The most central metaphysical question about phenomenal consciousness is that of what constitutes phenomenal consciousness, whereas the most central epistemic question about consciousness is that of whether science can eventually provide an explanation of phenomenal consciousness. Many philosophers have argued that science doesn't have the means to answer the question of what consciousness is (the explanatory gap) but that consciousness nonetheless is fully determined by the physical facts underlying it (no metaphysical gap). Others have argued that the explanatory gap in the sciences entails a metaphysical gap. The explanatory gap exists, they say, because there are two fundamental properties in the world that do not reduce to one ano...