High Quality Content by WIKIPEDIA articles! The mind-body problem is a philosophical problem arising in the fields of metaphysics and philosophy of mind. The problem arises because mental phenomena appear to be qualitatively and substantially different from the physical bodies on which they appear to depend. There are a few major theories on the resolution of the problem. Dualism is the theory that mind and body are two distinct substances, and monism is the theory that mind and body are, in reality, just one substance. Monist materialists (also called physicalists) take the view that they are both matter, and monist idealists take the view that they are both in the mind. Neutral monists take the view that both are reducible to a third, neutral substance.