Substance Dualism

There are two important concepts deployed in this notion. One is that of substance, the other is the dualism of these substances. A substance is characterized by its properties, but, according to those who believe in substances, it is more than the collection of the properties it possesses, it is the thing which possesses them. So the mind is not just a collection of thoughts, but is that which thinks, an immaterial substance over and above its immaterial states. Properties are the properties ofobjects. If one is a property dualist, one may wonder what kinds of objects possess the irreducible or immaterial properties in which one believes. One can use a neutral expression and attribute them to persons, but, until one has an account of person, this is not explanatory. One might attribute them to human beings quaanimals, or to the brains of these animals. Then one will be holding that these immaterial properties are possessed by what is otherwise a purely material thing. But one may also think that not only mental states are immaterial, but that the subject that possesses them must also be immaterial. Then one will be a dualist about that to which mental states and properties belong as well about the properties themselves. Now one might try to think of these subjects as just bundles of the immaterial states. This is Hume’s view. But if one thinks that the owner of these states is something quite over and above the states themselves, and is immaterial, as they are, one will be a substance dualist.
Substance dualism is also often dubbed ‘Cartesian dualism’, but some substance dualists are keen to distinguish their theories from Descartes’s. E. J. Lowe, for example, is a substance dualist, in the following sense. He holds that a normal human being involves two substances, one a body and the other a person. The latter is not, however, a purely mental substance that can be defined in terms of thought or consciousness alone, as Descartes claimed. But persons and their bodies have different identity conditions and are both substances, so there are two substances essentially involved in a human being, hence this is a form of substances dualism. Lowe (2006)claims that his theory is close to P. F. Strawson’s (1959), whilst admitting that Strawson would not have called it substance dualism.