Physicalism and the Identity Theory
Physicalism holds that everything, including the mind, is ultimately physical; the identity theory is its claim that mental states just are brain states.
Definition
Physicalism is the thesis that everything is physical or supervenes on the physical; the mind-brain identity theory is the specific physicalist claim that mental states or types are identical to physical brain states or types.
Scope
This topic covers physicalism as a general metaphysical thesis and its principal versions concerning the mind: type and token identity theories, reductive and non-reductive physicalism, and eliminative materialism. It addresses the arguments for taking the mental to be wholly physical and the objections, especially multiple realizability, that motivate refinements.
Core questions
- Is every mental state identical to some physical state of the brain?
- Should identities be drawn at the level of types or only of tokens?
- Does the multiple realizability of mental states refute the type identity theory?
- Are some folk-psychological mental categories candidates for elimination rather than identification?
Key concepts
- type identity
- token identity
- reductive physicalism
- non-reductive physicalism
- eliminativism
- multiple realizability
Key theories
- Type identity theory
- Each type of mental state is identical to a type of physical state, defended by appeal to the parsimony and explanatory power of treating sensations as brain processes.
- Eliminative materialism
- Folk-psychological posits such as beliefs and desires may not map onto anything in a mature neuroscience and could be eliminated rather than reduced.
History
The identity theory was introduced by Place (1956) and developed by Feigl and Smart (1959), proposing that mental states are contingently identical to brain processes. Putnam's multiple realizability argument prompted a shift toward token identity and functionalism, while Churchland (1981) pressed the more radical option of eliminating folk-psychological categories outright.
Debates
- Multiple realizability
- Whether the fact that the same mental state can be realized by different physical systems refutes type identity in favor of token identity or functionalism.
- Elimination versus reduction
- Whether folk-psychological states should be reduced to neural states or eliminated as a defective theory.
Key figures
- U. T. Place
- J. J. C. Smart
- Paul Churchland
- Jaegwon Kim
Related topics
Seminal works
- place1956
- smart1959
- churchland1981
Frequently asked questions
- Does physicalism deny that minds exist?
- No. Physicalism holds that minds exist but are wholly physical; only eliminative materialism, a stronger view, denies that certain mental categories pick out anything real.