why ultra-externalism goes too far

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Why ultra-externalism goes too far ROBERT KIRK

1. Externalism has it that the content of intentional states depends essen- tially on relations with the world outside the subject’s skin. ‘Ultra- externalism’ extends this approach to the character of perceptual experience: to ‘what it is like’. According to ultra-externalism this character depends entirely on what information is being conveyed, or on the experience’s ‘representational content’. I find ultra-externalism attractive ( I was an ultra-externalist myself once); and clearly it would do useful work if it were sound. But I think it goes too far.

I think that in normal perception nothing else is going on but physical processes which, because of their relations to external things, constitute the acquisition of certain sorts of information (in certain ways: see my 1994a). But in their anxiety to avoid Cartesianism, ultra-externalists have ended up trying to make content (or information) do too much. They have not given sufficient weight to the fact that when you have a perceptual experience, something actually happens inside your head. Of course what happens there would not contribute to a perceptual experience at all unless it were suitably related to things in the world. Representational content does seem necessary for perceptual experience. But as I shall explain, there is a sense in which it is internal processes that fix the character of a perceptual experience.

In 1994b, I described a putative counterexample to ultra-externalism, a sort of chemically pure version of the inverted spectrum idea. To ensure the necessary symmetry I used the detection of just two kinds of coloured light instead of full normal colour vision. Gregory McCulloch is not persuaded.

ANALYSIS 56.2, April 1996, pp. 73-79. 0 Robert Kirk

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In his 1994, he makes two main claims: (a) my argument is ‘weak’; (b) even if he were to be ‘very charitable’ and concede it works for the sort of case I described, I still give ‘no reason at all for supposing that its conclusion generalizes’ (to the case of normal colour vision, for example: McCulloch 1994: 265). In the next section I will reply to (a) and (b): I don’t think he has dented my original argument. In $ 3 I will briefly counterattack. (McCulloch does not endorse ultra-externalism quite generally. However, he is ‘sympathetic’ to an important implication: that the character of visual experience is entirely determined by its representational content ( 1994: 265) . )

2. (a) My putative counterexample had me blind from birth and fitted with a pair of primitive light detectors, one for red light, one for green. The wires from the two detectors were each connected to a different part of my brain. Eventually I found I had one kind of experience when faced with a source of red light, and another when faced with green light. With practice I became able reliably to use the device to detect sources of red and green light such as pedestrian crossing lights, car brake lights, and so on. So (it appeared) there was something it was like for me to perceive the red light, and something else it was like for me to perceive the green light. However, it had been only by an arbitrary choice that the two detectors were connected to my brain as they were, rather than the other way round. So the character of the experience caused by the output from the red detector was not necessarily linked with red light, hence not necessarily linked with information or representational content about red light. In developing the argument I showed why various behaviourist and other objections would not work. McCulloch finds that my ‘rebuttals of various replies carry conviction’ (1994: 266 - here I will assume that behaviourism is to be rejected). But he still claims the argument is weak.

His main complaint is that I do not show that ‘the experiences delivered by the device do indeed have representational content, and are not analogues of mere feelings or sensations’ (267) . Now, I did briefly offer reasons to think the experiences in question have representational content (Kirk 1994b: 296,30lff.), and will back them up shortly. But I am not both- ered if those experiences are also in some sense analogues of feelings or sensations. For I maintain that internal physical processes are by themselves sufficient for experiences subjectively indistinguishable from perceptual ones (see $ 3 ) . If that is right they might for that reason be said to be ‘anal- ogous to’ feeling or sensation; in which case it is no objection to say so.

The reason for supposing the experiences in the story have representational content is that they do not seem significantly different from those of other sense-modalities. Notably they are appropriately linked with certain

WHY ULTRA-EXTERNALISM GOES TOO FAR 75

kinds of external things. The red-light sensor yields one kind of experience, the green-light sensor another; and since I can co-ordinate the deliverances of hearing, touch, and other senses with those of the device, I can learn things about the different sources of red and green light. (At !east I can do so provided there are other differences between them than merely that they emit the two different kinds of light. In a world where the only such sources were, say, Christmas tree lights, my ability to discriminate between red and green ones would not be much use. But in the world as it is, especially with things like pedestrian crossing-lights, there would be plenty to learn.) Hence when I encounter a source of red (green) light, it seems I am in a state which (normally or typically, for me) has the representational content that something red (green) is in the vicinity. (There is room for debate over whether I should have precisely our actual concepts of red and green: see Kirk 1994b: 295, 304.)

