What is the mind-body problem, and what are the main positions?

The mind-body problem is the problem of explaining how the happenings of our mental lives, such as thoughts, feelings and experiences, are related to physical states, events and processes. Proposed answers are usually sorted into two broad families. Dualists hold that the mind is a different kind of thing from the physical. Physicalists hold that the mind is constituted by physical things, and for many of them the mind just is the brain. [1] [2]

Dualism says the mind cannot be reduced to something merely physical. A common way of putting the point is that scientists can observe your brain with methods such as functional magnetic resonance imaging, but they cannot observe your thoughts, which seem accessible directly only to you. The classic version is associated with the 17th-century philosopher René Descartes. [2]

Dualism has several varieties. Substance dualism says mind and body are different substances, while property dualism says mental properties are different from physical ones even if they belong to physical things. Interactionism holds that physical and mental states affect each other in both directions. Epiphenomenalism holds that physical states affect mental states but not the reverse. One overview notes that popular religious views of the mind are also usually a form of substance dualism. [3] [4]

Physicalism, also called materialism, holds that mental states are ultimately nothing over and above physical states. Its supporters often appeal to Ockham's razor: if brain function can explain mental phenomena, adding a separate nonphysical mind posits an unnecessary second kind of thing. The identity theory says mental states are brain states, so that feeling pain and a certain brain state are one and the same. Functionalism, a descendant of behaviorism and the identity theory, says mental states are defined by the role they play in a cognitive system. Some versions identify mental states with the functional states, others with whatever physical states fill that role. Because of this, functionalism allows minds in systems other than human brains, such as animals or computers. [1] [2] [3] [4]

Philosophical behaviorism treats mental terms as shorthand for an organism's behavior in its environment. Idealism, associated with George Berkeley, reverses the physicalist order and holds that physical states are derivative of mental ones. [4] [3]

The problem is better seen as a set of problems tied to each view. For dualists it is the interaction problem: how a nonphysical mind could relate to physical brain processes. For physicalists it is the so-called hard problem: how conscious experience can be nothing other than brain activity. Two features of minds, original intentionality (having meaningful thoughts) and qualia (the qualitative character of experience), are described as especially resistant to physicalist explanation. [2]

On which side has the stronger standing, one review says physicalist solutions have been dominant over the last century, with the exact variety, reductive or nonreductive, depending on philosophical arguments and on developments in the cognitive and neural sciences. Another source says neuroscience makes it increasingly plausible that the mind is in some sense identical to the brain. The results do not settle the question, and dualist and other views remain in the literature. [1] [2]