Wednesday, 16 March 2011

Short extract from McDowell Perception as a Capacity for Knowledge

I’ve been reading John McDowell’s recent paper ‘Perception as a Capacity for Knowledge’ which is largely a critique of Burge’s view of how perceptual states warrant perceptual beliefs. McDowell, plausibly, argues that it cannot sustain perceptual knowledge. Roughly, its accommodation of fallibility undermines the ability of perception to underwrite knowledge when all goes well. So a key argument in McDowell’s paper consists in outlining a different approach. This passage is by no means the only interesting aspect of the paper but it seems to me to be key.
9. I think this reflects a mistake about the concept of fallibility. And I do not believe the mistake is special to Burge. On the contrary, it is pervasive in epistemology. It is typical for discussions of the epistemology of perceptual knowledge to begin with the assumption I have found in Burge, that experience itself cannot provide better than in-conclusive warrant for belief. Often this is quickly taken for granted. But if a ground is offered, it is typically something on the lines of Burge's appeal to the fallibility of all our perceptual capacities.
Burge thinks a Sellarsian epistemology for perceptual knowledge as enjoyed by rational subjects falls into an unacceptable intellectualism. I have suggested this reflects a blind spot for a conception of perceptual warrant that Sellars enables us to frame. And I think the way Burge exploits considerations about fallibility, to underwrite the view about perceptual warrant that is essential to his accusation against Sellars, is exemplary of a widespread tendency in philosophical thinking about perception as a capacity for knowledge. It should be instructive to think this through.
Fallibility is a property of capacities, or perhaps of cognitive subjects as possessors of capacities. If a capacity is fallible, or if, to speak in chat other way, anyone who has it is fallible in respect of it, that means that there can be exercises of the capacity in which its possessor does not do what the capacity is specified as a capacity to do.
That account of fallibility is completely abstract. It puts no restrictions on what a fallible capacity can be a capacity to do. Certainly Burge is right that all our perceptual capacities are fallible. But we can acknowledge that a capacity is fallible with-out precluding ourselves from saying that what it is a capacity to do is this: to get into states that consist in having a certain feature of the objective environment perceptually present to one's self-consciously rational awareness. If that is what a capacity is a capacity to do, that is what one does in a non-defective exercise of it. And I have urged that if a perceptual state can be described in those terms, there is no possibility, compatibly with a subject's being in such a state, that things are not as she would believe them to be in the beliefs that the stare would warrant. When we acknowledge that a capacity is fallible, we acknowledge that there can be exercises of it that are defective, in that they fail to be cases of what the capacity is specified as a capacity to do. That does not preclude us from holding that in non-defective exercises of a perceptual capacity subjects get into perceptual states that provide indefeasible warrant for perceptual beliefs.
For instance, a capacity to tell whether things in one's field of vision are green is a capacity —fallible, by all means—to get into positions in which the greenness of things is visibly there for one, present to one's rationally self-conscious awareness. If something's greenness is visibly there for one, one has conclusive warrant for believing that it is green. One's perceptual state leaves no pos-sibility that it is not green. That the capacity is fallible means that a possessor of it can be fooled, as Burge puts it; for instance, if the light is unsuitable for telling the colours of things, one can rake something's greenness to be visually present to one when the thing is nor green at all. It is wrong to think it follows that even when one is not fooled in an exercise of this capacity, one's position must fall short of having something's greenness visibly present to one, and thereby having an indefeasible warrant for believing the thing to be green. That is just what one's position is in a non-defective exercise of the capacity.
If we follow the etymology of the word, fallibility is a possibility of being deceived. That is an imperfection in cognitive capacities. But the mistake I am pointing out may be easier to recognize if we consider its analogue in application to imperfection in other sorts of capacities. Think of the capacity to sink eight-foot putts. Even the best golfers do not sink all their eight-foot purrs. The idea I am considering is that there cannot be capacities, acknowledged to be fallible, whose non-defective exercises put their possessors in positions in which they have conclusive warrant for beliefs. One might as well think there cannot be a capacity, of course not guaranteed success in every exercise, in whose non-defective exercises a possessor of it actually sinks eight-foot putts.
10. It might seem that this way of dealing with imperfection in capacities cannot have the kind of significance in epistemology that I am suggesting it does.
To say that a perceptual capacity is fallible, or that anyone who has it is fallible in its exercise, is to say that the capacity does not ensure that its possessor is always in a position to discriminate defective exercises from non-defective exercises. If a capacity did ensure that, it would be in principle infallible; through carelessness or insufficient attention, someone might still mistake defective exercises for non-defective exercises, but the capacity itself wot.dd be perfect. But that sort of perfection is surely nor within our reach. That is the point of saying, nor just that we are not guaranteed to be correct in all our perceptual beliefs, but that our perceptual capacities themselves are fallible. It is not just that we are prone to carelessness and inattentiveness, but that no perceptual capacity excludes all possibility of defective exercises such that, however careful or attentive one was, one would not recognize them as defective, at least at the time.
