 One important objection, advanced by (among others) Kripke (1972) and Chalmers (1996a), derives from Descartes's well-known argument in the Sixth Meditation (1641) that since he can clearly and distinctly conceive of himself existing apart from his body (and vice versa), and since the ability to clearly and distinctly conceive of things as existing apart guarantees that they are in fact distinct, he is in fact distinct from his body.