Divisibility Argument

DIVISIBILITY ARGUMENT

This paper will discuss the dualism's Divisibility Argument. This argument relies on Leibniz's Law and uses a different property to prove the distinctness of brain states of mental states. Mary, who is a materialist, presents several objections to that argument. Her main objection corresponds to the first/third-person approach. She believes that Dave presents that argument only from the first-person approach, which is introspection, and totally disregards the third-person approach, which is observation of another mind. Mary's objections will follow by the Dave's response on them from the dualist's point of view.

The purpose of the Divisibility Argument is to prove that mental states are different from the brain states. My body, which includes my brain, is divisible. However, I cannot conceive of my mind as divisible. Therefore, my mind is distinct from any part of my body.

Descartes was the first who established the Divisibility Argument. He held that the two components which constitute man had an independent origin and are of a fundamentally different nature. The body is divisible, since it can be separated for example, my leg or my hand can be cut off; my brain can be cut on half. However, the idea of the divisible mind is inconceivable.

This argument relies on the Leibniz's Law. It is a principle about identity, which says, "if an object or event X is identical with an object or event Y, then X and Y have all of the same properties." So if X and Y have any different properties, then X can not be identical with Y. Divisibility Argument uses a different property to prove the distinctness of brain states and mental states: the property of being indivisible. In this case, the mind has a property and brain lacks it. The body can be divided, however, it cannot be done with the mind.

Mary has several objections to this argument. First, she believes that the mind is an entity, which is composed of several mental states: thoughts, beliefs, memories, desires, etc. Mary strongly disagrees with Descartes' claim that the mind employs itself in its different properties: willing, desiring, understanding, and so on. Secondly, she clarifies the meaning of the word "conceive" in the Dave's argument. The term "conceive" might mean either "imagine" or "understand." Imagining literally involves "forming an image of" or "picturing" in one's mind, whereas understanding is more "conceptual" and does not require the ability to picture something. In case, Dave interprets the word "conceive" as "imagine" in the second premise of the argument, this premise becomes untrue. The fact that he cannot imagine something to be the case does not make it true in everyone's case. Different minds can imagine different things. However, if Dave implies "understand" as a meaning of "conceive" the second premise still remains doubtful. The fact that Dave cannot understand