Need for Third Condition Discussion of the NozickDretske Analysis

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Page 1 of 7 Need for third condition. Discussion of the Nozick#Dretske analysis

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College London; date: 16 December 2012

Knowledge and the State of Nature: An Essay in ConceptualSynthesisEdward Craig

Print publication date: 1999Print ISBN-13: 9780198238799Published to Oxford Scholarship Online: Nov-03DOI: 10.1093/0198238797.001.0001

Need for third condition. Discussion of the NozickDretske analysis

Edward Craig

DOI: 10.1093/0198238797.003.0003

Abstract and Keywords

The author contends that in the state of nature we need some detectableproperty of informants that correlates well with their being right about p.This yields a twofold criticism of Robert Nozick's truthtracking analysis ofknowledge. First, it is not necessary that the informant be a good trackerin all close possible worlds, merely those that are open possibilities, thosethe inquirer cannot rule out as being nonactual. Second, the inquirer cannot

set herself directly to pick out a good tracker of p, so Nozick's favouredknowledgeconferring property lacks the necessary epistemic accessibility.

Keywords: epistemic accessibility, Nozick, possibility, possible worlds, truthtrackinganalysis

It is the third clause of the analysis, I need hardly say, which has caused all

the trouble. Is it that the belief has to be based on good reasons, or that it

has to have the right causal ancestry, or that it must have been acquired by

a reliable method, or that it must, in Nozick's felicitous term, track the fact

that is its object? All these, and probably more, are on the market, some in

a number of models. It has even been urged that we decline them all, anddefine knowledge as true belief, with no adornments. Our next question must

be: does the concept that we are constructing, the one whose sole purpose

is to act as a marker for approved sources of information, call for anything

more than that, and if so, what?
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First impressions suggest a short way with this question: no further

conditions are needed. Why should we want more of a potential informant

than that his views on the point at issue should be true, and at least

confident enough for him to be prepared to come out with them? Then we

come to hear the truth, which was what we wanted. But this overlooks acrucial point. It is not just that we are looking for an informant who will tell

us the truth aboutp; we also have to be able to pick him out, distinguish himfrom others to whom we would be less well advised to listen. How is that to

be done? Well, it will be easy enough to find out what he believes aboutp;and if we ourselves knew whetherpthat would suffice to tell us whether hehas a true belief. But ex hypothesiwe do not know whetherpwe are in theposition of inquirers, not of examiners (to borrow Bernard Williams's way of

putting it); the informant is to be our means of access to that knowledge,

and if we already had it, we would not be inquiring. Obviously, we have to

detect the right informant without benefit of prior knowledge. So we needsome detectable propertywhich means detectable to persons to whom it is

not yet detectable whetherpwhich correlates well with being right aboutp; a property, in other words, such that if the informant possesses it he is (atleast) very likely to have (p. 19 ) a true belief on that matter. The emergence

of this requirement gives us, as it turns out, quite a lot to work with.

Let us at this stage set up a target for ourselves, so to speak. Nozick 1has

suggested that a knower must, besides having a true belief, satisfy two

further conditions:

(i) Ifpwere not true, he wouldn't believe thatp.(ii) Ifpwere true (but under circumstances differing slightly fromthose actually obtaining) he would believe thatp.

In discussing these conditions, I shall make free use of the now popular

vocabulary of possible worlds (without supposing it to be anything more

than a linguistic convenience); and I shall follow David Lewis 2in saying that

(i) and (ii), as counterfactual statements, are true if and only if in possible

worlds close to the actual world, ifpis false the subject does not believethatp,and if it is true he does believe it. I shall ask whether the practical

explication we are engaged in might not lead to just these two conditions.

An immediate reaction is to ask Why should it? Why should our inquirer

be interested in what is the case in possible worlds? After all, he wants to

be told the truth in this world, the actual world, so whence the interest in

other, and merely possible, worlds, however close they may be to this

one? Either Nozick's tracking condition is not what we are looking for, or


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Lewis' semantics for counterfactuals in terms of possible worlds have to be

dropped. But this is too quick: there is a line of thought which shows that the

inquirer cannot help being interested in the contents of possible worlds as

well as those of the actual.

