“The dualist view of persons . . . is a form of substance dualism. . . . Substance dualism is the thesis that there are substances of two fundamentally distinct kinds in this world, namely, minds and bodies - or mental stuff and material stuff - and that a person is a composite entity consisting of a mind and a body, each of which is an entity in its own right. . . . a substance is thought to be something that has the capacity for independent existence. Descartes himself wrote, ‘The notion of a substance is just this - that it can exist by itself, that is without the aid of any other substance.’ . . . This means that if my mind is a substance, it can exist without any body existing, or any other mind existing.”