The Mind-Body Problem

The Mind-Body ProblemThe Mind-Body Problem

Ned Block

Inverted Earth

Physicalism and FunctionalismPhysicalism and Functionalism

• Physicalism: thesis that everything is physical or supervenes on the physical.

• Supervenience: no two possible worlds can be identical in their physical properties but differ, somewhere, in their mental, social or biological properties: if physicalism is true at our world, then no other world can be physically identical to it without being identical to it in all respects.

A dot-matrix picture has global properties — it is symmetrical, it is cluttered, and whatnot — and yet all there is to the picture is dots and non-dots at each point of the matrix. The global properties are nothing but patterns in the dots. They supervene: no two pictures could differ in their global properties without differing, somewhere, in whether there is or there isn't a dot. [David Lewis]

Physicalism and the Mind-Body ProblemPhysicalism and the Mind-Body Problem

• Are mental states just identical to brain states?

• Problem: It’s logically possible that two guys are in the same type mental state but different type brain states.

• But if M1 = B1 and M1 = M2 it is not logically possible that B1 ≠ B2!

I see a red blob.

I see a red blob.

I see a red blob.

I see a red blob.

M2M2M1M1

Functionalism to the RescueFunctionalism to the Rescue

• Functionalism: what makes something a thought, desire, pain (or any other mental state) depends not on its internal constitution, but solely on its function—the role it plays, in the cognitive system of which it is a part.

• The identity of a mental state is determined by its causal relations to sensory stimulations, other mental states, and behavior.

I see a red blob.

I see a red blob.

I see a red blob.

I see a red blob.

same input

same outputsame output

Multiple RealizabilityMultiple Realizability

• Mental states are like computational states of computers

• The same computational or mental state can be realized by different hardware or brainware!

We’re in the same computational state!




The Problem of QualiaThe Problem of Qualia

• But intuitively there’s more to some mental states than input and output.

• There’s what they’re like for the individual that has them!

• And what they’re like might be different for different people

I see a red blob.

I see a red blob.

I see a red blob.

I see a red blob.

What Block is Doing in This PaperWhat Block is Doing in This Paper

• Block argues that there is an ‘inversion’ argument for qualia realism: the view that there are intrinsic features of our experience—that certain mental states are not merely computational states wholly characterized by input and output conditions.

– If qualia realism is true, functionalism is false

– But even if functionalism is false that doesn’t show physicalism is false

• Block will consider the traditional argument(s) for qualia realism—which are unsatisfactory

• And produce a new inversion argument that withstands objections to traditional inversion arguments.

• The ‘Containment Response’: give up on functionalism as a theory of experience…retaining functionalism as a theory of the cognitive aspect of mind.

Intentional vs. Qualitative ContentIntentional vs. Qualitative Content

• Their experiences have the same intentional content since they both are representations of the University of San Diego.

• They have different qualitative content since what it’s like for one person isn’t the same as what it’s like for the other.

Both of our experiences

represent USD

Both of our experiences

represent USD

But they have different

qualitative content

But they have different

qualitative content

Intentional vs. Qualitative ContentIntentional vs. Qualitative Content

• Intentional content: the way the experience represents the world, e.g. my experience represents the peppers as looking red.

• Qualitative content: what the experience “is like”: if these pictures represent my experience and my inverted-spectrum twin’s, our experiences differ with respect to qualitative content.

• But according to Block my twin’s experience also represents the peppers as looking red: our experiences have the same intentional content.

The Traditional Inverted Spectrum The Traditional Inverted Spectrum ArgumentArgument

[T]he inverted spectrum argument is this: when you and I have experiences that have the intentional content looking red, your qualitative content is the same as the qualitative content that I have when my experience has the intentional content of looking green.

Intentional content comes from functional role, i.e. aptness to be produced by certain inputs and to produce certain outputs.

If an inverted spectrum is possible, then experiental contents that can be expressed in public language…are not qualitative contents but rather intentional contents.

Block’s “Quasi-Functional” Qualia RealismBlock’s “Quasi-Functional” Qualia Realism

[T]he intentional content of experience is functional. An experience has the intentional content of looking red if it functions in the right way—if it is caused by red things in the right circumstances, and used in thought about red things and action with respect to red things rightly.

[T]he qualitative content of experience is not functionally characterizable. Two experiences can differ functionally, hence have different intentional contents, but have the same qualitative content, that is, be alike in ‘what it is like’ to have them. Further, two experiences can be alike in function (and hence have the same intentional content), but have different qualitative contents.

• Block has to show that there can be cases where experiences that have same intentional content have different qualitative content or that same qualitative content but different intentional content.