And now it is tempting to argue like this: even if we grant, perhaps temporarily and for the sake of argument, that a non-defective exercise of a perceptual capacity puts one in a state that consists in having some feature of one's environment present to one, being in such a state cannot have the epistemological significance I have been claiming for it; it cannot provide one with indefeasible warrant for a belief that registers the presence of that feature. Perhaps a perceptual state would give one indefeasible warrant for a suitably related belief if one knew that the current exercise of one's perceptual capacity was non-defective. But to accept, as we must, that the capacity is fallible is co accept that defective exercises of it can be indiscriminable, at least at the time, from non-defective exercises. And it can seem to follow that even if the current exercise is not defective, the subject cannot know that it is not defective. It can seem to follow that even on an occasion on which someone is in a perceptual state of the kind I am claiming we can describe in terms of the presence to her of a feature of her environment, her perceptual state is, for all she knows, not of that kind—her current exercise of her perceptual capacity is, for all she knows, defective. So surely she does not know whatever it is about the environment that she takes her perceptual state to enable her to know.
In response to this, we need to emphasize the connection between reason and self-consciousness. A rational perceptual capacity is a capacity not only to know certain kinds of thing about the environment, but, on an occasion on which one knows something of the relevant kind through the exercise of the capacity in question, to know that that is how one knows it. The capacity—of course fallible—to know, on certain occasions, that one's experience is revealing to one that things are a certain way, which is a bit of self-knowledge, is just an aspect of the capacity—of course fallible—to know through experience, on those occasions, that things are that way. It is a single capacity, self-consciously possessed and exercised. A bit of rational perceptual knowledge includes knowledge that it is through perception that one knows whatever it is that one knows about the environment. And we need to avoid that bad inference from the fallibility of the capacity, not only in connection with its guise as a capacity for knowledge about one's environment, but also in connection with its guise as a capacity for self-knowledge. Granted, one can mistake a defective exercise of the capacity for a non-defective exercise. But it does not follow that the capacity cannot be correctly described as a capacity to know things about the environment. And it is just the same point, applied to the same capacity in a different guise, to say this: it does not follow that the capacity cannot be correctly described as a capacity to get into positions in which one knows that it is through one's perceptual state that one knows something about the environment—and so knows that one's perceptual state conclusively war-rants one in the belief in question.
Defective exercises of a perceptual capacity can be indiscriminable from non-defective exercises. It is a mistake to infer that even on an occasion on which the capacity is working perfectly, the current exercise of it is, for all one knows, defective.
Here is Sebastian Rodl's excellent statement of the point:
The argument (from illusion) is: Whenever I seem to know something (on the basis of perceptual. experience), I might have been fooled. Had I been fooled, I would not have known that I was. I would not have been able to tell my situation apart from one in which I am not fooled. This shows that my grounds do not place me in a position to exclude that I am in such a situation. They do not enable me to exclude that I am fooled.—The argument supposes that, had I been fooled, I would have believed the proposition in question on the same grounds on which I believe it now that I am not fooled. This straightforwardly entails that these grounds do not establish the truth of what I believe and therefore do not provide me with knowledge. But when I know something on the ground that, say, I perceive it to be the case, then I would not, had I been fooled, have believed it on this ground, for, had I been fooled, I would not have perceived it to be the case. Hence, when I am not fooled, my grounds exclude that I am fooled: when I perceive how things are, I am not fooled with regard to how they are. One might object that this grants me grounds chat rule out error at the price of making it impossible for me to know whether my belief is based on such grounds. For, when I am fooled, I do not know that I am fooled. So I can never know whether I am not fooled and my beliefs are based on grounds that [establish] their truth, or whether I am fooled and such grounds are unavailable to me. This objection repeats the mistake: from the fact that, when I am fooled, I do not know that I am, it does not follow that, when I am not fooled, I do not know that I am not. When I know that p as I perceive it to be the case, then I know that I perceive that p. Thus I am in a position to distinguish my situation from any possible situation in which I would be fooled, for, in any such situation, I would not perceive that p, while in the given situation I do.' [Rodl, S. (2007) Self-Consciousness, Cambridge, Mass.: Harvard University Press pp 157-8]

McDowell, J. (2011) Perception as a Capacity for Knowledge, Milwaukee: Marquette University Press. pp36-44

I will return to say something about this passage in a couple of days.