Ryan asked:

How does an immaterial mind move a material body? I feel that Descartes does not give an adequate
answer in his letter to Elisabeth. How does the soul interact with the body or does it?

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Given the formulation of the issue, perhaps Descartes' reply is the best that can be provided. The
reply seems to be that indeed, it is difficult to see how what is immaterial and non-spatial can interact
with what is material and spatial, but that it is a matter of ordinary experience that it happens, so
perhaps we had better leave it at that. You should notice how un-Cartesian this answer is for a
philosopher who customarily disdains "ordinary experience." (Although, it was just this sort of reply
that the empiricist Hume, who while he did not allow that mind and body were two different
substances, did accept. Hume agreed that mental and physical events did interact and gave that
interaction as an illustration of his view that for all we can know a priori, "anything can cause
anything.")

I said that given the formulation of the issue, Descartes' reply to Elizabeth might be the best reply that
can be had. What I meant is that the unsatisfactoriness of the reply, which you recognize, might be
taken as a reason to revisit the terms of the issue, and, in particular, to question Cartesian dualism.
Are indeed mind and body two substanceswith the opposite characteristics Descartes describes
them as having? Perhaps we should look for a different concept of mind which does not have the
problems of Cartesian dualism. There are several of them out there. Gilbert Ryle's analytical
behaviorism, and various form of the mind-brain identity thesis, as well as functionalist views.

Kenneth Stern

Descartes cannot prove that an immaterial substance interacts with material substance since we
have no idea of how such a substance would be able to interact with spatial substance which falls
under physical laws. It follows from Cartesian dualism that if the mind is distinct from the body, which
includes the brain, no account be given of why mental impairment results from brain damage. That
brain damage does affect the mental can support a claim that there is physical-to-mental causation if
you want to maintain that the mental is distinct from the physical, but it doesn't work the other way
around.

Rachel Browne