Online research in philosophy

According to many philosophers, there is an explanatory gap between physical truths and phenomenal truths. Someone could know all the physical truths about the world, and in particular, all the physical information about the brain and the neurophysiology of vision, and still not know what it is like to see red (Jackson 1982, 1986). According to a similar example, someone could know all the physical truths about bats and still not know what it is like to be a bat (Nagel 1974). We can conceive of an individual that is physically identical to me, molecule per molecule, but does not have any phenomenally conscious state whatsoever (Chalmers 1996). Some philosophers have argued that the explanatory gap shows that we cannot explain consciousness in physical terms (Levine 2001), or even that phenomenal consciousness is not physical and therefore physicalism is false (Chalmers 1996, 2002).

The thesis that there is a troublesome explanatory gap between the phenomenal aspects of experiences and the underlying physical and functional states is given a number of different interpretations. It is shown that, on each of these interpretations, the thesis is false. In supposing otherwise, philosophers have fallen prey to a cognitive illusion, induced largely by a failure to recognize the special character of phenomenal concepts.

Some people believe that there is an “explanatory gap” between the facts of physics and certain other facts about the world—for example, facts about consciousness. The gap is presented as a challenge to any thoroughgoing naturalism or physicalism. We believe that advocates of the explanatory gap have some reasonable expectations that cannot be merely dismissed. We also believe that naturalistic thinkers have the resources to close the explanatory gap, but that they have not adequately explained how and why these resources work. In this paper we isolate the legitimate explanatory demands in the gap reasoning, as it is defended by Chalmers and Jackson (2001). We then argue that these demands can be met. Our solution involves a novel proposal for understanding the relationship between theories, explanations, and scientific identities.

Some people believe that there is an “explanatory gap” between the facts of physics and certain other facts about the world—for example, facts about consciousness. The gap is presented as a challenge to any thoroughgoing naturalism or physicalism. We believe that advocates of the explanatory gap have some reasonable expectations that cannot be merely dismissed. We also believe that naturalistic thinkers have the resources to close the explanatory gap, but that they have not adequately explained how and why these resources work. In this paper we isolate the legitimate explanatory demands in the gap reasoning, as it is defended by Chalmers and Jackson (2001). We then argue that these demands can be met. Our solution involves a novel proposal for understanding the relationship between theories, explanations, and scientific identities.

The explanatory gap refers to the lack of concepts for understanding “how it is that . . . a state of consciousness comes about as a result of irritating nervous tissue.” By assuming that there are colours in the outside world, Block needlessly widens this gap and Lycan and Kitcher simply fail to see the gap. When such assumptions are abandoned, an unnecessary and incomprehensible constraint disappears. It then becomes clear that the brain can use its own neural language for representing aspects of the outside world. While this may not close the gap, it becomes clearer where we need new concepts.

I argue that the explanatory gap is generated by factors consistent with the view that qualia are physical properties. I begin by considering the most plausible current approach to this issue based on recent work by Valerie Hardcastle and Clyde Hardin. Although their account of the source of the explanatory gap and our potential to close it is attractive, I argue that it is too speculative and philosophically problematic. I then argue that the explanatory gap should not concern physicalists because it makes excessive demands on physical theory.

It is argued that the explanatory gap argument, according to which it is fundamentally impossible to explain qualitative mental states in a physicalist theory of mind, is unsound. The main argument in favour of the explanatory gap is presented, which argues that an identity statement of mind and brain has no explanatory force, in contrast to "normal" scientific identity statements. Then it is shown that "normal" scientific identity statements also do not conform to the demands set by the proponent of the explanatory gap. Rather than accept all such gaps, it is argued that we should deny the explanatory gap in a physicalist theory of mind.

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.

The claim that there is an explanatory gap between physical and phenomenal properties is perhaps the leading current challenge to materialist views about the mind. Tye tries to block this challenge, not by providing an explanation to bridge the gap but by denying that phenomenalphysical identities introduce an explanatory gap. Since an explanatory gap exists only if there is something unexplained that needs explaining, and something needs explaining only if it can be explained (whether or not it lies within the power of human-beings to explain it), there is no gap. (Tye ????, p. ???) Tyes strategy differs crucially from the claim that identities never stand in need of explanation because they constitute ultimate explanations; for he allows that identities such as water = H?O are explainable. Unlike WATER and H?O, which are descriptive concepts, phenomenal concepts are perspectival and hence irreducible to descriptive concepts, according to Tye. The fact that something picked out by a perspectival concept is identical to something picked out by a non-perspectival concept cannot be explained.1 So, he concludes, phenomenalphysical identities need not be explained.

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).