What philosophers call the mind body problem originated with Descartes. In Descartes' philosophy the mind is essentially a thinking thing, while the body is essentially an extended thing - something which occupies space. Descartes held that there is two way causal interaction between these two quite different kinds of substances. So, the body effects the mind in perception, and the mind effects the body in action. But how is this possible? How can an unextended thing effect something in space. How can something in space effect and unextended thing?
Cartesian dualism, and the general problem of the relation of the mind to the body, is a subject which aroused considerable controversy as soon as Descartes' Meditations started to be circulated. There are really many issues here, and as a consequence focus is a particularly difficult problem. One place to start is to read the article on "The Mind Body Problem" in the Encyclopedia of Philosophy, editor, Paul Edwards. I offer a Philosophical Problem connected with this issue in the Descartes file.
Here are some possible ways to narrow the scope of your
paper should you wish to pursue this issue:
(a) Focus your attention on Descartes' arguments in the
sixth Meditation for the real distinction between the mind and
the body. Go to the Philosopher's Index and look
for articles which focus on just those arguments. With a little research
you will find problems aplenty to occupy you just with one or the other
of these two arguments.
(b) Focus your attention on the problem of substances of
different kinds causally interacting with one another. The issue
in this sense might be put this way: Can the mind and
the body causally interact with one another if the mind is not
part of the physical system of the world?
Defenders of the view that the mind can interact with the
body include, of course, Descartes himself, as well as the
contemporary English philosopher C.D. Broad, in "The Traditional
Problem of Body and Mind" in his book Mind and its Place in
Nature. There is a reply to Broad by James Cornman "A
Nonreductive Identity Thesis about Mind and Body" in J.
Fineberg's Reason and Responsibility 4th ed. (see me for
a copy).
An author who gives a fairly good overview of dualism and
its problems, as well as alternative theories and their problems,
is Jerome Shaffer, in Philosophy of Mind,
Prentice Hall, 1968. Shaffer presents particular problems with
dualism such as:
(c) The problem of individuating immaterial substances.
How can you tell one immaterial substance from another?
(d) Descartes held that the body is basically a machine,
which is fundamentally different from the mind. He had various
tests which show that machines cannot think. This, of
course, raises interesting questions about artificial
intelligence and computers.
Many philosophers after Descartes proposed alternative
systems to avoid the difficulties of Cartesian dualism, including
Spinoza, Leibniz and others. You might wish to explore
Spinoza's criticisms of Descartes on substance, and the
alternative he proposed. You might start with Cottingham's book
The Rationalists. Then there is Roger Scruton's book
Spinoza and the Encyclopedia of Philosophy
article on Spinoza and the Philosophers Index. There
are good comentaries on Spinoza by Wolfson, Curley and Bennett.
I would follow the analogous procedure for Leibniz.