I evaluate and defend David Chalmers two-dimensional argument against materialism in light of criticisms. I motivate Chalmers argument by showing how the traditional anti-materialist arguments of Ren Descartes, Saul Kripke, and Frank Jackson have serious conceivability problems. Specifically, they take certain statements to be conceivable, which might not really be conceivable; and they take conceivability as a reliable guide to possibility, despite the lesson of Kripkean a posteriori necessities that conceivability is not a perfectly reliable guide to possibility. Subsequently, I explicate Chalmers argument and evaluate it in light of criticisms. I argue that there is a way of running Chalmers argument that stands up well against the criticisms, and I conclude by summing up the most important ways in which my discussion advances the literature.