Derek,

You've said it's "not just neurons" and, more generally, you've expressed a strong skepticism towards the idea that we could ever scientifically grasp consciousness.  But such statements do not seem to combine well with your insistence that, before we make any philosophical judgments about consciousness, we must first try to figure out what it is.  You are making strong judgments about what consciousness is not, and also about probable limitations on our ability to learn about consciousness--all the while criticizing anybody who presumes to know enough about consciousness to make any judgments at all about it.  Am I wrong in noticing an inconsistency here?

You say, "I thought 'ordinary language' philosophy had gone out of fashion?" 

I don't know.  In any case, I was not advocating "ordinary language" philosophy, exactly.  But I wouldn't disparage it, either.  Philosophy involves ordinary languages, specialized languages, and varieties of formal logic.  I wouldn't exclude any of these from our collective toolbox.

My point was rather that the notion of consciousness (and related notions, such as intentionality, feelings, and experience) has its roots in ordinary language, and it is because of these roots that we are able to talk about notions like "the problem of consciousness" or "the mind/body problem."  The philosophical issues here come out of ordinary language, and they can only be resolved by making sense of our ordinary language.  This, I believe, can only be achieved by understanding the behavior which motivates that language.  However, this does not mean that our analysis must be limited to ordinary language.

I think you misunderstood the example of sleep-wakefulness cycles here.  The point was not that, by understanding the neurological aspects of sleep-wakefulness cycles, scientists have discovered something like the "true nature" of consciousness.  Rather, they have made some progress towards understanding the behavior which motivates our talk of consciousness.    Part of what it means to be conscious is to be awake, alert and active in the world.  By beginning to understand the neurological aspects of how wakefulness is regulated, we have come a step towards understanding the neurological functionality of consciousness.  This is not a step towards telling us "what consciousness is," but rather progress towards understanding how consciousness happens.

You ask, "Why so? If consciousness is not scientifically explicable, (which it may well not be) why should it be the exclusive preserve of science?"

The issue here relates to how we frame the problem.  You can define some aspect of human behavior out of observable existence (and so frame the problem in question-begging terms which defy objective analysis).  That would define it out of scientific discoverability; but what avenues of inquiry would it leave open?

It is possible that there are limitations on what science can do in the study of consciousness--it may be that human behavior is too complex for any feasible science to penetrate completely.  But that is not something we should assume.  So what basis is there for excluding some aspects of human behavior from scientific scrutiny?

I think the burden is on those who criticize science to give a reason why science has some limitations here.  The reason why I don't think this can be done is because such a reason would have to be analyzable objectively, and without appeal to absolutely subjective knowledge.