The modern scientific consensus is that the ‘mind’ is just a word we use to describe our experience of our own brains in action. That is, mind and brain are more or less the same thing, just described at different levels (this gets stuck in the semantics because the brain monitors some nonconscious things such as heart rate, activities not normally thought of as in the domain of the mind).
Different people arrive at the hypothesis by their own paths. To me, the most compelling evidence is the range of bizarre consequences of brain damage. For instance, check out this late-December New York Times profile of a recent case of blind-sight, a phenomenon in which a person, due to brain damage, believes herself to be blind, but is clearly able to see. Oliver Sacks books are full of such cases, such as hemispheric neglect, in which people lose their awareness of half the world, to the extent that they eat from only one side of their plate, shave only one side of their face, and may even only be able to turn in one direction. A recent obituary of a famous amnesic noted how work with amnesics has shown that losing one’s ability to form memories is in essence losing part of oneself.
Data like these make it hard to save dualism. If there is a non-material soul, it is not responsible for memory, for having a sense of left or right, or probably even for consciousness itself. That doesn’t seem to leave much for the non-material soul to do. This conclusion may be disheartening, but it seems inescapable.
(Pictured borrowed from ReallyTinyBrain.org)