Rene Descartes' Argument from Divisibility is the argument in which he claims that the mind and the body are two completely different things and thus cannot be identical. His argument is that the body is divisible because it can be physically altered like being cut in half. His belief is that the mind is indivisible because it is not a physical thing. Descartes believed that if two things do not have identical properties then they couldn't be the same. What Descartes was suggesting was that human beings' bodies are separate from their thoughts and that when the body dies the mind still lives, which had undertones of suggesting that there is an afterlife. Descartes called his concept Dualism.
The premise that the body is divisible is true because the body is a physical thing. The body has weight, mass, and interacting parts just like a machine such as a watch or an automobile. The premise that the mind is indivisible is not true because it is an assumption that the mind and body are two different things. "It is common knowledge that the brain is the central point of the body where all functions is controlled, mainly being sense perception and thought." (Lawhead, pg 283). The brain is as much a piece of physical matter the same way a rock is. Although much more complex than a rock, a brain and a rock have similar properties because they can be affected by the physical world and are bound by the laws of physics. All thoughts and functions come from the mind, in the sense that the word mind means our consciousness or being. It can be easy to assume that the mind and body are two separate things.
Mind and body are one in the same because if the mind were not affected by the physical world, then it would not have to follow the rules of the physical world. If the mind were truly a separate thing from the body, in theory people should be able to have outer body experiences as they please.