Joseph Levine (born January 17, 1952) is an American philosopher at the University of Massachusetts Amherst who received his PhD from Harvard University in 1981. He works on philosophy of mind and is best known for formulating the explanatory gap argument against a materialist explanation for consciousness. This has been cited as a precursor to David Chalmers's formulation of the hard problem of consciousness and as one of the main objections materialist theories in philosophy of mind must address. The idea of the explanatory gap is that an unbridgeable gap exists when trying to comprehend consciousness from the perspective of natural science, as a scientific explanation of mental states would require a reduction from a physical process to phenomenal experience. The property of mental stat