Descartes’ theory of Dualism asserts that everything in the universe is made of either mind or body. In other words, mind is one of the essential substances that make up reality, and body is the other. However, Descartes believed that human beings are composed of both, which is why it is called dualism.
Descartes said that what one knows best about ourselves is our own mind: “I am, I exist as a thinking thing.” Mind is not synonymous with brain, because brain is a physical thing, and the mind not physical, because it is separate from the body. The essence of the mind is thinking. The mind is indivisible and takes up no space. On the other hand, the body is physical, extended (takes up space), divisible, and unthinking. These are two separate substances, and yet humans are made of both. This leads to the mind body problem.
Since the mind affects and influences the body (they interact), and vice-versa, the term interactionism is used. The mind body problem holds that since the mind and body are defined as separate substances, they should not be able to interact with one another, according to the definition of the word “substance.” A substance can share no attributes (necessary qualities) with any other substance.
Descartes attempted to solve the mind body problem by saying that the mind and body actually come together in a place called the pineal gland (also known as the seat of the soul). Supposedly, the pineal gland is home to very fine humors. The mind acts upon the humors, and in turn the humors eventually act upon the body. This does not really solve the mind body problem. In my opinion, it only adds to the confusion. However, I agree with Descartes assumption that humans are made up of both body and mind, even though the body mind problem is still an issue.
To be totally honest, I ended up agreeing with dualism by default. I think the whole concept of subjective idealism is makes a lot of sense, but I would also like to think that things exist outside of my mind, and that idea is incompatible with idealism. Idealists believe that everything exists in the mind (there is no body).
On the other end of the spectrum, there are materialists, or those who think that minds do not exist. I tried to have an open mind when reading about these theories, but there are some things about materialism that I just cannot accept. I like the idea of “thinking bodies” because that would mean that matter can think, but as a psychology major I can provide more evidence for the premise of dualism/interactionism.
The mind can and does affect the body. There’s a whole science devoted to that assumption. For example, when a person is under a lot of stress (which affects the mind), certain reactions occur in his/her body. Sometimes stress can cause a person to get a headache (which affects the body, but was brought on by the stress in the mind). Similarly, if a person’s body is in pain, s/he will probably not be in a very good mood (state of mind).
Then there is the idea of mind over matter. I’m not referring to bending spoons or anything like that, but I know that the mind can affect matter/body. I have seen the effects of this when my cousin’s dog Alex had a false pregnancy. She wanted to have a puppy so much, that her mind (even though Descartes believes that animals don’t have minds!) convinced her body that she was pregnant. Alex began to produce milk and gain weight. She treated her stuffed monkey toy like a puppy and would not let anyone near it. Alex’s mind believed she was pregnant, so her body reacted accordingly.
In conclusion, I agree with most of Descartes’ theory of dualism. Even though the body mind problem still exists today, there might eventually be a solution to it.