brawls, or had moved on to

more serious infractions? I suspect most would say the crime is still too long ago for punishment to be

deserved for it, but it should be noted that Parfit’s example includes more than just the passage of time, but

psychological change for the better.

205

Thus, both views which call for strict numerical identity of a part (either a

physical part, as with physical continuity views, or a nonmaterial part, as with non-

reductionist views), and psychological continuity views falter when it comes to

supporting our beliefs about personal responsibility. The hybrid view is particularly

well-suited to handling these concerns, since what the former group lacks is

psychological continuity, and what the latter lacks is a causal connection between the

acting agent and her psychological duplicates. For incorporating both physical continuity

(which ensures at least partial identity and may thus be able to secure the necessary

causal connection) and psychological continuity (which eliminates the possibility of

holding human vegetables or blank-slate souls responsible for actions they are not

psychologically connected to), the hybrid view avoids both issues, neatly fitting almost

all of our existing intuitions about the relationship between moral responsibility and our

own existence through time.

2.2.2 Moral Responsibility and the Hybrid View

The hybrid view gets it right in the cases of Smones2, and the serial-killer

personality overwrite where the others views give the wrong result for one of the cases.

Because Smones2 is psychologically continuous with Jones in virtue of physical

continuity of the cerebrum, Smones2 stands in a relationship of personal continuity to

Jones, and not Smith; as such, holding him responsible for Smith’s crime is unjust, as our

intuitions suggest. The hybrid view also yields the desired result in the case where my

personality is overwritten with that of a serial killer: the resulting person is likely a

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dangerous person, but is not responsible for the crimes committed by the serial killer, and

as such, cannot be considered morally responsible for those crimes. So far, so good. The

other views faltered for failing to include both physical and psychological continuity; the

hybrid view, calling for both, gets the right result in these cases.

However, there are cases where the hybrid view’s result is less plausible. Let us

return to the criminal Smith again, but now, suppose that Smith is a philosophy-savvy

criminal. He is not injured in his escape from the scene of the crime, and makes it safely

to the top-secret laboratory where he has made arrangements to avoid punishment for his

crime with the help of a corrupt neuroscientist. Using highly advanced technology, he

has the exact state of his brain recorded, then has his psychology eradicated from his

brain, rendering his brain a blank slate. Smith’s neuroscientist accomplice makes sure

that the blank-slate condition of Smith’s brain is thoroughly documented, then uses the

recorded information about Smith’s brain state to restore Smith’s psychology to the

blanked-out brain. Per the hybrid view, the resulting person is not Smith, although he has

both Smith’s brain and Smith’s psychology; Smith ceased to exist when his psychology

was destroyed from the brain. The psychological continuity with pre-wipe Smith is not

in virtue of the physical continuity, and thus, the man who wakes from the procedure

(call him Sleepy), is not Smith, and thus cannot be considered responsible for the crimes

Smith committed, even as he chuckles in satisfaction at getting away with Smith’s

crimes. Is this the correct way to regard this case? Should we really say that Sleepy is

not responsible, bearing in mind that Smith knowingly and deliberately caused the

disruption to his continuity for precisely this reason?

207

The hybrid view says so, and I will argue that this conclusion is not as implausible

as it may seem. When it comes to the morality of punishment, we do not hold people

responsible for what they think they have done, only what they have actually done. Our

criminal, after his memories have been restored, has a psychology exactly qualitatively

similar to the psychology he would have if the mind-wipe never occurred, but it cannot

be assumed that this makes him responsible, and deserving of punishment, for the actions

of the person his psychology is exactly similar to.

