"Dear Dan - the shade of pink is real. In denying its existence, you are getting things backwards. The important methodological maxim to remember is that appearances are real. This does not mean that every time there is an appearance of an apple, there is an apple. It just means that every time there is an appearance of an apple, there is an appearance of an apple. It also does not mean that every time someone thinks there is an appearance of an apple, there is one. People can be mistaken in their auto-phenomenology - but not as mistaken as you would have us believe."

Husserl, who was only concerned with getting phenomenology right and not with any underlying ontology, had a "principle of principles" which expresses the first half of what I mean by "appearances are real":

everything originarily offered to us in "intuition" is to be accepted simply as what it is presented as being, but also only within the limits in which it is presented there.

In Husserl, every mode of awareness is a form of intuition, including sense perception. He's saying that every appearance has an element of certainty, but only an element.

Appealing to Husserl may be overkill, but the point is, there is a limit to the degree one can plausibly deny appearance. Denying the existence of color in the way Dennett appears to be doing is like saying that 0 = 1 or that nothing exists - it's only worth doing as an exercise in cognitive extremism; try believing something impossible and see what happens.

However, people do end up believing weird things out of apparent philosophical necessity. I think this is what is going on with Dennett; he does understand that there is nothing like that shade of pink in standard physical ontology, so rather than engage in a spurious identification of pinkness with some neural property, he just says there is no pink. It's just a word. It's there to denote a bundle of cognitive and behavioral dispositions. But there is no pink as such, outside or inside the head.

He's willing to take this drastic step because the truth of physics seems so nailed down, so indisputable. However, there is a sense in which we do not know what physics is about. It's a black-box causal structure, whose inputs and outputs show up in our experience looking a certain way (looking like objects distributed in space). But that doesn't tell us how they are in themselves.

If you take the Husserlian principle ontologically - conscious experience is offering us a glimpse of the genuine nature of one small sliver of reality, namely, what happens in consciousness - and combine it with a general commitment to the causal structure of physics, you get what I'm now calling Reverse Monism. Reverse, because it's the reverse of the usual reductionism. The usual reductionism says this appearance, this part of consciousness, is actually atoms in space doing something. Reverse monism says instead: this appearance must be what some part of physics (some part of the physical brain) actually is.

If the usual reductionistic accounts of conscious experience were plausible as identities, reverse monism wouldn't introduce anything new; it would just be looking at the same identity from the other end of the equation. However, the only thing these alleged identities have going for them, generally, is a common causal role. The thing which is supposed to be the neural correlate of blueness is in the right position to be caused by blue light and to get a person talking about blueness. But the thing in itself (e.g. cortical neurons firing) is nothing like blueness as such.

Now as it happens, all these theories about the neural correlates of consciousness (such as Drescher's gensyms) are speculative in the extreme. We're not talking about anything as well-founded as the Krebs cycle or the inverse square law; these are speculations about how the truth might be. So we are not under any obligation to consider the mismatch between subjective ontology and neural ontology which occurs in these theories as itself an established fact, that we just have to learn to live with. We are free to look for other theories in which an ontologically plausible identity, and not just a causally adequate identity, is posited. That's what I'm on about.