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.' (Law head, 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.
It cannot be done because the mind is confined to the body and therefore is part of the body. Outer body experiences people have claimed to have are nothing but dreams. When a person suffers trauma and claims to have had an outer body experience what they describe as experiencing is the same description of a dream. Everyone who truly dies never come back.
Dead men tell no tales. The mind is a part of the body just like the heart but more dynamic and complex in its nature and functioning. People who disagree and say that the Argument from Divisibility is a valid argument would say that the mind and body are two different things because the body is divisible and the mind is not. They would argue, as Descartes did, that if a person's body was altered in some way like having all of their limbs removed, then the person's body would be different, but their mind would remain unchanged. Another argument that could be made would be that our minds and our bodies are different because our bodies have no free will.
An example an opponent might give is a person driving a car. Their legs and feet control the acceleration while their arms and hands control the steering and shifting. Their eyes look forward at the road and even their ears listen for possible signs of danger such as a siren or a horn. All these functions an opponent might say could not happen without the free will of the mind telling the body what to do. A person not paying attention such as an inattentive driver could be argued as a separation of the mind and body, but the mind is just a functioning part of the body. It is possible for a person's heart, kidney, or other organ not to function properly.
When a person's organs are not working to full capacity it is the same as the mind not working to full capacity, thus, making the driver inattentive. The last argument an opponent might give is that science tells us about the things in our physical universe. Although science has not got to the point to where we know everything about our physical world, if it ever did get to that point, it still could not prove that the mind and body are not the same. The only way to truly know is to experience death. When a person dies their body stops functioning in all ways. Nonphysical things such as speech, memory, and emotion no longer have the other half, which was the living physical body to use.
What becomes of a person's memories and emotions can only be known by that person, since people do not come back from the dead. No one has ever experienced true death because death occurs when a person's physical body ceases to work. Although some parts of the body may work such as in cases of organ donation the complete physical body does not work. Death does not go on and off like a light switch in that it only happens one time to one person at a time.
Descartes' argument for dualism through his Argument from Divisibility is mostly based on faith and the assumption that the mind and body are different. If his idea was true then when a person suffers trauma to the head like in a car accident then that should not affect their mind and the way they think but there are many cases of people being permanently changed after head trauma. Another good example is the many prescription drugs that are out on the market such as Prozac. It is a pill which is a physical thing, like the body but it is proven to have an effect on the mind. According to Descartes the link between mind and body occurred in the pineal gland in the brain through a process called interaction ism but that theory does not make sense because the pineal gland is just another part of the physical body. In the end his argument cannot be true because there is no proven link between the mind and body.
There is just the physical body and nothing more; nothing less. Dualism is an idea mainly based on assumption and faith. Although it would be nice to know what happens to people after they die, that is something most people would like to wait to find out.