To demonstrate this, consider the case of Johnson. Johnson regularly confesses to

crimes he did not commit. Whenever he learns that the police are seeking information on

a crime, he shows up at the police station, eager to confess, only to be sent away when it

becomes apparent that he could not have committed the crime in question. Suppose that

Johnson is sincere in his confessions: due to some mental abnormality, Johnson

genuinely believes he has committed the crimes he confesses to. Are the police doing

something wrong in sending Johnson away rather than arresting him? Should the courts

be trying and convicting Johnson? Obviously not. Whatever Johnson may believe, he

simply does not stand in the right relation to the crimes committed to be held responsible

or punished for them. His beliefs about his own guilt are false, mere delusions, and as

such, provide no basis for attributing personal responsibility or desert of punishment. So

far, so good.

Now suppose that Johnson does not merely believe that he has committed a crime.

He is, in fact, psychologically identical to our murderer Smith just after Smith committed

the crime. There is no causal connection to explain why Johnson’s psychology is

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identical to Smith’s. Johnson does not know Smith and has never interacted with him in

any way. It is just one more manifestation of Johnson’s delusions, and purely

coincidental that his psychology is identical to Smith’s post-crime. Can we hold Johnson

responsible and punish him for Smith’s crime?

The answer here may be less obvious than in the previous case, where Johnson

confesses to any crime he hears of, but it should still be no: Johnson cannot be held

responsible for Smith’s crime. The fact that Johnson has a psychology exactly identical

to a criminal’s may have moral implications. It may make him a dangerous individual,

and it may be prudent for the law to keep an eye on Johnson. However, just as Johnson

cannot be held responsible for the crimes he confesses to whenever the police are seeking

information about a crime, Johnson cannot be held responsible for the crime Smith

committed. A specific type of causal connection must exist between an individual and

the actions that individual is held responsible for, and no such connection exists in this

case. Johnson’s psychology is qualitatively identical to the psychology of Smith, who

stands in such a causal connection to the crime, but the personal responsibility that comes

with this causal connection does not carry over to Johnson.

My claim is that the restored Smith, Sleepy, is like Johnson: although once his

psychology is restored, he will be psychologically identical to someone causally

connected to the crime – namely, Smith prior to the brain-wipe – the personal

responsibility that arises from that causal connection to the crime does not carry over as a

result of the psychological continuity. When Smith had his brain wiped, he effectively

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committed suicide, causing himself to cease to exist.193

The fact that something else

happened to his brain after, something that made it exactly resemble his brain prior to the

wipe, does not change the fact that he ceased to exist. The restored criminal Sleepy is not

the same person as the original, and cannot be held responsible for the original’s crime, in

spite of the fact that the restored criminal likely feels very smug about this, thinking that

he has gotten away with something.

This claim is probably one of the most difficult ones to sell. Those who accept

that Johnson is not responsible for Smith’s crimes, in spite of having a psychology

exactly identical to Smith’s after Smith committed the murder, may find Sleepy’s case

different enough that the same conclusion does not apply. I will consider the factors

which distinguish the two cases and attempt to show that they do not undermine my

claim that Sleepy is like Johnson, and offer an alternative justification for how it may be

permissible to administer punishment in Sleepy’s case.

There are two important differences between the Smith/Johnson case and the

Smith/Sleepy case. Johnson and Smith do not stand in a relationship of physical

continuity with one another, whereas Sleepy does stand in a relationship of physical

continuity with Smith before the brain-wipe procedure. Second, in the case of Sleepy,

unlike Johnson, a deliberate decision for the purpose of escaping punishment led to the

Sleepy having a psychology identical to a criminal. Johnson came to have Smith’s

psychology purely by accident.

193

Due to the considerations discussion in 2.1.1, it is better to say that Smith did not actually die, just cease

to exist, since no organism died when Smith’s psychology was destroyed.

