View source for Multiple Realizability

'''Multiple realizability''' is the philosophical thesis, most associated with Hilary Putnam, that a given mental state or cognitive function can be implemented by many different physical systems. Pain in a human, pain in an octopus, and pain in a hypothetical silicon organism are all realizations of the same mental kind — pain — despite being implemented by radically different physical substrates.

The argument was directed against [[identity theory]], which held that mental states are identical to specific neural states. If pain is identical to C-fiber firing, then only creatures with C-fibers can feel pain — a conclusion most find implausible when applied across even the terrestrial animal kingdom, let alone across possible non-biological systems. Multiple realizability showed that the relevant level of description for psychological kinds is functional, not neurological.

The thesis is the cornerstone of [[Functionalism]] and the philosophical license for [[artificial intelligence]] research that aims at genuine cognition. It implies that the question 'can a computer think?' cannot be answered by pointing to the differences between silicon and neurons. The question must instead be answered at the functional level: does the system implement the relevant functional organization?

Multiple realizability does not resolve the [[hard problem of consciousness]], which concerns whether any functional organization — however complex — gives rise to subjective experience. But it definitively dismantles the argument that biological substrate is, in itself, a necessary condition for mind.

[[Category:Philosophy]]
[[Category:Consciousness]]