The ‘real’ issue concerns the status of qualia, that is, the subjective sensory states into which we are thrown when looking at a yellow leaf, hearing a musical chord, sniffing a camembert, or running our fingers over a piece of sandpaper. Is it possible to provide a satisfactory account of such states using only the resources of a materialist functionalism? Or is it the case -- as it has seemed to many, and as it seems to David Chalmers -- that (...) once we have said all there is to say about the physical basis of, and the functional role of, such states, there remains an uneliminable residue: the brute qualitative matter of ‘what it is like’ to sniff the camembert? Since it is extraordinarily hard to tackle this question head-on, we seek the leverage afforded by the notion of the philosopher's zombie, the point being that if we have a coherent intuition to the effect that there is indeed such a residue, then we ought to be able to conceive of the zombie. Just subtract the residue while leaving all the physical/functional stuff in place. Conversely, if it transpires that the notion of the philosopher's zombie breaks down under stress, this would seem to indicate that the intuition of the ineliminable residue is itself problematic. The ‘remedy’ for a belief in zombies is the sort of Dennettian exercise in imagination proposed in this paper. One must be forced to recognize the huge gulf between the simple informational economies of the thermostat, and even the PC, and the amazingly subtle and layered informational economy of a normal human being. Taking the PC, or the severely degraded registrations of actual blindsight victims, as the model, one may fool oneself into thinking one has imagined something when one has not really confronted its detailed implications. This piece will have accomplished its aim if it encourages a few readers to take the latter possibility more seriously than hitherto. (shrink)

This much-anticipated book is a detailed elaboration and defense of Levine’s influential claim that there is an “explanatory gap” between the mental and the physical.

Let psychologism be the doctrine that whether behavior is intelligent behavior depends on the character of the internal information processing that produces it. More specifically, I mean psychologism to involve the doctrine that two systems could have actual and potential behavior _typical_ of familiar intelligent beings, that the two systems could be exactly alike in their actual and potential behavior, and in their behavioral dispositions and capacities and counterfactual behavioral properties (i.e., what behaviors, behavioral dispositions, and behavioral capacities they would (...) have exhibited had their stimuli differed)--the two systems could be alike in all these ways, yet there could be a difference in the information processing that mediates their stimuli and responses that determines that one is not at all intelligent while the other is fully intelligent. (shrink)

What is Functionalism? Functionalism is one of the major proposals that have been offered as solutions to the mind/body problem. Solutions to the mind/body problem usually try to answer questions such as: What is the ultimate nature of the mental? At the most general level, what makes a mental state mental? Or more specifically, What do thoughts have in common in virtue of which they are thoughts? That is, what makes a thought a thought? What makes a pain a pain? (...) Cartesian Dualism said the ultimate nature of the mental was to be found in a special mental substance. Behaviorism identified mental states with behavioral dispositions; physicalism in its most influential version identifies mental states with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to sensory inputs and behavioral outputs. Functionalism is one of the major theoretical developments of Twentieth Century analytic philosophy, and provides the conceptual underpinnings of much work in cognitive science. (shrink)

Experiences and beliefs are different sorts of mental states, and are often taken to belong to very different domains. Experiences are paradigmatically phenomenal, characterized by what it is like to have them. Beliefs are paradigmatically intentional, characterized by their propositional content. But there are a number of crucial points where these domains intersect. One central locus of intersection arises from the existence of phenomenal beliefs: beliefs that are about experiences.

Materialism in the philosophy of mind is the thesis that the ultimate nature of the mind is physical; there is no sharp discontinuity in nature between the mental and the non-mental. Anti-materialists asser t that, on the contrary, mental phenomena are different in kind from physical phenomena. Among the weapons in the arsenal of anti-materialists, one of the most potent has been the conceivability argument. When I conceive of the mental, it seems utterly unlike the physical. Anti-materialists insist that from (...) this intuitive difference we can infer a genuine meta-physical difference. Materialists retor t that the nature of reality, including the ultimate natures of its constituents, is a matter for discovery; an objective fact that cannot be discerned a priori. In this paper I under take to provide an explicit analysis of the dialectic that surrounds the conceivability argument. My principal conclusion is that the materialist is right in resisting the reasoning that star ts from considerations of what is conceivable and ends with genuine metaphysical conclusions. However my approach is much more sympathetic to the anti-materialist position than is the standard materialist line, and I will provide a limited defense of some crucial aspects of the anti-materialist position. Materialism will emerge from this fight intact, but shaken. (shrink)

There is a long tradition in philosophy of using a priori methods to draw conclusions about what is possible and what is necessary, and often in turn to draw conclusions about matters of substantive metaphysics. Arguments like this typically have three steps: first an epistemic claim , from there to a modal claim , and from there to a metaphysical claim.

