Multiple realizability has recently attractedrenewed attention, for example Bickle, 1998;Bechtel and Mundale, 1999; Bechtel and McCauley,1999; Heil, 1999; and Sober, 1999. Many of thesewriters revisit the topic of multiplerealizability in order to show that someversion of a mind-brain identity theory isviable. Although there is much of value inthese recent explorations, they do not addressthe underlying intuitions that have vexedphilosophers of mind since Hilary Putnamintroduced the concern (1967). I argue that thestandard way of construing multiplerealizability is a much stronger claim thanthat (...) of Putnam's intuition alone. I distinguishfour interpretations of the multiplerealizability intuition. Some commonformulations of multiple realizability arealmost certainly true, while others are not atall plausible. I argue that the plausible formsof multiple realizability do not impugn theprospects for a mind-brain Identity Theory. (shrink)