Functionalism
Overview
Functionalism in the philosophy of mind is the view that a mental state is defined by what it does: by its causal relations to sensory inputs, to behaviour, and to other mental states. Pain is whatever state is caused by injury, causes avoidance and distress, and interacts with belief and desire in the characteristic ways, regardless of what that state is physically made of. The view was developed by Hilary Putnam in the 1960s on the analogy of a computer program, which is defined by what it computes and not by the hardware it runs on, and it is the mainstream position in the field.
Notes
- The standard objections are John Searle's Chinese Room, the "absent qualia" worry that a system could have all the right functional states and no experience (Philosophical zombies), and the "China brain" (a billion people with radios implementing one mind, which the objector finds absurd). The last is a straightforward argument from incredulity, and I think the first two fail for the reasons given under their own notes.
- My position under Consciousness is compatible with both functionalism and identity theory, and I said there that I did not need to settle the dispute between them. Substrate Independence settles it: I hold that what a conscious state is, is its function, and so the same function in another substrate is the same state.
- Functionalism is not behaviourism. Behaviourism defined mental states by outward behaviour alone; functionalism includes the internal organisation, which is why a lookup table that produced the right outputs would not count as having the mental states and a system with the right internal structure would.