ABSTRACT
The metaphysical nature of the mind is one of the main problems of philosophy. It took center stage in the early modern period when Descartes argued that the mind is something wholly nonphysical and nonmaterial. The identity theorist claims that all properties possessed by the mind are possessed by the brain and vice versa. There is a variant of the identity theory which claims not only that each mental property has a correlated neural property but that such pairs of correlated properties are really identical. To many philosophers, the prospect of property dualism is just as disconcerting as substance dualism. Philosophical behaviorism offers a theory of mental properties focusing on the meanings of the words by which such properties are expressed. Behaviourism promises a very thorough-going materialism that avoids both property dualism and substance dualism. Unlike behaviourism, functionalism acknowledges that mental states are "inner" states.
