Swampman is the subject of a philosophical thought experiment introduced by Donald Davidson, in his 1987 paper “Knowing One’s Own Mind”. The experiment runs as follows:
Suppose Davidson goes hiking in the swamp and is struck and killed by a lightning bolt. At the same time, nearby in the swamp another lightning bolt spontaneously rearranges a bunch of molecules such that, entirely by coincidence, they take on exactly the same form that Davidson’s body had at the moment of his untimely death.
This being, whom Davidson terms ‘Swampman’, has, of course, a brain which is structurally identical to that which Davidson had, and will thus, presumably, behave exactly as Davidson would have. He will walk out of the swamp, return to Davidson’s office, and write the same essays he would have written. He will interact like an amicable person with all of Davidson’s friends and family, and so forth.
Davidson holds that there would nevertheless be a difference, though no one would notice it. Swampman will appear to recognize Davidson’s friends, but it is impossible for him to actually recognize them, as he has never seen them before. As Davidson puts it, “it can’t recognize anything, because it never cognized anything in the first place.”