However, McCulloch thinks the onus is still on me to justify the claim that the experiences in question have representational content. That is puzzling. There is after all nothing unusual about the reasoning just sketched. Nor does it seem that ultra-externalists could object to it. Their view is an extension of externalism, so they must agree that representational content depends on relations between a suitable subject and the outside world. The relations just described seem relevantly like those of cases of normal human perception; and it is at any rate natural to assume that all normal human perception involves experiences with representational content (see below).

Let us modify the example slightly. Suppose there is a naturally evolved population which has, instead of normal vision, only the limited sensitivity to two kinds of light that the device affords me in the original story, Each of them, growing up, acquires a network of different beliefs, capacities, expectations, and so on, linked with the two types of light source - just as in the artificial case. Thinking in terms of such a population helps to make clear that the limited visual sense in the story could conceivably be possessed by a natural species. If so, there seems no reason to suppose it is significantly different from the ones we are more familiar with. In nature there is a vast range of species whose types of perception are impoverished compared with ours, so we can hardly rule out a priori something like the present possibility being actualized somewhere or other. But if there were such people, how could the perceptual experiences involved in their red- and-green-detection fail to have ‘representational content’? Whatever tests we might think up for probing the perceptual powers of aliens, including investigation of the insides of their heads, these people would pass them.

Yet McCulloch has to maintain that these people’s perceptual experiences lack representational content, otherwise the counterexample

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succeeds. He suggests that what is going on is a process where a certain kind of sensation just happens to convey information, and compares being stung by nettles. That might inform me of the presence of nettles, given context and background information: it would be a case of ‘gathering that there are nettles around by being stung’ ( 2 6 7 ) . And I agree that one cannot sensibly conclude that the sensation of being stung therefore has ‘that there are nettles around’ as part of its representational content. But I suggest that is because there are several obvious ways in which the sensation of being stung doesn’t fit into the pattern of ordinary cases of perception; not because absolutely nothing of that sort could occupy the role of bearer of representational content. In strong contrast the experiences of my red-and- green perceivers fit into the rest of their lives in ways not significantly different from those in which our normal perceptual experiences fit into our lives. So far, then, McCulloch has given us no reason to suppose that the red-and-green perceivers’ experiences lack representational content. That is my reply to his first objection (a).

(b) Or rather, it is my reply apart from what there is to be said about his second objection. This is that even if I have refuted ultra-externalism for the special case in the example, I have ‘done nothing to show that [the case thus made] generalizes’ (269). What I have just been saying may help to explain why I thought I had done enough in that direction. For if the last paragraphs are correct, what goes for that special kind of perception goes for perception in general. Of course I did not assume that normal human perception would provide instances of transposition: the whole point of the artificial example was to ensure that there was - contingently - a kind of symmetry which probably doesn’t exist in normal cases. But it does seem that the arguments supporting this counterexample, if sound, are enough to refute ultra-externalism across the board. However, McCulloch seems to think that not all kinds of perception involve experiences with representational content: it is only on that remarkable assumption that he can press the present objection.

But I know of no plausible principle for marking off sense-modalities which supposedly do not involve such content from those which do. Surely it is the very fact that they have representational content that marks off all kinds of perception from sensation, ordinarily understood. McCulloch himself says that ‘one conveys what it is like to be in such a state [seeing that there are nettles over there] by stating its representational content as specified by the that-clause’ (265) . By that standard all our senses without exception involve experiences with representational content. We can see that the flower is blue, hear that the cat is outside, feel that the cloth is soft, taste that the wine is sweet, and smell that there is fresh coffee around. And since the special kind of sensory system possessed by the red-and-green-


perceivers enables them to discriminate on the basis of their special experiences, they too can describe their experiences as representing, for example, that there is a red (green) light source ahead. So I think we have the best possible reasons for holding that ‘the experiences delivered by the device do indeed have representational content’. Nor has McCulloch provided any good reason to deny it.

(Nor, of course, is it open to him to reply that if these experiences do have content, their different contents are sufficient to fix what they are like. For the contents come from relations between them and external light- sources, such as crossing-lights, while the role of such light-sources in the world depends - or could perfectly well depend - on conventions; so the relations between such things and appropriate behaviour have to be learned. And clearly, which experience is linked with which external features can be learned only if the experiences have character prior to acquiring their respective contents (see Kirk 1994b: 298f., 304). Although the two experiences are different, each is apt for conveying either of the two sorts of content. So their representational content does not fix their characters.)

