Plato Desartes Materialism
How is mind different from body? How do mind and body nteract? How is mind body?
Philosophers have proposed idealism, physicalism, behaviorism, and functionalism as responses to the mind-body problem.
Idealists take the mental to be the furniture of the universe. There is nothing for idealists beyond minds, ideas, perceptions, sensations, and other experiences. But with the success of twentieth-century science—including revolutionary discoveries of space and time, the subatomic world, genetics, and the biology of life—idealism seemed unscientifically esoteric and various forms of materialism seemed more promising.
Physicalism is a family of materialist positions claiming that the mental is to be understood entirely in physical terms. A common form of physicalism is identity theory—the theory that the mental is identical to the physical. Two variants are type-identity theory and token-identity theory. According to type-identity theory, any mental state, such as a belief, is identical to a particular brain state but it is unclear whether you always find identical brain states that constitute shared beliefs. Millions of people hold the belief that “the New Horizon spacecraft has passed Pluto,” but are all of those beliefs constituted by type-identical brain states? Type- identity theory doesn’t tell us what constitutive brain states to look for, so the question couldn’t be answered even if we had perfect knowledge of the brains of all of those millions of people. Moreover, some physicalists wanted to have more flexibility in terms of what could count as type-identical mental states. They thought that different physical structures could implement the same type-identical mental states.
Token-identity theory is more flexible, allowing that a type of mental state can be realized in different token brain states, including those of possible alien and artificial brains. It is, however, unclear what would make different physical states the same type of mental state. If I and an extraterrestrial feel the same type of pain, what physical fact would make it so? Our biological makeups could be entirely different! This problem drove some physicalists in the directions of behaviorism and functionalism.