McGinn on the Mind- Body Problem

Colin McGinn ('Can we Solve the Mind-Body Problem?', Mind i969, p. 349) argues as follows. The determination of states of consciousness by the brain seems to us mysterious and unintelligible. But since it happens, it must have an explanation. The explanation must involve some property P of the brain, whereby brain-states produce states of consciousness. P is unknown to us, and must always remain unknown, because sensation, which is our only source of information about material objects, reveals to us only their spatial properties, and P is not such a property. Therefore we can never understand how the brain produces consciousness, and the relation between them must remain mysterious. Our bafflement arises from the complete diversity of the two entities to be causally related, as far as we can understand them. The brain is described by modern physicists purely in spatial terms motions, tendencies to move, and the capacity to make other things move; and this kind of description is completely inapplicable to consciousness. As McGinn says (p. 357) "Consciousness does not seem made up out of smaller spatial processes'. So consciousness cannot be fitted into the structure of the world as described by physics. I agree that this description cannot be complete, though it does seem to be sufficient for the purpose of causally accounting for what happens in the material world, including (there is reason to believe) human nervous systems. Nothing can be completely described by its spatial properties only; what moves must be something of some sort. I agree also that we have no means of access to any other properties of matter, not because spatial properties are the only ones presented to us in sensation, but because we have no good reason for attributing the others to material things. It is therefore plausible to argue that the mysteriousness of brain-mind causation is due to our ignorance of the nature of material objects in general and brains in particular, and that if only we could know the other properties the bafflement would disappear. But if the basic problem is the discrepancy between the properties of the brain and those of consciousness, I am not convinced that McGinn's property P could solve it. If variations in P can occur independently of the spatial properties of the brain, it cannot play its intended part as a mediator between brain and consciousness in a theory accounting for the physical determination of conscious states. If, on the other hand, its variations are wholly determined by these spatial properties, shall we not have the same sort of misfit between cause and effect which disturbed us in the causal relation between brain and consciousness? If we cannot make sense of a causal relation between heterogeneous entities, then to allay our disquiet P has to be sufficiently homogeneous with the physical to be a plausible effect of physical causes, and sufficiently homogeneous with consciousness to be a plausible cause of conscious effects. I doubt whether these requirements could both be met.