From Towards a Science of Consciousness 3 CogNet Proceedings
It is natural to hope that an explanation of consciousness might be a physical explanation. Physical explanations have had extraordinary success elsewhere in science. In biology, chemistry, geology, physiology, and even in aspects of psychology, we have found that physical analyses can account for all sorts of phenomena in a reasonably complete and satisfying way. Given this track record, one might well expect that a physical explanation of consciousness is on its way. And indeed, investigation of the neurophysiological basis of consciousness has already yielded many insights into the phenomenon.
But some have argued that any purely physical explanation of consciousness will be incomplete. Neurophysiology will very likely yield a systematic correlation between states of the brain and states of consciousness, but will this correlation be a complete explanation? It has often been suggested that no physical account tells us why there should be states of subjective experienceæthe direct experience of colors, pains, emotions, and other phenomenological aspects of our mental lives. Given any physical account, one can ask why that process should yield consciousness; and many have suggested that a physical theory alone cannot answer this question.
One can argue, for example, that it is a least internally consistent to suppose that there could be a being physically identical to one of us, but who is not conscious at all. This is an odd possibility, and there is little reason to believe it corresponds to anything in the actual world, but it is arguably at least logically possible, in that the notion is not contradictory. If so, this suggests that physical theory is logically compatible with both the presence and the absence of consciousness. And this in turn suggests that no purely physical theory can explain why consciousness exists in the first place. Levine (1983) has put the point by saying that there is an explanatory gap between physical processes and conscious experience.
Theorists of consciousness are divided both on whether there is an explanatory gap, and on what follows. Some deny that there is any gap, or suggest that it has already been closed. It is probably fair to say that most think, however, that there is at least a prima facie explanatory gap. From here, some go on to argue that consciousness is not a wholly physical phenomenon. But others resist this conclusion.
The four contributors to this section all accept that there is at least a prima facie explanatory gap, but they differ in where they go from there. In different ways, each of them is looking for a way to accommodate consciousness within a physical view of the world, while still taking the first-person phenomena as real. This leads down interesting pathways.
Joseph Levine, who introduced the term explanatory gap, thinks that the gap may be uncloseable, but that consciousness may be physical all the same. That is, there is an epistemological gap, but no ontological gap. In this chapter, he analyzes the roots of the gap. In particular, he investigates how it can be that given that water and consciousness are both physical processes, one can be explainable while the other is not.
Robert Van Gulick holds that there is a prima facie explanatory gap, but that it may eventually be closed. To close the explanatory gap, we need to revise our concepts, in a way that we cannot yet anticipate. With such a revision, it may no longer seem internally consistent to suppose that any physical process could take place without consciousness. He uses this idea to address some arguments by Chalmers (1996) for the conclusion that consciousness is nonphysical.
Galen Strawson, whose 1994 book discusses the problems of experience in depth, holds that experiential phenomena are physical. But this does not mean we need to deflate experience to something less than it is; rather, we have to expand our concept of the physical. He argues that there is more to the physical world than physical theory specifies. Once we understand the physical as it is in itself, rather than as described by physical theory, we will see that it has room for experience in its underlying intrinsic nature. He calls the resulting position "realistic monism."
Gregg Rosenberg pursues a related idea, arguing that we have to "re-enchant" our conception of the physical world for reasons that are independent of consciousness, and that once we do so, we will see how consciousness can fit in. By making an analogy with ConwayÕs game of "Life," he argues that our theory of the physical world is incomplete: it specifies abstract patterns and bare differences, but no underlying nature. He argues that causation has two aspects: an external aspect characterized by physical theory, and an internal aspect about which physical theory is silent. He argues that consciousness may be tied to the internal aspect of physical causation, giving it a deep and fundamental place in the natural order.
Many more chapters on these issues can be found in Block, Flanagan, and Guzeldere (1997) and Shear (1997).
Block, N., O. Flanagan, and G. Guzeldere. (Eds.) 1997. The Nature of Consciousness: Philosophical Debates. MIT Press.
Chalmers, D. J. 1996. The Conscious Mind: In Search of a Fundamental Theory. Oxford University Press.
Levine, J. 1983. Materialism and qualia: The explanatory gap. in Pacific Philosophical Quarterly 64:354Ð61.
Shear, J. (Ed.) 1997. Explaining Consciousness: The Hard Problem. MIT Press.
Strawson, G. 1994. Mental Reality. MIT Press.