1 For a very helpful discussion of this, see Stalnaker, Robert ‘What is it Like to be a Zombie?’ in Conceivability and Possibility, Gendler, T.Z. and Hawthorne, J. eds. (New York: Oxford University Press 2002)Google Scholar.

2 See Chalmers, David The Conscious Mind (New York: Oxford University Press 1996)Google Scholar; Jackson, Frank ‘What Mary Didn't Know,’ Journal of Philosophy 83 (1986) 291–5CrossRefGoogle Scholar; and Kripke, Saul Naming and Necessity (Cambridge, MA: Harvard University Press 1980)Google Scholar.

3 I think another source of confusion, though one that is more difficult to avoid, is talk of a state's functional or causal role. I find it more natural to think of individuals as playing functional or causal roles. It is the electron that has a Charge, and the piece of metal that plays the role of a valve, not some State of the electron or some State of the piece of metal. No doubt what roles an individual can play depends on its properties. But talk of a state's playing a certain functional role strikes me as a confusing way of talking about the functional roles of the subject of the State. In the case of mental states, this confusion is abetted, it seems to me, by thinking of beliefs and desires as individuals somehow constituted in the brain. Perry Claims that it is simply commonsense to think of them this way (37). I disagree. But this is not the place to engage these issues.

4 I think it is implausible to suppose that any of these is identical with either of the others. Perry's having some property simply cannot be the same as his brain's having some property. I also think it is implausible to suppose that any of the properties involved in these states is identical with either in the other two. Perry himself has no neural properties, though his brain surely does.

5 But earlier, he wrote as follows:

6 I have corrected an amusing typographical error in this passage. In the original, epiphenomenal mental events are characterized as ‘nomological dangers.’

7 A similar proposal would be that while qualia do not logically supervene on causal or functional states they do so as a matter of contingent natural law. What I say in the body of the text applies to this proposal too.

8 One might think that such a position should not count as a version of physicalism. But, putting the point picturesquely, the position entalls that in creating the physical facts and establishing the laws of nature God had thereby created qualitative states. That sounds, to me, like a form of physicalism about qualia.

9 The idea that mental states have non-functional properties that supervene on functional states is discussed in Stalnaker, Robert ‘Comparing Qualia Across Persons,’ Philosophical Topics 26 (2000) 385–405CrossRefGoogle Scholar. Stalnaker's example is a desire's strength, which (in one sense, anyway) is a relational property, ordering the desire in relation to other desires. A desire's strength is not itself a functional property of the desire, even if the desire itself is a functional State. But he does not discuss what I will call a state's position within a System of states.

10 In chapter 4, Perry argues that the Zombie Argument, though advertised as an argument for dualism, is really an argument for epiphenomenalism. Perry argues persuasively that the possibility of a zombie world would show that qualia make no causal difference to the actual world. But, he notes, a dualist need not accept this epiphenomenalism and a physicalist need not deny it. But I am not sure how this is supposed to show that the Zombie Argument is really an argument for epiphenomenalism and not for dualism. For the issue is whether a physicalist could accept the possibility of a zombie world, and it seems clear that she could not. In fact, Perry seems to agree. What he says the physicalist can accept is the possibility of a world that lacks qualia and is physically just like the actual world but for those physical facts (whatever they are) that constitute the qualia. But this is not a zombie world, and is not the world Chalmers argues is possible. So I do not see how Perry's argument is supposed to succeed.

11 I might be misrepresenting Perry's position here. For, on his view, the content that Q is not P could be the subject matter content of S's belief, even though it is necessarily false. One might think this is enough to show that a world where Q is not P is conceivable. Perry does not clarify this point. If this is his view, then in response to the claim that zombies are conceivable he has to deny that anything conceivable is possible, and his aim in the book would then be to explain how one can be mistaken about what is possible and not, as I have represented it, to explain how one can be mistaken about what is conceivable. It is not clear to me from the text which of these aims is Perry's. But whatever his aim, his strategy is clear: the mistake is to be explained as deriving from confusing a contingency in one's means of representing the world for a contingency in the world itself.

12 Perry resists saying that the agent has such a belief, in part I think, because he believes that Claims about an agent's beliefs are Claims about ideas composed in her brain, and not just Claims about her dispositions: ‘When we ascribe a belief to a person about a certain individual and involving a certain property or relation, we suppose that the agent has a notion of that individual and an idea of that property or relation’ (134-5). It seems to me that this is building too much theoretical content into Claims about an agent's beliefs. One could, more cautiously, agree that such Claims are made true by facts about the ideas inside an agent's head while denying that what they claim is that such facts obtain. But I am doubtful about the truth of even this more cautious claim.

13 I am indebted to Andrew Hunter and to two anonymous reviewers for very helpful comments on an earlier draft of this paper. Part of section I was read at the 2002 Conference for the Scientific Study of Consciousness, in Barcelona, where I benefited from comments by Ned Block and Joe Lau.