Concept
A philosophical zombie (or "p-zombie") is a being in a thought experiment in philosophy of mind that is physically identical to a normal person but does not have conscious experience. For example, if a philosophical zombie were poked with a sharp object, it would not feel any pain, but it would behave exactly the way any conscious human would. Philosophical zombie arguments are used against forms of physicalism and in defense of the "hard problem of consciousness", which is the problem of accounting in physical terms for subjective, intrinsic, first-person, what-it's-like-ness experiences. Proponents of philosophical zombie arguments, such as the philosopher David Chalmers, argue that since a philosophical zombie is by definition physically identical to a conscious person, even its logical possibility refutes physicalism, because it establishes the existence of conscious experience as a further fact. Philosopher Daniel Stoljar points out that zombies need not be utterly without subjective states, that even a subtle psychological difference between two physically identical people, such as in the taste of coffee, is enough to refute physicalism. Such arguments have been criticized by many philosophers. Some physicalists, such as Daniel Dennett, argue that philosophical zombies are logically incoherent and thus impossible, or that all humans are philosophical zombies; others, such as Christopher Hill, argue that philosophical zombies are coherent but metaphysically impossible. Philosophical zombies are associated with David Chalmers, but it was philosopher Robert Kirk who first used the term "zombie" in this context in 1974. Before that, Keith Campbell made a similar argument in his 1970 book Body and Mind, using the term "Imitation Man." Chalmers further developed and popularized the idea in his work. There has been a lively debate about what the zombie argument shows. Critics who primarily argue that zombies are not conceivable include Daniel Dennett, Nigel J. T.