Alvin Plantinga is an American philosopher, currently the John A. O'Brien Professor of Philosophy at the University of Notre Dame. He is known for his work in epistemology, metaphysics, and the philosophy of religion, and in particular for applying the methods of analytic philosophy to defend Christian belief.

In this clip, he argues for the ontological distinctness of mind and body on the basis of modal properties and the identity of indiscernibles (i.e. Leibniz's law).

http://en.wikipedia.org/wiki/Alvin_Plantinga

http://plato.stanford.edu/entries/dualism/#ModArg

http://en.wikipedia.org/wiki/Identity_of_indiscernibles