Frank Jackson, “Epiphenomenal Qualia/What Mary Didn’t Know” and “Postscript on Qualia”

(1) Jackson (in “Epiphenomenal Qualia” and in “What Mary Didn’t Know”) and Chalmers (in “The Hard Problem of Consciousness” and “The Puzzle of Conscious Experience”) both argue against physicalism. (You may take the thesis Jackson calls “physicalism” to be the same as the one Chalmers calls “materialism.”) Jackson, in a subsequent article, “Postscript on Qualia,” now argues for physicalism essentially on the ground that we should not “have opinions that outrun what is required by the best theory of those opinions’ causal origins.” What do you think he means by this? If physicalism is true, where do you think the knowledge argument and the zombie argument go wrong? If physicalism is false, what do you think is the flaw in Jackson’s later argument for it? (Make sure to define clearly what you think Jackson and Chalmers mean by “physicalism,” i.e. materialism.)