n.
In philosophy of mind , a species of mind-body dualism that holds that mind and body, though separate and distinct substances, causally interact.
Interactionists assert that a mental event (as when a person forms the intention to put his hand in a fire) can be the cause of a physical action. Conversely, the physical event (his hand coming into contact with the fire) can be the cause of a mental event (his feeling an intense pain). The classical formulation of interactionism is due to René Descartes , who could not satisfactorily explain how the interaction takes place, apart from the speculation that it occurs in the pineal gland. This problem led some philosophers to deny that mind and body really interact and to explain appearances to the contrary by appealing to divine intervention to create mental or physical effects for physical or mental causes (see occasionalism ) or to a divinely ordained "preestablished harmony" between the courses of mental and physical events. Benedict de Spinoza argued for a monistic theory on which mind and body were both attributes of a single underlying substance. See also dualism ; mind-body problem .