Snarky, but pertinent.

This re-posting was prompted by a Sean Carroll article, that argued along similar lines...epiphenomenalism (one of a number of possible alternatives to physicalism) is incredible, therefore no zombies.

There are a number of problems with this kind of thinking.

One is that there may be better dualisms than epiphenomenalism.

Another is that criticising epi. doesn't show that there is a workable physical explanation of consciousness. There is no see-saw (titter-totter) effect whereby the wrongness of one theory implies the correctness of another. For one thing,there are more than two theories (see above). For another, an explanation has to explain...there are positive, absolute standards for explanation..you cannot say some Y is an an explanation, that it actually explains, just because some X is wrong, and Y is different to X. (The idea that physicalism is correct as an incomprehensible brute fact is known as the "new mysterianism" and probably isn't what reductionists physicalists and rationalists are aiming at).

Carroll and others have put forward a philosophical version of a physical account of consciousness, one stating in general terms that consciousness is a high-level, emergent outcome, of fine-grained neurological activity. The zombie argument (Mary's room, etc) are intended as handwaving philosophical arguments against that sort of argument. If the physicalist side had a scientific version of a physical account of consciousness, there would be no point in arguing against them philosophically, any more than there is a point in arguing philosophically against gravity. Scientific, as opposed to philosophical, theories are detailed and predictive, which allows them to be disproven or confirmed and not merely argued for or against.

And, given that there is no detailed, predictive explanation of consciousness, zombies are still imaginable, in a sense. If someone claims they can imagine (in the sense of picturing) a hovering rock, you can show that it is not possible by writing down some high school physics. Zombies are imaginable in a stronger sense: not only can they be pictuured, but the picture cannot be refuted.