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Experience and Reason in Perception
Published online by Cambridge University Press: 08 January 2010
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The question I am interested in is this. What exactly is the role of conscious experience in the acquisition of knowledge on the basis of perception? The problem here, as I see it, is to solve simultaneously for the nature of this experience, and its role in acquiring and sustaining the relevant beliefs, in such a way as to vindicate what I regard as an undeniable datum, that perception is a basic source of knowledge about the mind-independent world, in a sense of ‘basic’ which is also to be elucidated. I shall sketch the way in which I think that this should be done. In section I, I argue that perceptual experiences must provide reasons for empirical beliefs. In section II, I explain how they do so. My thesis is that a correct account of the sense in which perceptual experiences are experiences of mind-independent things is itself an account of the way in which they provide peculiarly basic reasons for beliefs about the world around the perceiver.
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References
1 This claim is a crucial component of McDowell's, J. position in his Mind and World (Cambridge, MA: Harvard University Press, 1994)Google Scholar. Indeed, the argument I offer in support of it is my own extended development of his very suggestive comments on the matter (see especially Lecture I). Both mind-independence and spatiality are crucial to the claim. Arithmetical thought, for example, even though its subject matter may correctly be conceived as mind-independent, is clearly a different issue. Conversely, I am concerned with our knowledge of the empirical world in a sense in which this is incompatible with any attempted idealist understanding of spatial particulars as, ultimately, mind-dependent. See Foster, J., The Case for Idealism (London: Routledge, 1982)Google Scholar, chapter 5, for a development of this idealist alternative. To avoid undue repetition in what follows, though, I shall often use just one of the two adjectives as shorthand for the pair.
2 McDowell, , Mind and World, pp. 15ff.Google Scholar
3 See Eilan, N., ‘Self-Consciousness and Experience’ (D.Phil, Thesis, Oxford University, 1988)Google Scholar, for a sustained discussion of this kind of claim.
4 The argument which I am about to give is my development of Strawson's, P. F. famous discussion of these matters in his Individuals (London: Methuen, 1959)CrossRefGoogle Scholar, chapter 1, part I. I draw heavily upon N. Eilan, ‘Self- Consciousness’, chapter 5, in which she also acknowledges the importance of conversations with Adrian Moore.
5 See Evans, G., The Varieties of Reference (Oxford: Clarendon Press, 1982)Google Scholar, chapter 7; Gordon, R., ‘Simulation Without Introspection or Inference from Me to You’, in Mental Simulation, ed. Davies, M. and Stone, T. (Oxford: Blackwell, 1995), p. 60Google Scholar; and Roessler, J., ‘Self-Knowledge and Belief’ (D.Phil. Thesis, Oxford University, 1996)Google Scholar, chapter 2, for discussion of this so-called ‘ascent routine’, and its status as a source of knowledge.
6 See Evans, , The Varieties, pp. 104ffGoogle Scholar., and Geach, P., Mental Acts (Bristol: Thoemmes Press, 1992), pp. 53ffGoogle Scholar., for introduction and elucidation of this notion of a person's Idea of an object.
7 The underlying equivalence here can be demonstrated as follows. Suppose that S is a person, p a proposition, and Ks the conjunction of every proposition which S knows. It is epistemically possible for S that p ⇔ it is logically possible that [Ks & p] ⇔ {Ks, p} is consistent ⇔ ‘Ks, therefore not-p’ is invalid ⇔ S cannot argue validly from what he actually knows to not-p ⇔ S is not in a position knowledgeably to rule out that p.
8 It may be objected at this point that the epistemic possibility of multiple satisfaction can be ruled out if S's descriptive Idea is of the following form: ‘The unique G’. This is correct; but, in that case, reference failure due to the emptiness of this description is an epistemic possibility. For, again, S cannot knowledgeably rule out the possibility of massive reduplication with respect to G. So an appropriately adjusted version of my argument goes through. Note, also, that the argument does nothing to undermine the possibility of thought about spatial particulars by what might be called impure description, in which reference is secured, in part, by an embedded demonstrative, as in, for example, ‘The red ball under that table’.
9 This step in the argument requires further defence too. For it might be thought that either names or certain descriptions embedding indexicals provide an equally acceptable alternative to pure descriptions, in a way which finesses my appeal to essentially experiential perceptual demonstratives. What is wrong, for example, with the following Ideas: ‘Frege’; and ‘The ball in front of me’? I cannot respond in detail to these points here. My claim in each case, though, is that, insofar as the Ideas in question are immune to my objection from the possibility of massive reduplication, a complete account of what is involved in understanding them cannot avoid reference to perceptual experience. In the case of names, this is either a result of the connection between the subject's understanding of the name and his possession of a recognitional capacity for its bearer (if he is a Producer, in Evans’ sense), or of the connection between his understanding of the name and the various experiences involved in his being informed about its bearer in testimony of some kind (if he is a Consumer). See Evans, The Varieties, chapter 11, for this distinction between Producers and Consumers in a name-using practice, and an outline of the account of proper names upon which my reply here draws. In the second case, experience comes in in the crucial role of demonstrative reference to physical things other than himself both in the subject's grasp of the spatial concepts figuring in such descriptive-indexical Ideas, and in his grasp of the first person pronoun itself. These issues require extended discussion though. A further source of objection might be the claim that experience is essential to demonstrative reference. After all, a blindsighted patient apparently refers to a particular object in his blind field when encouraged to point to it. Yet he has no experience of it. Here I simply insist that he does not understand any demonstrative thought he may appear to others to be having. For he does not know which object is in question. See Weiskrantz, L., Blind Sight: A Case Study and Implications (Oxford: Clarendon Press, 1986)Google Scholar for a comprehensive study of such cases.