If that is right, it is not true that in all possible cases the representational content of perceptual experiences fixes what the experience is like. Where there is symmetry of the sort envisaged, experiences with different characters could carry the same representational content. (That is consistent with saying, as I believe, that if in fact the members of a community normally have experiences with the same character in the same circumstances, then a verbal specification of the content of the experience entails it has that particular character: see Kirk 1994a: 40-46; 1994b: 307.)

3 . Now for the counterattack. Ultra-externalists do not of course deny that there are hallucinations. But they say they derive their character from their content, which in turn depends on relations with the outside world. I cannot hallucinate a flash of light, for example, unless I am suitably related to flashes of light. But can ultra-externalists also concede that a person not suitably related to flashes of light could still have an experience with the same character as that of seeing a flash of light? We can easily see that they cannot - but that leaves them in a peculiar metaphysical position.

If they were to concede that possibility, they could not consistently deny the possibility of the red-green perceivers. Such cases are possible if the following conditions are satisfied: (i) there are subjects with a sensory modality whose sensitivity to features of the world has the symmetry exemplified in the story; (ii) internal processes are sufficient to fix the character of an experience subjectively indistinguishable from a perceptual one. (i) seems purely contingent; the philosophical issue concerns (ii). So ultra-

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externalists must maintain not only that representational content fixes the character of perceptual experiences in all possible cases, but that processes inside the subject cannot possibly be sufficient for experiences subjectively indistinguishable from perceptual ones.

Consider two comnion phensmena, phosphenes and tinnitus. Neither involves actually perceiving things; but events subjectively indistinguishable from them could well be components of perceptual experiences: experiencers of phosphenes sometimes find they do not know whether they have really seen a light. These phenomena are apt for conveying representational content even though they don’t normally do so. Now, ultra- externalists will say that if these phenomena involve experiences indistinguishable from those of sight and hearing, that is because they have the right content. But here is the difficulty. Phosphenes and tinnitus are often caused entirely by events inside the subject’s head. How can those relations with the world which are necessary to ensure that an experience has representational content possibly make the required difference? If purely internal events can cause hallucinations, why can’t they cause content- lacking experiences that are subjectively like hallucinations?

Clearly, ultra-externalists have to deny a priori the very possibility that congenitally blind people may have phosphenes. Such people, or at any rate communities of such people, lack the necessary relations with the world for their putative experiences to have suitable contents. Yet it is at least hard to see how those possibilities could be denied a priori. There is certainly no a priori reason why processes in the brain of a congenitally blind person should not happen to match those in the brain of someone with (whatever ultra-externalists regard as) sufficient visual capacity to qualify for having phosphenes. (They might result from surgical interven- tion, or even from worms wriggling.) Call those physical processes P. Ultra- externalists have to maintain that although P would have been sufficient for a phosphene given the right relations (R) between subject and world, P would not be sufficient for anything like a phosphene in the absence of R.

But how could mere relations with the outside world make a difference when P is not sufficient by itself? How could those relations get in on the act? P may be caused purely internally, whether or not R holds as well; yet it is not as if R s holding required there to be any actual flashes of light when P occurs. The problem becomes especially vivid when we reflect that the relevant content-giving relations need not be with things that still exist. Someone who was once able to see actual flashes of light may now be blind; but externalists will not deny that they may still have hallucinations of flashes of light. It is unproblematic that in order for the hallucination to be of light, the subject must have been suitably related to light. What is problematic is the claim that such relations are necessary in order to have


an experience like that of such a hallucination. I suggest we have no model on which this claim can be understood.

Two models seem possibly relevant: that of relational (or extrinsic) properties, such as having been made in England; and that of a system: something whose properties depend on the relations among its components. Now, an experience’s representational content is certainly a relational property; but the present difficulty is to understand how the historical origins of P can possibly have effects on what happens now, given that I? is exactly like what would have been produced by the relevant past events. It seems like saying that two exactly similar cars could not behave similarly because one was made in England and the other wasn’t. Nor does the model of a system help: after all, the other components of a system do have to exist, while the events which conferred representational content may belong to the remote past. So far, then, it seems that ultra- externalism involves a deep metaphysical mystery.l

University of Nottingbam Nottingbam NG7 2RD

Robert. [email protected]

References Kirk, R. 1994a. Raw Feeling: a philosophical account of the essence of consciousness.

Kirk, R. 1994b. The trouble with ultra-externalism. Proceedings of the Aristotelian

McCulloch, G. 1994. Not much trouble for ultra-externalism. Analysis 54: 265-69.

Oxford: Clarendon Press.

Society 94: 293-307.

I have benefited from many discussions with Gregory McCulloch, Duncan McFar- land, and Patrick Smith.

why ultra-externalism goes too far

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