• The problem is that since qualitative content is private, interpersonal comparisons are questionable and even intrapersonal comparisons may be challenged.

Traditional Interpersonal CaseTraditional Interpersonal Case

[I]magine genetically identical twins one of whom has had color inverting lenses placed in its eyes at birth…[A]s adults they both apply ‘red’ to red things in the normal way. But though the twins are functionally identical in the relevant respects, we may suppose that the internal physiological state that mediates between red things and red utterances in one is the same as the internal physiological state that mediates between green things and green utterances.

• When the intentional content of their experiences is the same they’re in different brain states.

I see a red blob.

I see a red blob.

I see a red blob.

I see a red blob.


• So when they sincerely report ‘red’ they’re in different brain states and

• When they’re in the same brain state they’re in different intentional states and report seeing different colors.

• When TwinLeft is in the same brain state that TwinRight is in when he reports seeing red, TwinLeft reports seeing green.

I see a green blob.

I see a green blob.

I see a red blob.

I see a red blob.


• But his doesn’t establish they have inverted qualia…or, indeed, any qualia at all!

• The functionalist will read this as a case of multiple realizability.

I see a red blob.

I see a red blob.

I see a red blob.

I see a red blob.

? ?

Traditional Intrapersonal CaseTraditional Intrapersonal Case

• First, we have a functionally normal person

• Second inverting lenses are placed in his eyes and he says grass looks red and blood looks green

• Third, after a period of confused use of color terms, he finally adapts to the point where he uses color language normally…at the third stage, he is functionally normal except…he recalls the period before the insertion of the lenses as a period in which ‘grass looked to me the way blood now looks.’

• Fourth, he has amnesia about the period before the lenses were inserted and is functionally totally normal.

Is his spectrum inverted at the end of the story? e.g. when he reports “red” in the presence of red objects, is he in the same intentional state he used to be in when he reported “red” but in different qualitative state?

Traditional Intrapersonal CaseTraditional Intrapersonal Case

• Inconclusive again!

• “after a period of confused use of color terms, he finally adapts to the point where he uses color language normally…at the third stage, he is functionally normal except…he recalls the period before the insertion of the lenses as a period in which ‘grass looked to me the way blood now looks.’”

• The functionalist will claim that this is a misdescription: the guy is subject to a memory malfunction and is confused.

• The problem is that both traditional cases beg the question: they assume individual’s psychological states have intrinsic qualitative content as well as well as functional character: this is just what the qualia realist wants to argue for—and what the functionalist will deny.

Inverted EarthInverted Earth

• We have to establish the possibility of inverted spectra without presupposing qualia in order to avoid begging the question

• To argue for qualia realism, we need a case where same intentional content and same qualitative content pull apart.

• Both traditional interpersonal and intrapersonal cases which purport to show same intentional content but different qualitative content are inconclusive so

• Let’s try same qualitative content different intentional content—the Inverted Earth Case where we have persons (or stages of the same person) whose experiences are functionally and intentionally the same but qualitatively inverted.

Inverted EarthInverted Earth

• Colors are inverted

• But color language is also “inverted”

• These two differences “cancel out”

Differences “Cancel Out”Differences “Cancel Out”

Talk on inverted earth will sound just like talk on Earth. Radio programs from Inverted Earth will sound to us like radio programs from far away places where English is spoken…Children on both planets ask their parents “Why is the sky blue?

The Inverted Earth Thought ExperimentThe Inverted Earth Thought Experiment

A team of mad scientists knock you out…insert color inverting lenses in your eyes and change your body pigments so you don’t have a nasty shock when you wake up and look at your feet. They transport you to Inverted Earth…As far as the qualitative aspect of your mental life is concerned, nothing is any different from the way it would have been had you stayed home…

What about the intentional content of this experience?...your use of ‘blue’ is grounded in references to blue things and to the uses of ‘blue’ by other people to refer to blue things. For this reason, I would say that on your first day on Inverted Earth, your intentional contents remain the same as they were—that is different from the natives…

Nevertheless, according to me, after enough time has passed on Inverted Earth, your embedding in the physical and linguistic environment of Inverted Earth would dominate.

This is enough to refute the functionalist theory…[and] establish the intentional/qualitative distinction.

The Qualitative Content of ExperienceThe Qualitative Content of Experience

A team of mad scientists knock you out…insert color inverting lenses in your eyes

• If you stayed on earth, everyone would agree that the character of your experience is different from what it was before the lenses were inserted, right?

They transport you to Inverted Earth…

• Merely moving you from one place to another, without any other changes to you or the inverting lenses, won’t change the character of your experience, right? Or is this illegitimately assuming that there is a character of your experience?

