In the Sixth Meditation, Descartes makes a bold claim to the separation of his mind from his body. Descartes bases this claim upon his usual foundations: indubitable certainties, word games, and his strong beliefs in God. But regardless of the truth of Descartes' argument, I feel that his proof is simply too vague and unfounded. In this paper, I will fully discuss Descartes' theory, his arguments, and why I do not feel that they are good arguments.
The section of text under examination is in the middle of the Sixth Meditation. Descartes' conclusion is that "It's certain, then, that I am really distinct from my body and can exist without it." (CSM pp. 54 – 55) This needs to be explained. Descartes has determined previously that "he" is his soul, his mind. Because "he" can perceive "himself" separately from "his" body, Descartes concludes that his mind and soul, that is, "Descartes" is not necessarily attached to or is dependent upon the physical body of Descartes.
Descartes bases this theory in his doubt of his senses. Descartes has decided not to trust what he perceives, because "from time to time [he has] found that the senses deceive, and it is prudent never to trust those who have deceived us even once." (CSM p. 17) Descartes claims that since he can dream of anything that he can sense, his senses are not necessarily founded in the material world. In addition, he has often found that his perception of an object is incorrect, or changes as his relationship to the object changes. He also points out that madmen have faulty sensory experiences, and suggests that God may be deceiving him or his senses. In contrast, Descartes states that what he understands through his reason, is both independent of the material world, and produces a much sharper image in his mind. (First Meditation)
Descartes feels that being able to "clearly and distinctly understand one thing apart from another" is sufficient to be certain that it is distinct from the other, since the things that could be separated, at least by God. (CSM p. 33) Descartes says he has a "clear and distinct idea" of himself that is a "thinking and non-extended thing." In addition, his understanding of his body is also distinct, but he sees it as an "extended and unthinking thing," so he must be separated from his body. (CSM p. 54)
Descartes provides further arguments for the separation of his mind and his body. He claims that because his senses often produce unwanted or undesired images, they cannot be a part of his mind. This is because he has full control of his mind, and he would not willingly experience unpleasant sensations. Therefore, his sense perception cannot come from his mind. (CSM pp. 52 – 53) Because he experiences the rationally undesirable, his senses must have nothing to do with his ability to rationalize. This also proves, according to Descartes, the existence of physical things, because the only ways his senses could perceive them would be if God were tricking him, or if the physical world exists. And "it is impossible that God should ever deceive me." (CSM p. 37) Descartes resolves the problem of communication between his mind and his body in a simple fashion. He determines that his mind is not present in his body. (CSM p. 59) This is problematic, for reasons that I will discuss later.
I do not believe Descartes' arguments are very strong. I agree with his premises, but I think that the manner in which he proves his premises and draws his conclusion from them is weak. His argument that his senses should not be trusted entirely is something that I agree with, but I disagree with his reasons. The fact that objects appear differently from dissimilar vantages is a problem with physics and optics, not with the senses. The senses are generally accurate; however, if the information going to the senses is faulty (say, through a mirage) it will seem as if the senses are to blame. However, Descartes uses this as an example of his senses tricking him. The second argument against senses, the dream argument is also faulty. Dreams are not sensory perception; they are imagination. As Descartes would say, dreams are a product of himself applying his reason to objects that he has already observed, imagined, or envisioned in his mind. Since dreams are not very similar to sense perception (even those dreams that seem very real are quickly discovered to be dreams), it does not make sense to accept them as proof of the invalidity of the senses. His third possible source of faulty experience, God, is dismissed as not possible. But his proof of God rests upon his distrust of the senses, which rests upon the existence of God. So Descartes' logic is not very strong for this argument.
Why does he use God in this manner, and why is his argument circular? God must play a role in his argument, because he attributes God as being a potential source of his sensory perception. Furthermore, he proves his argument by eliminating the two competitors to the physical world as the source for his sense perception, the imagination and God. The elimination of his imagination is, as stated before, weak. So Descartes must find a way to get rid of God as being a source of his experiences. His proof of God presupposes that his senses cannot be trusted, based on the following arguments: many people have false perceptions, dreams often seam to be real, and God could be deceiving him. By discounting the value of sense perception, Descartes says that he can only trust his own "clear and distinct" thoughts. One of his "clear and distinct" thoughts is that God exists, that He is perfect in every manner, and that he is good in every way. (CSM p. 28) Because God is good in every way, He would not deceive Descartes. Unfortunately, his conception of "clear and distinct" thought relies on his version of God (if God was a deceiver, He might decide to trick Descartes into having "clear and distinct" thoughts). Unfortunately, this leads Descartes into a circular proof of God, so we cannot trust his elimination of God as being proof of the physical world; after all, God just may be a deceiver who has put these "clear and distinct" thoughts into Descartes' mind. And, "I see plainly that the certainty and truth of all knowledge depends uniquely on my awareness of the true God…" so the knowledge that "clear and distinct ideas" are infallible must rest upon the proof of God. (CSM p. 49)
But let us assume that Descartes has proven his version of mind-body dualism. How would it work? Descartes provides two different versions of how mind-body dualism could work. The first is called "The Natural Institution Theory." In this version, the mind is completely incorporeal, and communicates with the body through the pineal gland (Descartes does not seem to offer any good reason why the mind would communicate through the pineal gland as opposed to, say, the big toe on the left foot). Through this interaction, the mind gets feedback from the body and sends commands to the body. The second version, the "Co-extension Theory" holds that the mind is present throughout the body, just as like bubbles in soda. Because the mind permeates the body, it is able to communicate with the body.
