Supervenience is a central notion in analytic philosophy. It is in the philosophy of mind that we find the term’s most frequent contemporary occurrence. It has traditionally been used to describe relationships between sets of properties in a manner which does not imply a strong reductive relationship. Supervenience is seen as the last hope for a nonreductive physicalism, which does not reduce the mental to the physical, the psychological to the neurophysiological. It is hard to see how the mind, if causally determined by the subvenient brain, is not therefore reducible to it.