As far as the qualitative aspect of your mental life is concerned, nothing is any different from the way it would have been had you stayed home…

• Because Inverted Earth is color-inverted, the difference “cancels out.”

The Intentional Content of ExperienceThe Intentional Content of Experience

What about the intentional content of this experience?...your use of ‘blue’ is grounded in references to blue things and to the uses of ‘blue’ by other people to refer to blue things.

• Meanings are not (entirely) in the head: what I mean depends on the circumstances in which I learnt language and the practices of my linguistic community

• When an ordinary English-speaker on Earth says “blue” he means the color of objects that other ordinary English-speaking Earthlings call “blue”

For this reason, I would say that on your first day on Inverted Earth, your intentional contents remain the same as they were—that is different from the natives…

• Your linguistic community on arrival is still Earthlings: what you mean is still “grounded” in their linguistic usage.

Inverted Earth: Intra-Personal CaseInverted Earth: Intra-Personal Case

Nevertheless, according to me, after enough time has passed on Inverted Earth, your embedding in the physical and linguistic environment of Inverted Earth would dominate.

• Once you’ve gone native, participated in many conversations with Inverted Earthlings, your linguistic usage is re-grounded.

• There may be a period when there isn’t a right answer to the question of what you mean by, e.g. “blue”

• But does that matter?

Inverted Earth: Intra-Personal CaseInverted Earth: Intra-Personal Case

This is enough to refute the functionalist theory…[and] establish the intentional/qualitative distinction.

• Your qualitative state is seeing blue

• Your functional state is the same as the functionalstate of natives when they see yellow things

• You’ve gone native and are now amember of their linguisticcommunity so

• When you say “blue” you mean the samething that they do.

Earthling with color-inverting lenses

blueblue

The Inverted Earth ArgumentThe Inverted Earth Argument

• Same qualitative state, Q – different functional states, F1 and F2

• If F1 = Q and Q = F2 then F1 = F2 [by transitivity of identity]

• But F1 ≠ F2 so NOT(F1 = Q and Q = F2) [by modus tollens]

Earthling with color-inverting lenses Inverted-Earthling

blueblue yellowyellow

Interpersonal Case: You and your Inverted Interpersonal Case: You and your Inverted TwinTwin

Though you and your twin have the same qualitative contents at every moment, you are inverted functionally and with respect to intentional contents of experience.

You grew up on Earth She grew up on Inverted Earth

The sky here is

blue

The sky here is

blue

The sky is blue here

too


too

Objection: Objection: whichwhich functional description? functional description?

There are a variety of functional descriptions according to which you are functionally the same as Twin…[A]ny functional description that draws the line between the inside and the outside at the surface of the brain will be a functional description according to which you and Twin are functionally the same.


The sky here is

blue

The sky here is

blueThe sky is blue here

too


too

Response: It’s “long-arm” states that countResponse: It’s “long-arm” states that count

Brain-internal functional states cannot capture the intentional content of experience


The sky here is

blue

The sky here is

blue


too


too

Spectrum Displacement ArgumentSpectrum Displacement Argument

If * is the neural signal that we are counting as input to your brain, * would be produced by red in your brain, by yellow in one of your clones, and by blue in another clone. So neither * nor any brain-internal functional state triggered by it can correspond to any single color in the world…all internal functional descriptions will be shared by all of you. So no purely brain-internal functional description can capture the intentional content of experience.

If intentional contents of experience are functional states they are ‘long-arm’ functional states that reach out into the world of things and their colors.

functional state

Which functional state?Which functional state?

• “Long-arm” functional states, whose inputs and outputs are outside the brain, capture intentional content but not qualitative content.

• Brain-internal functional states might capture qualitative content but not intentional content: the same brain-internal functional state may represent different things.

• Either way, qualia can’t be reduced to intentional states: “what it’s like” to see red can’t be reduced to representing red.

• But could qualia be brain-internal functional states?

Intentional ContentIntentional Content Qualitative ContentQualitative Contentfunctional state

PhysicalismPhysicalism

• Physicalism: thesis that everything is physical or supervenes on the physical

• Block is not arguing that there could be a case like this—which would show that physicalism was false.

I see a red blob.

I see a red blob.

I see a red blob.

I see a red blob.

real person zombie twin

PhysicalismPhysicalism

• Block would like to hold that qualia supervene upon brain states

• But worries that his qualia realism may stick us with zombies—beings that are like us in cognitive states but totally lacking qualia

Can we block the zombies?Can we block the zombies?

The End

Documents

The Mind-Body Problem