Substance dualism

Substance dualism, in its classic Cartesian form, holds that mind and matter are two genuinely distinct kinds of substance — a physical body governed by physical law, and a non-physical mind or soul that thinks, feels, and wills — related and causally interacting, but neither reducible to the other.

Its appeal is that it takes the felt distinctness of consciousness at face value rather than explaining it away: pain does not just correlate with nerve firing, it is a different kind of thing from nerve firing. Its standing cost is the interaction problem Descartes's own contemporaries pressed on him almost immediately: if a non-physical mind has no physical properties (no mass, no location, no physical causal powers), how does it move a physical body without violating the physical conservation laws that govern every other causal interaction physics knows about?