We have to remember that the inquirer's knowledge of the actual world

is bound to be highly incomplete. It is not only that he doesn't yet know

whetherp; there will be all sorts of things about himself, the environmentand the potential informant of which he is ignorant. There are, in other

words, enormously many propositions such that he does not know whetherAor notA,whether Bor notB,and so on. So if we think of a world as definedby the totality of what is true in it, there are indefinitely many different

possible worlds any one of which, so far as he knows, might be the actual

world. His concern with getting the right information in the actual world (p.

20 ) will therefore lead him to hope for an informant who will give him thetruth aboutpwhichever of all these possibilities is realised. Which is to say,if you like the jargon, that he wants an informant who will give him the right

answer in a range of possible worlds.

Is it possible that we are not being quite rigorous enough here, and claiming

more than in fact follows from the inquirer's position? The reply can be made

that he is only interested in the actual worldit is just that he doesn't know,

out of all those possible worlds, which one it is. What I need, he might say,

is for the informant to be right in whichever of these possible worlds is the

actual one; the rest can go hangI shall have my true belief.

I doubt whether we can accept that, however. The trouble is that it leads to

no strategy on the part of the inquirer. Imagine someone about to go out,

and wishing to stay dry, but not knowing whether it will be raining or not, so

that he faces one possible world in which it will, and one in which it won't.

Can he say I only want to keep dry in the actual world; I'm not bothered

about whether I would have kept dry in whichever of those worlds turns out

to be merely possible? He can sayit, and in a sense no doubt it is true. Butif he proposes to do something about it he will either have to guess which

possibility will be realised or take such action as will work in either case,

even though that means planning for at least one eventuality which will turnout to have been merely possible. And the same applies to our inquirer: he

must either guess which of the possible worlds he is actually in, or he must

adopt a strategy which works in many merely possible worlds as well as the

actual one.


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Some may now have got the impression that I am about to award a prize

to Professor Nozick; for haven't we said, in effect, that the search for the

desired informant will naturally become a search for someone who is

precisely a good tracker ofp,someone whose belief as to whetherpis

true in all close possible worlds? But I am not, for two main reasons. For onething, Nozick does not select the right range of possible worlds, if by that

we mean one that coincides with the range of interest of the inquirer. For

another, Nozick's tracking condition doesn't reflect the epistemic demands

that the inquirer is bound to make. I shall return to the second point later,

having dealt in some detail with the first.

The first point, then, is that Nozick's range of possible worlds is not the one

which will concern the inquirer; it overlaps with (p. 21 ) it, of course, but

it is wider. And just this extra width causes trouble for his account, seen

(in the way he surely meant it) as an attempt in traditional style to matchan intension to the intuitive extension of know. The practically explicated

concept, on the other hand, picks the right range of possible worlds, and

illuminates the reason for doing so. Here we see it scoring its first points

against a prestigious attempt at an analysis of the more familiar kind.

Nozick recommends assessing his two counterfactuals by reference to what

is the case in all close possible worlds. Fortunately it is not necessary for

our purposes to specify exactly what close means here. Roughly speaking,

two worlds are said to be close to each other if they differ only slightly,

distant if they differ radically, and this is accurate enough for the point I

now wish to make, which is that our inquirer will not be interested in allclose possible worlds, but only in those that he cannot rule out as being

merely possible, or nonactual. Suppose he is considering the credentials of

a potential informant whom he can see to be wearing a red shirt. There is

a close possible world (and it surely is close, if the concept of closeness is

to be capable of any work whatever) in which that same person is wearing

a blue shirt; but since the inquirer will be perfectly satisfied that this world,

although both possible and close, is not the actual world, he will have no

interest in it. It is of no concern to him whether the potential informant would

hold a true belief on the question at issue were he wearing a blue shirt he

already knows that he isn't.

(Here we should watch out for a point which could cause confusion. If you

really thought that I would quite likely be wrong aboutpwere I wearing ablue shirt, you would be doubtful about employing me as informant even

if you could see that I am wearing a red one. But that is not be because


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you are taking the blue shirt world into account as one in which, for your

purposes, I need to be right. Rather it happens because, your beliefs about

the effect that the colour of one's shirt has on capacity as an informant being

what they are, for almost any value ofpthe belief that I wouldn't be good on

pwere I wearing a blue shirt will make you wonder how then I can be goodonpwhen wearing a red one.)

