That is not to say that I understand just how the first person and the third form two logically inseparable aspects of a single concept -- only that they do. This applies to all conscious mental states and events, and their properties. They are subjective, not in the sense that they are the subjects of a purely first-person vocabulary, but in the sense that they can be accurately described only by concepts in which nonobservational first-person and observational third-person attributions are logically inseparable. Such states are modifications of the point of view of an individual subject.
The problem, then, is how something that is an aspect or element of an individual's subjective point of view could also be a physiologically describable event in the brain -- the kind of thing which, considered under that description, involves no point of view and no distinctively immediate first-person attribution at all. I believe that as a matter of fact you can't have one without the other, and furthermore that the powerful intuition that it is conceivable that an intact and normally functioning physical human organism could be a completely unconscious zombie is an illusion -- due to the limitations of our understanding. Nevertheless those limitations are real. We do not at present possess the conceptual equipment to understand how subjective and physical features could both be essential aspects of a single entity or process.
Suppose, as seems likely, that I taste the smoke of my cigar when and only when my brain is in a certain physical state. What gets in the way of the thought that the experiential state of which I am introspectively aware is the physical state? The problem lies in the lack of any conceivable internal connection between a modification of my subjective point of view and a modification of the physico-chemical activity of my brain. The two may correspond extensionally as exactly as you like, but identity requires more than that. If they are the same state, it must be impossible for the one to exist without the other. And while we may have good empirical reasons to believe that that is true, the understanding of such an impossibility requires that the necessity of the connection between the two become intellectually transparent to us. In the case of conscious states and physiological states, it isn't just that we don't see such a necessary connection: it seems in advance that a necessary connection between two such different things is unimaginable. They seem logically unrelated.
It is very different from trying to imagine the possibility of a physico-chemical analysis of embryonic development, before one has the slightest inkling of what the analysis might be. In that case we can nevertheless understand the possibility in the abstract: there are no grounds for ruling it out a priori, since we know in general terms what it is to exhaustively analyze a largescale process into its microscopic or submicroscopic components. But that model will not help us with the mind and the brain. We are entitled to identify a familiar physical phenomenon like fire with a theoretically described process at the atomic level because the macroscopic properties of fire, including its causes and effects, can be derived from the microscopic account -- can be seen to be necessitated by it. The chemical analysis of fire and air reveals, for example, that it is a necessary truth that a fire confined to a small, airtight space will quickly go out. But we cannot see how a detailed account of what is going on in the brain could exhaustively explain the taste of a cigar -- not even if we could see how it explained all the physical effects of such an experience. So long as this explanatory gap remains, the identification of the states remains problematic.
This does seem to call for some revision in our way of conceiving of mind, or matter, or both. The difficulty is to do this without denying what is in front of your nose.
