In his Meditations on First Philosophy, Descartes states “I have a clear and distinct idea of myself, in as far as I am only a thinking and unextended thing, and as, on the other hand, I possess a distinct idea of body, in as far as it is only an extended and unthinking thing”.  The concept that the mind is an intangible, thinking entity while the body is a tangible entity not capable of thought is known as Cartesian Dualism. The purpose of this essay is to examine how Descartes tries to prove that the mind or soul is, in its essential nature, entirely distinct from the
body and whether or not he is successful. While I agree with his theory that the mind and body are distinct, I do not believe the mind is non-extended and I do not agree with Descartes’ assertion that the mind is capable of existence beyond the body.
One of the ways in which Descartes attempts to prove that the mind is distinct from the body is through his claim that the mind occupies no physical space and is an entity with which people think, while the body is a physical entity and cannot serve as a mechanism for thought. 
I believe most of this portion of his position to be true. The body quite certainly has a physical presence and is not capable of controlling or thinking for itself. I begin to disagree with Descartes’ theory at the point where he states that the mind is non-extended. The mind is assuredly capable of thought, as Descartes states, and has intangible elements in the form of memories and personality characteristics; however, I believe that the mind is an extended entity because physical matter is required for these elements to exist. In my opinion, this means that the only logical conclusion is that the brain is the physical extension of the mind. Although the intangible elements of the mind are not quantifiable entities that can be measured on a physical scale, the brain most certainly is. Without the quantifiable entity that is the brain, the mind would have no medium for which to exist.
One, such as Descartes, might argue that because the brain has a physical presence, it is solely an entity of the body; the mind consists only of the intangibles. My response to such a statement is that because the mind exists only in the synapses that comprise the brain, the mind and brain are inseparable and therefore a single entity. Moods and complex emotions are heavily influenced by physical properties of the brain, such as the levels of certain chemicals. The loss of certain components of the brain can lead to an alteration of the mind as well. For example, Alzheimer’s disease causes dementia, a severe alteration of the mind, by destroying certain neurons and synapses. No other organ or appendage of the human body possesses this quality. The removal of a spleen or loss of a limb cannot permanently alter the mind on a primary level.
One might also argue that if a person does not have to consciously think about an
activity, it must be a function of...