IB Philosophy 10.3.5 Mind–body Dualism Key Definitions

The conceivability principle holds that if something is clearly and distinctly conceivable, then it is genuinely metaphysically possible. Descartes uses this principle to argue for substance dualism, reasoning that because he can clearly conceive of his mind existing without his body, the two must be distinct substances capable of existing independently.

Functionalism is a theory of mind holding that mental states are defined by their causal roles rather than by the physical substrate that realises them. According to this theory, what makes something a mental state is the functional role it performs in mediating inputs, outputs, and other mental states, not whether it occurs in neurons or silicon.

Physicalism is the metaphysical position that everything that exists is physical or depends entirely on the physical. Applied to the mind-body problem, it holds that mental states are identical to, or wholly determined by, brain states, encompassing both the identity theory (mental states just are neural states) and eliminative materialism (folk psychology will eventually be replaced by neuroscience).

Property dualism holds that while there is only one kind of substance (physical), conscious experience involves non-physical properties that cannot be reduced to or fully explained in physical terms. David Chalmers defends this position through the hard problem of consciousness, arguing that subjective experience resists any purely physical explanation.