Meditation VI: The Conceivability and Divisibility Arguments

The Argument Introduced

The Conceivability Argument occurs in Meditation VI. It is Descartes’ most celebrated argument. It was criticised in its day and has been ever since. The argument purports to establish that minds are non-physical substances and hence that a mind is not identical to any bit of the body, such as the brain. A person is a special unity of two substances: physical substance (the body) and mental substance (the mind). Only humans are such special unities. Animals have bodies but lack minds and angels have minds but lack bodies.

Here’s the passage:

First, I know that everything which I clearly and distinctly understand is capable of being created by God so as to correspond exactly with my understanding of it. Hence the fact that I can clearly and distinctly understand one thing apart from another is enough to make me certain that the two things are distinct, since they are capable of being separated, at least by God. The question of what kind of power is required to bring about such a separation does not affect the judgment that they are distinct. Thus, simply by knowing that I exist and seeing at the same time that absolutely nothing belongs to my nature or essence except that I am a thinking thing, I can infer correctly that my essence consists solely in the fact that I am a thinking thing. It is true that I may have (or, to anticipate, that I certainly have) a body that is very closely joined to me. But, nevertheless, on the one hand I have a clear and distinct idea of myself, in so far as I am simply a thinking, non-extended thing; and on the other hand I have a distinct idea of body, in so far as this is simply an extended, non-thinking thing. And accordingly, it is certain that I am really distinct from my body, and can exist without it.

The key lines are