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Mary Meets Molyneux: The Explanatory Gap and the Individuation of Phenomenal Concepts1 It is widely accepted that physicalism faces its most serious challenge when it comes to making room for the phenomenal character of psychological experience, its so-called what-it-is-like aspect. The challenge has surfaced repeatedly over the past two decades in a variety of forms.2 In a particularly striking one, Frank Jackson considers a situation in which Mary, a brilliant scientist who knows all the physical facts there are to know about psychological experience, has spent the whole of her life in a black and white room. He asks, What will happen when Mary is released from her black and white room or is given a colour television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information. (Jackson 1986: 130) 1 Versions of this paper were delivered to audiences at Rutgers University, Columbia University, and the Queen’s University Belfast. I am grateful to those audiences for comments. I am also indebted to Tim Bayne, John Heil, Bill Lycan, Graham Macdonald, Ruth Millikan, and Mark Sainsbury. 2 For those who think that the challenge cannot be met by physicalists, see Jackson 1982, 1986; Nagel 1974, 1986; Levine 1983, 1988, 2001; McGinn 1989; and Chalmers 1996. For those who think that it can, see Papineau 1994, Lycan 1996, Loar 1990, and Tye 1999, 2000, 2001. Despite their differences, particularly with respect to whether failure to meet the challenge shows that physicalism is false (cf. Jackson and Levine), all..

One of the main strategies against conceivability arguments is the so-called phenomenal concept strategy, which aims to explain the epistemic gap between physical and phenomenal truths in terms of the special features of phenomenal concepts. Daniel Stoljar has recently argued that the phenomenal concept strategy has failed to provide a successful explanation of this epistemic gap. In this paper my aim is to defend the phenomenal concept strategy from his criticisms. I argue that Stoljar has misrepresented the resources of the strategy, which can indeed accomplish the required explanatory task, once it is properly understood.

Chalmers (The Conscious Mind, Oxford Unversity Press, Oxford 1996) has argued for a form of property dualism on the basis of the concept of a zombie (which is physically identical to normals), and the concept of the inverted spectrum. He asserts that these concepts show that the facts about consciousness, such as experience or qualia, are really further facts about our world, over and above the physical facts. He claims that they are the hard part of the mind-body issue. He also claims that consciousness is a fundamental feature of the world like mass, charge, etc. He says that consciousness does not logically supervene on the physical and all current attempts to assert an identity between consciousness and the physical are just as non-reductive as his dualism. They are simply correlations and are part of the problem of the explanatory gap. In this paper, three examples of strong identities between a sensation or a quale and a physiological process are presented, which overcome these problems. They explain the identity in an a priori manner and they show that consciousness or sensations (Q) logically supervene on the physical (P), in that it is logically impossible to have P and not to have Q. In each case, the sensation was predicted and entailed by the physical. The inverted spectrum problem for consciousness is overcome and explained by a striking asymmetry in colour space. It is concluded that as some physical properties realize some sensations or qualia that human zombies are not metaphysically possible and the explanatory gap is bridged in these cases. Thus, the hard problem is overcome in these instances.

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. (Nagel, 1974, Levine, 1983) 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. (See Crick (1994).) Still, that identity itself calls out for explanation! Proponents of an explanatory gap disagree about whether the gap is permanent. Some (e.g. Nagel, 1974) 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. (McGinn, 1991) Still others say that the gap is a consequence of the fundamental nature of consciousness.

Assume that a quale as we experience it is a perspective on an underlying physical state, rather than the physical state as such – the reality as known as distinct from the reality as such. Assume, further, that this inner perspective is integral to, and materially co-extensive with, the physical state itself. Assume, finally, that the physical state in question is known as a brain state of a particular kind by an external observer of the brain in which it occurs. The result is a perspective in which a quale is entirely physical; a position that resolves several known difficulties for physicalism, including those associated with the explanatory gap, Jackson’s knowledge argument, and Chalmers’ hard problem of consciousness.

A number of philosophers think that, while we cannot explain how the mind is physical, we can know that it is physical, nonetheless. That is, they accept both the explanatory gap between the mental and the physical and ontological physicalism. I argue that this position is unstable. Among other things, I argue that once one accepts the explanatory gap, the main argument for ontological physicalism, the argument from causation, looses its force. For if one takes physical/nonphysical causation and ontological physicalism to be equally mysterious, as physicalists who accept the explanatory gap are inclined to do, there is little justification for accepting ontological physicalism rather than rejecting the causal closure of the physical.

According to the self-representational theory of consciousness – self- representationalism for short – a mental state is phenomenally conscious when, and only when, it represents itself in the right way. In this paper, I consider how self- representationalism might address the alleged explanatory gap between phenomenal consciousness and physical properties. I open with a presentation of self- representationalism and the case for it (§1). I then present what I take to be the most promising self-representational approach to the explanatory gap (§2). That approach is threatened, however, by an objection to self-representationalism, due to Levine, which I call the just more representation objection (§3). I close with a discussion of how the self-representationalist might approach the objection (§4).

A number of philosophers think that, while we cannot explain how the mind is physical, we can know that it is physical, nonetheless. That is, they accept both the explanatory gap between the mental and the physical and ontological physicalism. I argue that this position is unstable. Among other things, I argue that once one accepts the explanatory gap, the main argument for ontological physicalism, the argument from causation, looses its force. For if one takes physical/nonphysical causation and ontological physicalism to be equally mysterious, as physicalists who accept the explanatory gap are inclined to do, there is little justification for accepting ontological physicalism rather than rejecting the causal closure of the physical.

In this paper, we present an account of phenomenal consciousness. Phenomenal consciousness is experience, and the problem of phenomenal consciousness is to explain how physical processes?behavioral, neural, computational?can produce experience. Numerous thinkers have argued that phenomenal consciousness cannot be explained in functional, neural or information-processing terms (e.g. Block 1990, 1994; Chalmers 1996). Different arguments have been put forward. For example, it has been argued that two individuals could be exactly alike in functional/computational/behavioral measures, but differ in the character of their experience. Though such persons would behave in the same way, they would differ in how things felt to them (for example, red things might give rise to the experience in one that green things give rise to in the other). Similarly, it has been held that two individuals could be functionally/computationally/behaviorally alike although one of them, but not the other, is a mere zombie, that is, a robot-like creature who acts as if it has experience but is in fact phenomenally unconsciousness. For any being, it has been suggested, the question whether it has experience (is phenomenally conscious) cannot be answered by determining that it is an information-processor of this or that sort. The question is properly equivalent to the question whether there is anything it is like to be that individual (Nagel 1974). Attempts to explain consciousness in physical or information-processing terms sputter: we cannot get any explanatory purchase on experience when we try to explain it in terms of neural or computational processes. Once a particular process has been proposed as an explanation, we can then always reasonably wonder, it seems, what it is about that particular process that make it give rise to experience. Physical and computational mechanisms, it seems, require some further ingredient if they are to explain experience. This explanatory shortfall has aptly been referred to as "the explanatory gap" (Levine 1983)..

Confronted with the apparent explanatory gap between physical processes and consciousness, there are many possible reactions. Some deny that any explanatory gap exists at all. Some hold that there is an explanatory gap for now, but that it will eventually be closed. Some hold that the explanatory gap corresponds to an ontological gap in nature.