Someone e-mailed me a pointer to these discussions. I'm in the middle of four weeks on the road at conferences, so just a quick comment. It seems to me that although you present your arguments as arguments against the thesis (Z) that zombies are logically possible, they're really arguments against the thesis (E) that consciousness plays no causal role. Of course thesis E, epiphenomenalism, is a much easier target. This would be a legitimate strategy if thesis Z entails thesis E, as you appear to assume, but this is incorrect. I endorse Z, but I don't endorse E: see my discussion in "Consciousness and its Place in Nature", especially the discussion of interactionism (type-D dualism) and Russellian monism (type-F monism). I think that the correct conclusion of zombie-style arguments is the disjunction of the type-D, type-E, and type-F views, and I certainly don't favor the type-E view (epiphenomenalism) over the others. Unlike you, I don't think there are any watertight arguments against it, but if you're right that there are, then that just means that the conclusion of the argument should be narrowed to the other two views. Of course there's a lot more to be said about these issues, and the project of finding good arguments against Z is a worthwhile one, but I think that such an argument requires more than you've given us here.