Cartesian Dualism and the Mind-Body Problem

Having secured the existence of the thinking self and, through the Third and Fifth Meditations' arguments for the existence of a non-deceiving God, the reliability of clear and distinct perception generally, Descartes argues in the Sixth Meditation for a real distinction between mind and body. His central argument runs that he can clearly and distinctly understand himself, as a thinking thing, apart from his body, and that whatever he can clearly and distinctly conceive as separate, God can indeed create as separate; therefore mind and body are really distinct substances, capable, at least by God's power, of existing apart from one another. In the Principles of Philosophy (1644), Descartes systematizes this into a doctrine of two created finite substances, res cogitans (thinking substance, whose principal attribute is thought) and res extensa (extended substance, whose principal attribute is extension in length, breadth, and depth), alongside the one infinite uncreated substance, God. This position, now generally called Cartesian dualism or substance dualism, holds that a human being is a genuine union of an immaterial, unextended mind and a material, extended body, rather than simply an especially complex machine, though Descartes elsewhere, in the Treatise on Man (written by the early 1630s but published posthumously in 1662 for fear of ecclesiastical condemnation after Galileo's 1633 trial), treats the animal and human body itself as governed by mechanistic principles, with the nonhuman animal body operating, in his view, as an automaton entirely without a thinking soul.