210

Per the hybrid view, the lack of physical continuity between Johnson and Smith is

potentially important: because physical continuity is a necessary condition for personal

continuity, the fact that Johnson and Smith do not stand in a relationship of physical

continuity eliminates the possibility of personal continuity between them before we get to

the question of whether the psychological continuity between them arises from physical

continuity: it does not, because there is no physical continuity between them. But in the

Smith/Sleepy case, Smith arranges to have his psychology rewritten onto the very same

brain, in the very same body (give or take a few particles lost and gained in the usual

fashion), from which it was recorded and then erased. Thus, unlike Johnson and Smith,

Sleepy meets two of the three necessary conditions for personal continuity, failing only

the condition that his psychological continuity with Smith is in virtue of his physical

continuity with Smith. It may be that our sense that Sleepy should be punished in spite of

not standing in a relationship of personal continuity with Smith at the time of the crime

comes from the fact that Sleepy comes closer to meeting the criteria for personal

continuity than Johnson does with Smith. Although I will not argue this approach, one

might claim that something less than personal continuity can be sufficient for some

reduced degree of moral responsibility.

The fact that in Sleepy’s case, unlike in Johnson’s case, someone deliberately

elected to cause Sleepy to have a criminal psychology may also be considered relevant.

Johnson came to have the psychology of a criminal unintentionally, whereas in the

Smith/Sleepy case, Smith made arrangements to be sure that his criminal psychology

would be restored to him. Can this difference justify regarding our criminal as

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responsible while Johnson is not? I don’t think it can. The reason for this is that we can

modify the Johnson case so that this disparity is eliminated. Suppose now that Johnson

came to have Smith’s psychology not by virtue of a bizarre coincidence of his delusions

and Smith’s mind, but because he went down to the local neuro-mart and opted to have

Smith’s psychology “installed” onto his brain.194

Should we hold Johnson responsible

for Smith’s crime when Johnson deliberately caused himself to have Smith’s

psychology? The answer, again, seems to be no: although Johnson might plausibly have

done something immoral in causing himself to have a murderer’s psychology, he still

lacks any type of causal connection between Smith’s crime and himself. Although his

psychology is a perfect duplicate of Smith’s, he himself was not actually involved in the

murder in any way, and cannot be held responsible for the murder Smith committed, even

though he deliberately caused himself to have Smith’s psychology, which may be wrong.

So even when Johnson deliberately chooses to have Smith’s psychology, he does

not become responsible for Smith’s past actions. Sleepy’s situation is the same: even

though Smith elected, prior to the brain-wipe, to have his criminal psychology reinstated

into his blank brain, the fact that he deliberately caused Sleepy’s psychology to be

identical to a criminal’s is not sufficient to make Sleepy responsible for the crimes

committed by that criminal. In ensuring that Sleepy will have a criminal psychology,

Smith may well have done something immoral, but Sleepy, post-restoration, is not

responsible for the crime pre-restoration according to the hybrid view.

194

This causes Johnson to cease to exist, but I will continue to refer to the resulting person as Johnson since

it makes no difference here.

212

However, the fact that Sleepy cannot be held morally responsible for Smith’s

crimes according to the hybrid view need not preclude the possibility that Sleepy can

justly be punished. In discussing the moral responsibility and desert of punishment of the

various parties thus far, I have assumed a retributivist approach to punishment. An

alternative understanding of punishment may allow us to decide that Sleepy can justly be

punished while Johnson cannot. Specifically, a deterrence view of punishment may make

punishing Sleepy just. The fact that Johnson bears the psychology of a criminal is due to

an unfortunate abnormality in his brain, not a misdeed on anyone’s part.195

But the fact

that Sleepy bears the psychology of a criminal is a result of the misdeeds Smith arranged

for. It might thus be permissible to punish Sleepy, not because he is in fact morally

responsible for the crimes Smith committed, but to deter other people like Smith from

using this method of avoiding punishment. 196

This approach will lead to potential

concerns about unjust punishment – if Sleepy is not responsible for what Smith did, can it

really be just to punish him? – but it does provide one possible justification for punishing

Sleepy and thereby blocking Smith’s way of avoiding punishment.

If none of the above is persuasive, a small modification to the case may shift

one’s intuitions. Suppose that, rather than considering whether Sleepy is morally

responsible for a crime committed by Smith, we are considering whether Sleepy is

195

In the version of this case where Johnson deliberately comes to have Smith’s psychology, his situation

will be comparable to Sleepy’s.

