Mind/Body Dualism: Two Together or One in the Same?

Descartes proposes that his mind and body are seperate entities that are in independent of each other but united in him. The body uses the faculties of sense and imagination to interact with the external world while the mind understands and makes judgments, which is to affirm or deny ideas. He reasons the two are separate in that: 1) mind is indivisible whereas the body can be divided into parts 2) The mind can operate independent of most body parts (with the brain as an exception) 3) The body has an interface that communicates with the mind (nervous system). It is this mind/body union that Descartes uses to restore the credibility of the physical world. The body uses its senses to inform the mind of bodies that must exist, since they indeed produce a sensation, and the mind wills which bodies should be desired or avoided. The cooperation of body and mind to pursue pleasure and avoid pain is the work of God's goodness, according to Descartes, and must be true.

This account of Mind/Body dualism is very alluring. Based on experience, it makes sense. One learns not to touch a stove by burning their hand. One knows when to eat when hunger is felt. In terms of thinking, forming ideas, judgments, etc. one doesn't necessarily use his/her entire body to do so. But can Mind and Body really be separate entities? Can one exist without the other? Or is it that the mind is simply a sophisticated feature of humans, but still bound by mortal flesh? The mind, as powerful as it can be, cannot live beyond the body because it is part of the body (the brain); it is not a separate entity.

The sciences have observed just how much the mental lives of people are tied to the brain. Different parts of the brain serve different functions. Sensation, perception, judgments, all the aspects of the mind, have been tied to parts of the brain. It has been shown how damage to the brain affects the performance of the mind.

How, and where, can a mind exist without a body? There has yet to be a credible account of someone having ideas and making judgments after their body has perished. Would that be the equivalent of a ghost? Descartes says he exists because he is a thinking thing, which is true. His body IS the thinking thing.

Perception and Object Perceived

For us particularly the empirical view that sensations resemble their causes is perhaps more common sense than it had been for Descartes. That is, it is common for most people to understand the general path of the object perceived to the sensation of a perception, in terms of the objects, light and machinery of the eye involved.  We learn about this in grade school.  Yet the question is why we come to believe that our perceptions resemble the things which cause them. To see the difficulty here, we must first acknowledge that perceptions are non-extended, to use Descartes’ language, beings purely of thought.  Moreover, every part of conscious existence is non-physical, to use our language.  And yet physical or extended things have an existence completely separate from our thought. The chair does not require my perception or consciousness in order to exist, whereas without my consciousness, there can be no perception. That is our first clue that the perception and the thing perceived are different in kind.

Once we grant that premise, we must ask why a conscious perception must resemble the object perceived. Let us say, for simplicity’s sake, that we believe there is a causal relation between the perception and the thing perceived.  The question remains why these things different in kind should have a relation of resemblance. Since they are different in kind, it seems doubtful that such a relation should exist. This would require us to explain why something that is different from another thing is transformed in kind, but in such a way that it may still resemble the original.  For that matter, how do we even explain resemblance between differences in kind?  Why would we say that the portrait of a person resembles that person? The portrait is two-dimensional and presents that person from a single point of view. Whereas the person is three-dimensional, by no means limited to the place in which the portrait is set and visible from a practical infinite points of view.

These are the matters than concern Descartes when he shows that a tickle does not resemble the feather than causes the sensation, nor a word the thing that is signified by it (“The World …”, 31). Given these purely conventional and non-essential relations, why do we cling to our common sense notion that perceptions resemble the objects perceived?