Descartes's argument for material things and mind-body distinction

¶ … Descartes successful in showing that "the existence of material things, and the real distinction between mind and body?" (Meditation VI)

Descartes Meditation IV: Was Descartes successful in showing that "the existence of material things, and the real distinction between mind and body?" (Meditation VI)

Perhaps one of the most difficult arguments for a reader to accept, given modern innovations in science and medicine is Descartes' argument in "Mediation VI" that the philosopher himself is distinct from his body and can exist without his body and the idea of "thinking body" is simply self-contradictory. Immediately, stroke victims whose ability to recall past memories come to mind, or the personality-erasing quality of Alzheimer's disease, as well as the effects of a blow to the head or brain surgery upon the personality, or even the temporary effects of drugs. But Descartes himself acknowledges the reality of illnesses that can disturb the sensory perceptions of the 'owner' of the body. He asserts, however, given the strange, interconnected nature of the relationship between the mind and the body, it is possible that the body will sometimes send false messages to the mind.

This explains the false pains experienced by amputees and conditions like dropsy, where the afflicted continue to drink and, because they are misled by the symptoms of thirst or a need for their beverage of choice, and eventually die from the disease of over-drinking. (61) Thus, it may be said that Descartes systematically proves the mind/body split and the existence of material objects, but only in the narrow terms by which he sets his debate in the "Meditations." For a modern reader, the Christian and non-scientific (although mathematical) terms of "Meditation VI" will likely be unsatisfactory

The question of relationship between a mind and a body is critical to what Descartes means by a human being and the human condition within the framework of his philosophic, rationalist discourse. He asks the question of how can minds and bodies exist together, appear to be the same, yet operate in separate ways, and constitute separate material essences, in the sense that the body can err, but the mind is a product of God? Descartes' acknowledges the body's material existence, but how can the earthly, corporal being and the mind enter into a bond of causal interaction, so that the mind, for example, can perceive a ball heading to the head and the hand can catch the ball? The mind is pure thought and the body is pure motion, so how can the mind urge the body to catch the ball in motion, by moving the body's hand with the mind? This is what has been called the mind/body problem of modern, Western, particularly modern, Western Christian philosophy that presupposes a good, non-deceitful God that created a good material world, yet sees the mind or essence of the human being as above the body and aligned with the soul.

Descartes' dualistic argument is that he knows clearly and distinctly that he is a thinking being -- going back to his first meditation's most famous argument and quotation of Descartes that 'I think therefore I am.' But Descartes' idea of the body is different from modern notions, namely his idea of body is incompatible with the process of accurate thinking, which takes place outside of the sensory realm. In Descartes' mind, true thought must be free of doubt. In fact, of the medical examples cited above, Descartes would state this only affirms the doubt inherent in the sensory aspect of human bodily actions, but not the human mental condition. Because Descartes will allow only what he cannot doubt, the fact that the ordinary senses can be damaged or are simply liable to error is proof positive of the body's inaccuracy. The objects of the senses "may not all exist in a way that exactly corresponds with my sensory grasp of them, for in many cases the grasp of the senses is very obscure and confused. But at least they possess all the properties which I clearly and distinctly understand, that is, all those which, viewed in general terms, are comprised within the subject-matter of pure mathematics," unlike the comprehensions of the body. (55).

In "Meditation VI," Descartes gives the example of white object that appears, but is not 'really' red if a red light happens to be illuminating the white area as an example of how the senses can play the owner of the bodily senses false. Also, person cannot tell what he or she is eating, or cannot tell if food is superior or spoiled if the person has a cold -- or has lost his or her sense of taste or smell through trauma. Descartes concludes that he can know the material world with certainty only as it is the object of pure mathematical study, in the sense that it can be confirmed with objective calculation and data. Such objectively measurable properties of things are the size, shape, and weight of objects vs. subjective or non-mathematically quantifiable properties like color, smell and taste. For example, one can say that a gram of a particular kind of spice is pungent or not pungent, depending on one's taste, but one cannot deny that it weighs a gram.

This is why Descartes begins "Meditation IV" by quoting the words of the last meditation, "Meditation V" on: material things that "are capable of existing, in so far as they are the subject matter of pure mathematics, since I perceive them clearly and distinctly. For there is no doubt that God is capable of creating everything that I am capable of perceiving in this manner; and I have never judged that something could not be made by him except on the grounds that there would be a contradiction in my perceiving it distinctly." (50) A contradiction or a subjective doubt invalidates the proposition of objective existence. Imagination and our senses merely create the illusion of the mind as united with the body intrinsically.

True, we have a sense of our bodies, as material properties. "On the one hand, I have a clear and distinct idea of myself, insofar as I am simply a thinking, non-extended thing; and on the other hand, I have a distinct idea of body, insofar as this is simply an extended, non-thinking substance. And accordingly, it is certain that I am really distinct from my body and can exist without it." (54) In other words, we have a sense of ourselves as bodies, Descartes asserts -- but as bodies that are fundamentally non-thinking beings. A questionable assertion at best, one might say, although it is true that people who have lost certain senses or aspects of their personality as the result of trauma do not perceive this immediately. Regardless, sensory ideas are produced without my cooperation and often against the will -- the taste of a pungent spice, thus the sense does not come from within, it must be a formal reality, unless it is a false idea, which is impossible, as God is not a deceiver.

However, to use Descartes analogy of the body and the mind as like a ship piloted by a human intelligence, the existence and sense of material bodies that is not deceit does not mean that body and mind are of the same substance, even if both exist, rather one is always inferior and separate from the other, although extant: "I am not merely present in my body as a sailor is present in a ship, but that I am very closely joined and, as it were, intermingled with it, so that I and the body form a unit. If this were not so, I, who am nothing but a thinking thing, would not feel pain when the body was hurt, but would perceive the damage purely by the intellect, just as a sailor perceives by sight if anything in his ship is broken. Similarly, when the body needed food or drink, I should have an explicit understanding of the fact, instead of having confused sensations of hunger and thirst. For these sensations of hunger, thirst, pain and so on are nothing but confused modes of thinking which arise from the union and, as it were, intermingling of the mind with the body" (56).