Descartes argument for dualism Descartes has shown in meditation 2 that he can understand himself purely as a thinking thing In meditation 5 he has shown that he can understand bodies purely in terms of their spatial, extended characteristics Whatever can be understood clearly and distinctly as distinct really is distinct Therefore there is a real distinction between mind and body.

Is it true that we can understand our minds independently of anything physical? Is it true that whatever we can understand as distinct is really distinct? Lightning is identical to an electrical discharge, but it was a scientific discovery that these “two” things were really one. Could the same be true of mind/body?

Another argument for dualism Physical things are spatially extended (have a certain size, exist in space) Minds have no spatial extension Whatever is identical must have all properties in common. Therefore minds and bodies are distinct things.

The Mind/Body Problem Descartes is an interactionist dualist. He believes that there is causal interaction between minds and bodies. When I move my hand my mind causes my body to move. When I stub my toe, my body causes my mind to experience pain http://prosblogion.ektopos.com/

It’s hard to understand how interaction is possible It seems that when two things causally interact, they must share a common medium, they must be able to “meet up” somehow One billiard ball can cause another to move only because they are both in space and can touch each other The Moon and Earth do not touch, but they share the medium of space. Even “action at a distance” presupposes a common medium

But if the mind is not in space, it cannot meet up with the body, nor is it possible for anything physical to come into contact to the mind. Therefore (the critic argues) dualism leads to the conclusion that mind body interaction is impossible But this is crazy—therefore there is something wrong with dualism

Dualist Responses Causal interaction is in general mysterious. There is no special problem for mind/body interaction Just because we do not understand how mind/body interaction can work, does not mean it cannot work (see above) experience teaches they do interact.

Another mind/body problem It is a presuposition of science that the physical world is causally closed. This means that the cause of every physical event (if it has a cause) is also something physical. But interactionist dualism denies this. If interactionist dualism is true, there are some events in the brain that are caused by a non-physical thing, the mind.

Alternatives to substance dualism Materialism: If the mind identical brain processes, there is no mind/body problem, since the mind itself is something physical. Idealism: If matter is it itself mental or mind dependent, again no mind/body problem

Alternative versions of dualism Property dualism: there is only one kind of thing (matter) but this thing sometimes has mental properties Epiphenomenalist dualism: The body interacts causally with the mind, but not vice/versa. Mental states are byproducts of brain activity (like car exhaust)