Okay, just for the moment, here are the links to Tim Dean's series of posts on Philip Kitcher's The Ethical Project: one; two; three; four; five.
I'll be back with a bit more to say about all this - though again, my own review of The Ethical Project is available online - so this post is a bit of a placeholder until I edit it.
Edit: I'm not actually going to add much to this post - rather, I'll add it to the growing list of things that I've promised to return to at some point. I do want to talk more about the functionalist account of morality, which I also subscribe to in a general way. I think that this view - which is represented in Mackie's Ethics: Inventing Right and Wrong, Kitcher's new book, Tim Dean's work, and many others - and has many predecessors going back at least as far as the Greek sophist Protagoras - is the way ahead. It involves examining how the phenomenon of morality (and with it specific moral norms) has contributed to social survival and social coordination. It tends to reveal that morality is not what it is commonly imagined to be, something objectively binding in the nature of things, but rather something that serves widely held desires (though it may sometimes misfire or even backfire).
There's much scope for researching this in more detail, trying to pin it down more precisely, and exploring its real-world implications. But whatever more I want to say about it can await another post, I think. Allow me, at this stage, just to commend the posts that I linked to. Some of the threads that resulted are also interesting. I noticed a familiar name or two.
I also think that the view has some problems that need to be examined carefully, such as a problem with the whole idea of "function" - that doesn't render it false, but it opens up areas where more work needs to be done.