Cartesian Dualism and Its Interaction Problem

René Descartes gave the mind-body problem its canonical modern form in the Meditations on First Philosophy (1641), arguing from the method of doubt that he could conceive of his mind existing without his body but not without thought, and concluding in the Sixth Meditation that mind (res cogitans, an unextended, thinking substance) and body (res extensa, an extended, non-thinking substance) are really distinct — two fundamentally different kinds of substance, each capable in principle of existing independently of the other. This position, substance dualism, holds that a human being is a composite of two ontologically separate things: a body that is a mechanism obeying the same laws of extension and motion Descartes had laid out in his physics, and a mind whose essence is thought (cogitatio), encompassing not only reasoning but sensation, imagination, and volition. Descartes took non-human animals to be mere automata, complex machines without thought or feeling, a striking consequence of restricting mentality to substances possessing an immaterial soul, which he reserved for humans alone on largely theological and introspective grounds.