Dualism

What is the relationship between the mind and the brain?  Monists believe that there is only one substance or property in the Universe, be it physical (Materialists) or mental (Idealists).  But Dualists, like the 17th Century French philosopher Rene Descartes, hold that mental stuff exists side by side with physical stuff.  Can this view be defended, in light of modern science?  John and Ken probe the mind-body with David Rosenthal from City University of New York, author of Consciousness and Mind.