This appeared in Philosophy and Phenomenological Research 59:473-93, as a response to four papers in a symposium on my book The Conscious Mind . Most of it should be comprehensible without having read the papers in question. This paper is for an audience of philosophers and so is relatively technical. It will probably also help to have read some of the book. The papers I’m responding to are: Chris Hill & Brian McLaughlin, There are fewer things in reality than are (...) dreamt of in Chalmers’ philosophy Brian Loar, David Chalmers’ The Conscious Mind Sydney Shoemaker, On David Chalmers’ The Conscious Mind Stephen Yablo, Concepts and consciousness Contents. (shrink)

This paper was chosen by The Philosopher’s Annual as one of the ten best articles appearing in print in 2000. Reprinted in Volume XXIII of The Philosopher’s Annual. In his very influential book David Chalmers argues that if physicalism is true then every positive truth is a priori entailed by the full physical description – this is called “the a priori entailment thesis – but ascriptions of phenomenal consciousness are not so entailed and he concludes that Physicalism is false. As (...) he puts it, “zombies” are metaphysically possible. I attempt to show that this argument is refuted by considering an analogous argument in the mouth of a zombie. The conclusion of this argument is false so one of the premises is false. I argue at length that this shows that the original conceivability argument also has a false premise and so is invalid. (shrink)

The explanatory gap . Consciousness is a mystery. No one has ever given an account, even a highly speculative, hypothetical, and incomplete account of how a physical thing could have phenomenal states. Suppose that consciousness is identical to a property of the brain, say activity in the pyramidal cells of layer 5 of the cortex involving reverberatory circuits from cortical layer 6 to the thalamus and back to layers 4 and 6,as Crick and Koch have suggested for visual consciousness. .) (...) Still, that identity itself calls out for explanation! Proponents of an explanatory gap disagree about whether the gap is permanent. Some say that we are like the scientifically naive person who is told that matter = energy, but does not have the concepts required to make sense of the idea. If we can acquire these concepts, the gap is closable. Others say the gap is uncloseable because of our cognitive limitations. Still others say that the gap is a consequence of the fundamental nature of consciousness. (shrink)

This paper engages with two compelling challenges to physicalism, each designed to show that the nature of experience is elusive from the standpoint of physical science. It is argued that the physicalist is ultimately well placed to meet both challenges.

What is Functionalism? Functionalism is one of the major proposals that have been offered as solutions to the mind/body problem. Solutions to the mind/body problem usually try to answer questions such as: What is the ultimate nature of the mental? At the most general level, what makes a mental state mental? Or more specifically, What do thoughts have in common in virtue of which they are thoughts? That is, what makes a thought a thought? What makes a pain a pain? (...) Cartesian Dualism said the ultimate nature of the mental was to be found in a special mental substance. Behaviorism identified mental states with behavioral dispositions; physicalism in its most influential version identifies mental states with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to sensory inputs and behavioral outputs. Functionalism is one of the major theoretical developments of Twentieth Century analytic philosophy, and provides the conceptual underpinnings of much work in cognitive science. (shrink)

In Section 5 of his interesting article, Goldman suggests that the consideration of imaginary cases can be valuable in the analysis of our psychological concepts. In particular, he argues that we can imagine a system that is isomorphic to us under any functional description, but which lacks qualitative mental states, such as pains and color sensations. Whether or not such a being is empirically possible, it certainly seems to be logically possible, or conceptually coherent. Goldman argues from this possibility to (...) the conclusion that our concepts of qualitative mental states cannot be analyzed entirely in functional terms. (shrink)

Philosophical zombies are exactly as physicalists suppose we are, right down to the tiniest details, but they have no conscious experiences. Are such things even logically possible? My aim is to contribute to showing not only that the answer is 'No', but why. My strategy has two prongs: a fairly brisk argument which demolishes the zombie idea; followed by an attempt to throw light on how something can qualify as a conscious perceiver. The argument to show that zombies are impossible (...) exploits the point that in order to be able to detect our own 'qualia' we should have to be somehow sensitive to them; which the zombie idea rules out. The attempt to make clear why my zombie twin must be conscious exploits the idea that we have a reasonably clear grasp of a 'Basic Package' of psychological concepts. (shrink)

Todd Moody’s Zombie Earth thought experiment is an attempt to show that ‘conscious inessentialism’ is false or in need of qualification. We defend conscious inessentialism against his criticisms, and argue that zombie thought experiments highlight the need to explain why consciousness evolved and what function(s) it serves. This is the hardest problem in consciousness studies.

