ABSTRACT
Contemporary philosophy of mind is marked by its acceptance of one major strand in Cartesian thinking and its rejection of another. The strand that has been accepted is the causalist one: our psychological states are causally related to our behaviour, and thus they make a difference to what happens in the world of objects. Descartes accepted this and also held, of course, that mental states were states of an immaterial substance. This generated a key problem for him, namely to accommodate the causal interaction between mental and physical states. This is the part of his position which contemporary theorists resolutely reject. For them the only kind of substance is material substance. They therefore have to confront the question, if we abandon dualism, what is a mental state? In some way mental states must be states of a material substance. Different stories of how this can be the case have dominated philosophy of mind for the last fifty years or so.
