Dualism

Dualism is a family of philosophical theories that hold that there are two kinds of substances or properties that constitute reality. In common discussions, these are mind or mental phenomena (such as consciousness, thoughts, and feelings) and matter or physical phenomena (such as bodies and brain processes). The term is most closely associated with the view that mind and body are distinct in nature.

Historically, dualist ideas are strongly linked to René Descartes, who argued for substance dualism. He proposed two distinct substances: res cogitans, a thinking, non-extended substance, and res extensa, an extended, physical substance. According to Cartesian dualism, mind and body can interact causally, though they are ontologically different. The broader lineage of dualistic thinking also appears in earlier and contemporaneous religious and philosophical traditions that have posited a separable soul or non-physical aspect of reality.

Variations within dualism include substance dualism, which posits two kinds of substances, and property dualism, which holds that there is a single physical substance with non-physical properties. Within substance dualism, theories differ on how mind and body interact: interactionism allows causal influence between mental and physical states; parallelism suggests they run in parallel without causal interaction; occasionalism attributes coordination to a divine cause.

A central challenge for dualism is the problem of causal interaction: how can non-physical minds causally affect physical bodies without violating physical laws? This has led many philosophers to adopt physicalist or monist alternatives, though dualist positions continue to be explored, especially in discussions of consciousness, personal identity, and the nature of experience. Contemporary debates often distinguish between substance dualism and property dualism or nonreductive physicalist positions.