But not even an evil genius could deceive someone into believing falsely that he existed. Descartes is known as the father of the mind-body problem. He claimed that human beings are composites of two kinds of substances, mind and body. A mind is a conscious or thinking being, that is, it understands, wills, senses, and imagines. A body is a being extended in length, width, and breadth.
Minds are indivisible, whereas bodies are infinitely divisible.
Despite having different natures, Descartes thought that mind and body causally interact. The human mind causes motions in the bodies by moving a small part of the brain. Motions in that same part of the brain produce sensations and emotions. This problem of whether mental entities are different in nature from physical entities continues to be a primary concern of philosophers and psychologists. Descartes argued that bodies differ from how they appear through senses.