196 Thanks to C.D. Meyers and other commenters at the 2013 Midsouth Philosophy Conference for the

suggestion.

213

morally responsible for a good deed Smith did. Should Sleepy reap the benefits of

Smith’s good deed? It is again illuminating to compare Sleepy – who has Smith’s

psychology on Smith’s brain, but not in virtue of having Smith’s brain, since it had to be

“installed” by a neurosurgeon – to an unrelated person. Let’s take Johnson again, but

imagine that he, wanting to receive praise, deliberately sets out to have his own

psychology completely and permanently overwritten by Smith’s, knowing that Smith has

recently done a good deed. In this case, it seems obvious that Johnson is not deserving of

praise for Smith’s action. Now compare Sleepy to Johnson – is the fact that Sleepy’s

brain is physically the brain that was in Smith’s head when he did the good deed,

although it has altered so that psychological continuity has not been maintained, enough

of a difference between Sleepy’s situation and Johnson’s for Sleepy to deserve praise

though Johnson does not? I think it can’t be. The brain, separated from the

psychological features it bears in a typical case, is not an appropriate bearer of moral

responsibility; it’s effectively a piece of meat, when it has been stripped of psychological

features. This modification of the case reflects a phenomenon in our moral intuitions

observed by Joshua Knobe: we are more likely to attribute blame than we are to attribute

praise in a parallel situation.197

With this tendency in mind, it may be appropriate to

revise one’s intuitions about whether Sleepy deserves blame or punishment in the crime

case, since it seems that he does not deserve praise or rewards in the good deed case. If

so, the hybrid view’s claim that Sleepy does not deserve to be punished for Smith’s crime

197

Knobe (2003), 193.

214

(though it may be permissible to punish him for deterrent purposes) should seem more

plausible.

Acceptance of the hybrid view may have interesting results with regard to mental

illness and/or mental deterioration and moral responsibility. If one’s mental states have

changed enough that psychological continuity no longer obtains – whether it is because

some other psychological continuity has taken its place, or due to a deteriorative

condition like Alzheimer’s – they cannot appropriately be held morally responsible for

the actions of the person that they no longer stand in a relationship of psychological

continuity to. This reflects the sense that many people have that it is not appropriate to

keep a criminal who is suffering from advanced Alzheimer’s or a similar condition

imprisoned for the crimes he can no longer remember committing.

2.3 Future Technology

According to the hybrid view, teleportation, as it is most plausibly understood (so

that a scan is made of the exact state of a body at the departure location, and a perfect

duplicate is created from local material at the destination location) is not a way to travel

but a way to die. I argued previously that this consequence does not undermine the

plausibility of the hybrid view. It may have some interesting ethical implications,

however.

If teleportation is a way to die – you get yourself shattered on the atomic level,

and whoever it is that steps out on the other end, it isn’t you, however deeply they believe

otherwise – should it be considered immoral to teleport another person? To attempt to

215

develop teleportation technology? Here, recalling the limits of my claim about the hybrid

view become relevant. My claim is not that the hybrid view reflects some deep and

necessary truth about us: it is the most metaphysically coherent account which maximizes

fit with our existing beliefs about ourselves. I intend it as a formalization, a fleshing-out,

of our actual way of understanding our own continuity through time. I do not maintain

that this is the only way we ever could, or ever will, understand our own continuity

through time. If teleportation technology were readily available, we might plausibly

adjust our attitudes about ourselves and our persistence through time in response, coming

to have different beliefs about ourselves on the basis of what our willingness to teleport

shows us about our own natures. Teleportation kills the thing I mean when I say “I”

based on my actual, present-day understanding of myself, but if I meant something else

by “I,” it might be that this alternate thing is not destroyed by teleportation. It is

plausible that in a world where teleportation were possible, our attitudes about ourselves

would be different, even if that world is the future of the actual world. Perhaps, as Derek

Parfit would have us think, we should not care about dying via teleporter. My claim is

that we do, and the hybrid view reflects it – it reflects our actual understanding of

ourselves. But acceptance of teleportation would (or should) lead to readjusting the way

we understand ourselves, leaving behind beliefs incompatible with this imagined

newfound acceptance of teleportation.