10 Peacocke, C., Sense and Content (Oxford: Clarendon Press, 1983), pp. 20ff.Google Scholar
11 See Peacocke, C., ‘The Limits of Intelligibility: A Post-Verificationist Proposal’, Philosophical Review 97, (1988)CrossRefGoogle Scholar, for characterization and discussion of such arguments.
12 Burge, T., ‘Our Entitlement to Self-Knowledge’, Proceedings of the Aristotelian Society 96 (1996)CrossRefGoogle Scholar; and Peacocke, C., ‘Entitlement, Self-Knowledge and Conceptual Redeployment’, Proceedings of the Aristotelian Society 96 (1996).Google Scholar
13 See Thought and Object, ed. Woodfield, A., (Oxford: Clarendon Press, 1982)Google Scholar; and Subject, Thought and Context ed. Pettit, P. and McDowell, J. (Oxford: Clarendon Press, 1986), for a good orientation.Google Scholar
14 I take it that this is one way of filling out the suggestion in section 3 of the introduction to Subject, Thought and Context, ed. Pettit and McDowell, of a more radical response than Putnam's own ‘composite’ account to the original discussion of these matters, in Putnam, H., ‘The Meaning of “Meaning‘”, in Mind, Language and Reality (Cambridge: Cambridge University Press, 1975)CrossRefGoogle Scholar. My sketch of this development owes a great deal to their treatment, and to other work by McDowell too.
15 Putnam, ‘ The Meaning of “Meaning”.‘
16 Evans, The Varieties, chapter 8· Of course, the precise nature of such capacities is a very difficult matter. Their possession presumably requires some sensitivity to the fact that any putative re-identification of the kind in question is defeasible by scientific investigation; and, relatedly, the ability to keep track of samples over certain changes in appearance, along, perhaps, with a rough idea of what types of change are compatible with continued instantiation of the kind.
17 There is of course a debate at this point about precisely what the relations of priority are, if any, between identifications, of various kinds, of objects and their locations in this basic case, in which the things and places in question are displayed in experience. See Strawson, Individuals, chapter 1; Wiggins, D., ‘The Individuation of Things and Places (I)’, Proceedings of the Aristotelian Society, Sup. Vol. 37 (1963)Google Scholar; Woods, M., ‘The Individuation of Things and Places (II)’, Proceedings of the Aristotelian Society, Sup. Vol. 37 (1963)Google Scholar; Evans, The Varieties, chapter 6; and Campbell, J., ‘The Role of Physical Objects in Spatial Thinking’, in Spatial Representation, ed. Eilan, N., McCarthy, R. and Brewer, B. (Oxford: Blackwell, 1993)Google Scholar. I am confident, though, that what I have to say here is independent of the detailed differences of view on these matters.
18 What if the thing in question is a part of the subject's body? Things get very complicated in this case. First, bodily awareness is likely to be involved in a peculiar way. Although I am sympathetic to the idea that perceptual systems are normally both exteroceptive and proprioceptive, as elaborated by Gibson, J. J. in his The Ecological Approach to Visual Perception (Boston: Houghton Mifflin, 1979)Google Scholar, the object of exteroception is not normally itself an object of proprioception, as it is in this case. Second, and relatedly, a person's body-parts are normally experienced as his own. See Brewer, B., ‘Bodily Awareness and the Self’, in The Body and the Self, ed. Bermudez, J., Marcel, A., and Eilan, N. (Cambridge, MA: MIT Press, 1995)Google Scholar, for a discussion of these two points and their interrelations. Nevertheless, if the body-part in question is anaesthetized and experienced only as ‘that hand’, as opposed to ‘my hand’, then the condition in the text applies. At least, in cases in which it is the hand's displayed location which informs the subject's perceptual reference to that particular hand, then he must grasp that that location might have been displayed as differently located on some egocentric reference frame.
19 J. Campbell, ‘Spatial Decentring and Other Minds’, forthcoming. I am also indebted at this point to Naomi Eilan for some very helpful suggestions.
20 This is of course an application to the current case of G. Evans’ ‘Generality Constraint’. See his The Varieties, esp. Chapter 4.3. The requirement is derived from Strawson, Individuals, esp. Chapter 3.
21 I do not mean to claim here that the subject must explicitly operate with a theory about the way in which spatial appearances vary with changes in his point of view. Rather, he has the potential, at least, to trip to and fro between a fixed relational conception of where a certain thing is relative to him, and both his actual, immersed monadic impression of its location, and various non-actual possible alternatives to it had he perceived that thing from a different point of view, simulated in imagination. Although his skill in this regard need not be at all well developed, this must at least be possible for him, in sense that his relational egocentric spatial Ideas are the essential ground for whatever such imaginative routines are actually engaged.
22 The common structure here is this. Suppose that the contribution of experience to securing determinate reference to mind-independent particulars in the cases under consideration is its displaying the relevant object's characteristic φ. In the central cases I have been discussing, φ is spatial location; equally, it might be timbre, for example, in auditory reference to a particular member of an unseen wind quintet. My development of Strawson's argument in section I implies, on the one hand, that this contribution is to make available to the perceiver an essentially experiential demonstrative Idea of the object in question, such as ‘thatφ thing’. The mind-independent reference of this Idea, on the other hand, requires that his grasp of the characteristic φ in question should not be exhausted by the way in which it is actually presented in his current experience. The apparent tension between the two is to be resolved by the subject's grasp of the actual experiential appearance of φ, from immersed within his present perspective and suspending any reflection upon it or its contribution to his experience, as the joint upshot of the mind-independent φ of the object in question and the relevant features of his particular perceptual perspective upon it. As will become clear, it is precisely this understanding which I think constitutes his prima facie reason to endorse the demonstrative content in question in belief.