The Knowledge Argument Against Dualism

Paul Churchland argues that Frank Jackson's Knowledge Argument against physicalism is so strong that if it defeated physicalism it would, at the same time, defeat ‘substance dualism’. The purpose of this paper is to articulate this ‘parity of reasons’ objection. In the first part of the paper, I discuss Churchland's argument. I demonstrate that although his formulation of the objection is not wholly satisfactory, it may be revised so that the Knowledge Argument would defeat a certain form of dualism. In the second part, I apply the parity of reasons objection to David Chalmers' dualism. Chalmers rejects physicalism on the basis of the Knowledge Argument and introduces two possible forms of dualism. I show that of those two forms of dualism, Chalmers has to endorse the one that he does not prefer because the other is vulnerable to the parity of reasons objection.