If teleportation is acceptable, if we come not to mind dying via teleporter, so long

as a perfect duplicate is created, then we must revise other beliefs in accordance. We

must consider a duplicate who coexists with an original just as good – the duplicate has

216

an equally good claim at being me (in all the ways that matter) if a teleporter-

manufactured copy is just as good as the original. I maintained that this is implausible

given our current conception of ourselves, and certainly, even with revised attitudes that

allowed for acceptance of a perfect duplicate as another legitimate version of oneself,

there may be difficulties. (I do not want to get ready for bed after an exhausting day only

to find my duplicate sprawled in my bed, taking up the whole space. I do not want to

find that my duplicate is using my computer when I want to use it, has eaten my dinner,

and so forth. For being a separate consciousness, even one that was identical to mine

when we diverged, my duplicate is potentially just as much a nuisance as a non-duplicate

when it comes to coexisting with her. If anything, our extreme similarity, particularly in

the beginning, will make my duplicate more of a nuisance than a non-duplicate, since she

and I will each feel, with equally strong conviction, that we are the rightful owners of the

bed, the computer, the dinner, etc., and the other is the interloper.) Nonetheless, if

teleportation is to be regarded as a way to travel and not a way to die, we must regard my

perfect duplicate as having an equally good claim at being me, even when the duplicate

coexists with me.

As such, the hybrid view does not entail any particular conclusions about the

morality of teleportation technology, since it is likely that the way we understand

ourselves and our continued existence would change if teleportation were a viable reality.

As to the development of teleportation technology, presumably this technology would

have to be tested on people (once that stage of development was reached) who do not

possess the sort of belief about continued existence that may arise once teleportation is

217

available. Suppose we could test teleportation technology now, with our current beliefs

and practices in place. Such a test subject should regard teleportation as death for all the

reasons I have stated, and although there would be benefits to the immediate creation of a

duplicate – his family will be spared the pain of losing him, for instance – he himself

would face the immediate end of his existence. However, this does not demonstrate that

it must be immoral to attempt to develop teleportation technology. An individual

knowingly sacrificing himself for progress is not unheard of, and thus, so long as the

teleportation test subject is fully aware of what he is getting into, acceptance of the hybrid

view does not entail that anything impermissible is involved in such a test. Forcing an

unwilling subject to what he ought to understand as his death would be immoral, but

using unwilling test subjects is often considered immoral when far less is at stake than

death, so the issue is the lack of consent on the test subject’s part, not the fact that death

is the result of the test. As such, there is nothing inherently immoral about developing

teleportation technology, even though it entails death for the “traveler” per what I have

argued is our current actual conception of ourselves.

3 Conclusions

I’ve argued in this chapter that the hybrid view is compatible with a range of

metaphysical commitments in related subjects, and explored the ethical impact that

acceptance of the hybrid view may have. Because the hybrid view, unlike most accounts

of personal identity, emphasizes our actual beliefs, it provides a good basis for

determining how we ought to resolve potential ethical issues related to personal identity,

218

such as the issue of moral responsibility when psychological continuity is disrupted.

Most of the cases I have described will remain hypothetical for the foreseeable future, but

if I am correct that the hybrid view does represent the best formalization of our existing

beliefs, it is applicable to present-day issues as well. A person cannot today try to escape

responsibility by having her psychology erased and then reinstated, but illness and injury

may potentially create analogous situations. Having a theory for how we understand our

own survival based on typical cases, as the hybrid view is, provides a foundation from

which we can determine how we should understand unusual cases and ensure that we

deal with them in a way that is coherent with our existing beliefs and practices on the

subject of our own survival through time.

219

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