If we use the expression open possibility to mean a possibility which so

far as the inquirer knows might be actual, we may put the point more

generally in these terms: the inquirer will want the informant to be a good

tracker ofpin worlds that are both close (p. 22 ) and open possibilities forhim, the inquirer. This will be a narrower class of possible worlds than that

which Nozick uses for the assessment of his counterfactual conditions. The

possibility therefore arises that Nozick's analysis will rule out some cases of

(putative) knowledge where an analysis more closely tied to the situation ofthe inquirer would allow them. This would happen if tracking held in all the

possible worlds which the inquirer will have an interest in, but failed for at

least one of the wider class of possible worlds which Nozick would have us

take into account.

With this thought in mind, let us look at a case which causes Nozick a good

deal of trouble: the case of the Great Bank Robbery. 3Jesse James, the

reader will recall, is riding away from the scene of the crime with his scarf

tied round his face just below the eyes in the approved manner. The mask

slips, and a bystander, who has studied the wanted posters, recognises

him. The bystander now knows, surely, that it was James who robbed thebank. But Nozick has a problem: there is a possible world, and a close one,

in which James' mask didn't slip, or didn't slip until he was already past the

bystander; and in that world the bystander wouldn't believe that James

robbed the bank, although it would still be true that he did. So Nozick's

condition (4)the second of the two counterfactuals is not satisfied, and

he is threatened with having to say that the bystander doesn't know that it

was James, even though the mask did slip. So his analysis looks like ruling

out something which is as good a case of knowledge as one could wish for.

In the face of this problem Nozick resorts to fudging. He recalls his previousstipulation that the method by which the knowledge is acquired be held

constant, so that close possible worlds in which a different method would

be used to arrive at the belief thatpfrom that used in actuality are not tofigure in the assessment of the counterfactuals. And he then implies that,

had James mask not slipped, the bystander would have been employing


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a different method, an implication which violates the distinction between

the method and the evidence obtained by the use of it (as Graeme Forbes4has put it). A natural response to the case of the Great Bank Robbery, I

believe, is that such a manuvre ought to be unnecessary; for what would

have happened if the mask had not slipped is wholly (p. 23 ) irrelevant tothe question of the bystander's knowledge. The right approach to the matter

would never have let it come anywhere near the picturethen no fine and

dubious distinctions would have been necessary to expunge it again. But

the view from the standpoint of the inquirer has the properties we want

here. Until he is satisfied that the mask did indeed slip, the sheriff will not

be interested in the bystander's identification; once he is satisfied that it

slipped, possible worlds in which it did not slip are deletedthey play no

part, not even implicitly, in his judgement as to whether the bystander knows

that it was James.

The second point about Nozick's analysis is this: What I have said so far

may suggest that the difference between his tracking and the conditions

(in addition to true belief) which our inquirer will want to impose on his

sources of information is fairly minimal: the inquirer will be happy with

counterfactuals of Nozickian stamp, assessed laLewishe will simplyconsider a narrower, more contextdependent, range of possible worlds. If so

I apologise, because the suggestion is seriously misleading. Good tracking of

the fact thatpcannot be the property that the inquirer is looking for; at bestit may be something that coincides with it.

I said earlier that Nozick's tracking condition does not reflect the epistemicdemands that the inquirer is bound to make. The inquirer has to pick out

the right informant, and no doubt it would help, even if only as a first

approximation, to pick out a good tracker of the factp.But he cannotset himself directly to pick out such a person, because the truth of a

counterfactual is not epistemically primary in the sense that that would

require. We don't have equipment that allows us to spot people who satisfy

Nozick's counterfactuals as such. We can tell of some people that they do,

and we do it not directly but by noticing something about them, perhaps the

way in which they came to believe thatp,which can be seen to correlate

with satisfying the counterfactuals. What we ought to be looking for, at leastin the first instance, is some such epistemically more accessible property.

Notes:

(1) R. Nozick, (2), pp. 1728. See also F. Dretske.


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(2) D. K. Lewis.

(3) R. Nozick, (2), p. 193.

(4) G. Forbes, pp. 478.

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Need for Third Condition Discussion of the NozickDretske Analysis