The Mind-Body Problem and Descartes

It is obvious that we have bodies. We spend a lot of time and energy on our bodies. We measure them, we observe them in mirrors. Even more we observe the bodies of others. We feed our bodies, we go to doctors to treat their medical problems.

            It seems equally obvious that we have minds. We study and travel to expand its experiences, we see specialists to cure its illnesses, pay attention to its beliefs, emotions, doubts, etc. We sometimes “speak our minds,” that is, express what is “on [in?] our minds.”

            Minds seem to be characterized by consciousness. What sort of thing is consciousness?

It seems to have three characteristics:

1) It is the awareness we have of ourselves and others when awake. We seem to lack it when sleepwalking, under anaesthesia, or knocked out.

            2)  Aboutness, sometimes called intentionality: consciousness is often about others, sometimes about ourselves, or about things around us, about things past, present, or possible in the future. We can even be conscious of mathematical truths that seem to be nonphysical, or of things like those that Plato had in mind when he spoke of the Forms for Beauty or Justice.

            3) Subjectivity. My consciousness is mine, private not public. We are immediately aware of our own consciousness . . . The “I” has privileged access to itself.

Consciousness cannot be observed by others. . . seems to have no weight, taste, color, mass, or dimensions.

            The view of human nature “obvious” to most of us is dualism:  Human nature consists of both mind and body, in short, dualism. (Still, for many dualists, such as Plato and Descartes, self-hood is more a question of the mind than the body.)

            As soon as we consider dualism, the following problem arises. Mind seems to affect body and vice versa. When does mind seem to interact with body?

When we feel pain or otherwise perceive that seems to be explained by the fact that something  has happened to the body, or when we decide to move a limb.

 Descartes “proves” the existence of a mind distinct from body.

• I can conceive that I do not have a body.

• I cannot conceive that I do not have a mind.

(Assumption: If I can conceive of one thing without another, then the two things are distinct.)

Therefore, mind is distinct from body.


The essence of mind for Descartes: Thinking


                                                    Types of thinking (examples)



imagining,                                                                                                                 getting angry,


disliking,                                                                                                                             fearing,


remembering,                                                                                                                   doubting,


believing,                                                                                                                        reasoning,




To have (or be) a mind at all, I must be thinking, not in every way but in some way.


Does that mean that we cease to exist when we are asleep but not dreaming?  It would mean that, says Descartes, but during our lives, it does not happen.  We do not necessarily remember when we wake up the thoughts were present in our minds during sleep.


The essence of body (according to Descartes)


Ability to fill a given space such that other bodies are excluded from it-- “extension”


Descartes is a dualist


He believes that humans are composed of two things, an “extended” physical body and an immaterial thinking mind.


The big problem for Descartes’ dualism was this: How can an immaterial mind (that Descartes denied had a location in space) move a physical body that does? How can a body consisting of space-occupying matter influence an immaterial mind?


Descartes’ “solution”: The two interact in the pineal gland, a small gland near the brain that had no other known function.


His solution was ridiculed. After all, the pineal gland is a body too. If we cannot explain how an immaterial thing can move a body, then to say that it moves a small body leaves the problem unresolved.