In the "Natural Institution Theory," the mind experiences bodily sensations in what is called the "Cartesian Theater." In the Cartesian Theater, the mind receives signals from the body, and the signals are reenacted, in a fashion, by the mind. The "mind's eye" views these actors on the stage, interprets their actions, and processes the information. Therefore, every sensation, thought, idea, etc. has some sort of brain state associated with it. And God has predetermined exactly what kind of thoughts correspond with each brain state, just as every x has one, and only one corresponding y in a mathematical function. On the other hand, the "Co-extension Theory" creates a third entity, the "mind-body union." This is the source of physical sensations.
This is a marvelous tale, but it is pure fantasy. Not only do either of these theories make much sense (they do seem rather mystical), but they do not stand up to the test of logic either. Let us examine each of these three ideas to see what is wrong with them.
In the "Natural Institution Theory," the weak point is the link between the mind and the body, in the pineal gland. Gassendi makes a good objection to this idea: "how can contact occur without a body?" If the mind is incorporeal, how does it communicate with the corporeal pineal gland? Some part of the mind must be physical for this to happen, or some part of the pineal gland must be immaterial. Therefore, either the mind is not completely incorporeal, or the body is not completely physical. (CSM p. 239) In addition, if your mind were completely incorporeal, it would be impossible for you to have any ideas about material things, because your mind would not understand them at all. (CSM p. 234) The Cartesian Theater has problems as well. If there were one, and only one predetermined brain state for each thought, experience, idea, etc., there would have to be an infinite number of brain states. In fact, there would have to be infinite brain states just for all of the colors! I find it hard to believe that there are an infinite number of brain states that God has predetermined for every person who has ever and will live. Additionally, the very idea of brain states assumes that the mind is a physical entity; otherwise it could not have states to be in. Furthermore, the idea of "actors" performing for the "mind's eye" is ridiculous. This sounds as if there are physical objects within the mind acting out parts for a sensory organ within the mind, making the mind a physical object after all. Although this does explain imagination, dreams, and so forth, it creates yet another problem: who is viewing the mind's eye? It seems as though the mind's eye would need an infinite number of eye watching eyes watching eyes, etc., like the Land O Lakes butter packages.
The "Co-extension Theory" is just as weak. As Gassendi points out, it is impossible for Descartes to declare that his mind is a thinking, non-extended object while it is also pervasive throughout the body. (CSM p. 235) In addition, it makes no sense for the mind to be considered to be a whole while it is spread throughout the body. Another objection occurs to me: if the mind is spread throughout the body, why do people not lose parts of their memory or reasoning ability when they lose a limb? If the mind is spread throughout the body, then it makes sense that losing a finger might erase a few words from your vocabulary, the ability to play poker, and the names of your pets, whereas the loss of both legs would erase much more, for example, your ability to perform complex mathematics, a good portion of a language, and other major parts of your mind. Even Descartes says that this is not the case (CSM p. 59), so we can discount the "Co-extension Theory."
In light of these arguments, Descartes' mind-body dualism is severely flawed. I feel that it is telling that he has so many versions of all of his ideas (three proofs of God, two mind-body dualisms, etc.). He simply cannot get one right. The objections to Descartes are strong, and he only answers them by reformulating the same argument based on the same premises (which themselves are often severely criticized). In light of this, I simply do not think that Cartesian mind-body dualism stands a chance. There may be some hope for the separation of mind and body, but it does not come from Rene Descartes.
I have loved working with computers since I was a kid. I specialized in software development, but I also do a lot of systems administration and some network engineering. Currently, my development interests are in C#, parallel processing, and exploring business usage of dynamic and functional languages. In addition to my day job, I write for TechRepublic, primarily in the "Programming and Development" area, and ForMortals. I am currently (when time permits) working on a book that aims to teach new developers everything about how to write software, other than how to program in and of itself. In addition, I do a bit of software development under the banner of my own company, Titanium Crowbar Industries
I love learning about history and philosophy (I doubled majored in those subjects in college) as well. The essays on this site regarding those topics were all written by me in college and high school. I also am extremely interested in physical fitness, and devote a substantial amount of my time to weight lifting. I am currently focusing on lifting heavy weights and I have participated in a few powerlifting meets. Currently, my non-technical readings have focused on various religious ideas and fitness. I am a big fan of Phillip K. Dick and Frank Herbert, and both of those authors have shaped my worldview greatly.
You can also find me on Facebook.