One does not have to agree with the main conclusions of David Chalmers’s book in order to find it stimulating, instructive, and frequently brilliant. If Chalmers’s arguments succeed, his achievement will of course be enormous; he will have overthrown the materialist orthodoxy that has reigned in philosophy of mind and cognitive science for the last half century. If, as I think, they fail, his achievement is nevertheless considerable. For his arguments draw on, and give forceful and eloquent expression to, widely (...) held intuitions; seeing how they go astray, if they do, cannot help but deepen our understanding of the issues he is addressing. (shrink)

This paper examines the disagreement between those who think zombies are possible and those who think they are not. It aims to shed light on general questions about the nature of modal claims, and about the relation between metaphysical, semantic, and empirical questions. The views of three functional philosophers who provide unequivocal answers to the question “Are zombies possible?” are described.

I argue that zombies are inconceivable. More precisely, I argue that the conceivability-intuition that is used to demonstrate their possibility has been misconstrued. Thought experiments alleged to feature zombies founder on the fact that, on the one hand, they _must_ involve first-person imagining, and yet, on the other hand, _cannot_. Philosophers who take themselves to have imagined zombies have unwittingly conflated imagining a creature who lacks consciousness with imagining a creature without also imagining the consciousness it may or may not (...) possess. (shrink)

The problem of `conscious inessentialism' is examined in the literature, and an argument is presented that the presence of consciousness is indeed marked by a behavioural difference, but that this should be looked for at the cultural level of speech communities.

In this article I reply to the challenge set forth by Dennett in his critique of Flanagan and Polger (1995). Through careful textual analysis, I show that Dennett is presenting us with a dilemma and that this dilemma is the keystone of Dennett’s argument in his Consciousness Explained. I argue that one horn of the dilemma does not have the consequence that Dennett claims; Specifically, I argue that theories that allow for the possibility of non-conscious functional duplicates of conscious beings (...) (so called zombies) do not thereby entail epiphenomenalism about consciousness. I demonstrate how Dennett’s argument falls prey to a common mistake in reasoning about the functions of things, and recommend a correction. (shrink)

Chalmers' anti-materialist arguments are an interesting twist on a well-known argument form, and his naturalistic dualism is exciting to contemplate. Nevertheless, we think we can save materialism from the Chalmerian attack. This is what we do in the present paper.

In The Conscious Mind, D. Chalmers appeals to his semantic framework in order to show that conceivability, as employed in his "zombie" argument for dualism , is sufficient for genuine possibility. I criticize this attempt.

John Perry's book Knowledge, Possibility, and Consciousness is a lucid and engaging defense of a physicalist view of consciousness against various anti-physicalist arguments. In what follows, I will address Perry's responses to the three main anti-physicalist arguments he discusses: the zombie argument , the knowledge argument , and the modal argument.

Philosophical zombies are exactly as physicalists suppose we are, right down to the tiniest details, but they have no conscious experiences. Are such things even logically possible? My aim is to contribute to showing not only that the answer is 'No', but why. My strategy has two prongs: a fairly brisk argument which demolishes the zombie idea; followed by an attempt to throw light on how something can qualify as a conscious perceiver. The argument to show that zombies are impossible (...) exploits the point that in order to be able to detect our own 'qualia' we should have to be somehow sensitive to them; which the zombie idea rules out. The attempt to make clear why my zombie twin must be conscious exploits the idea that we have a reasonably clear grasp of a 'Basic Package' of psychological concepts. (shrink)

Moody's thought-experiment invoking zombies to demonstrate the uniqueness of consciousness is commended. His conclusions accord well with previous ones arrived at by Penrose, Chalmers and myself. All these works lead to a disturbing conclusion: onsciousness, as something distinct from the brain processes, interferes with physical reality. Ergo, it is no longer possible to adhere to any of the modern theories of mind that preserve the completeness of physics. This conclusion is, in principle, testable.

In Knowledge, Possibility and Consciousness I argue that the Zombie Argument, the Knowledge Argument, and the Modal Argument do not provide people with broadly common-sensical views about consciousness and the mental, and an inclination towards physicalism, any reasons not to be physicalists. That is, they do not support the doctrine of neo-dualism, advocated by Chalmers, Jackson, and others: although the mind may be the brain, qualia, the what-its-like properties of experiences that makes them experiences, are not physical properties.