 Some contemporary nonreductive physicalists deny that mental kinds are correctly identified with functional kinds. A popular criticism of this sort hinges on issues about individualism in psychology. But Putnam later used multiple realizability itself to argue against functionalism, arguing that mental kinds are both “compositionally” and “computationally” plastic. The first point is his familiar contention of the multiple realizability of the mental on the physical. The second contends that the same mental kind can be a property of systems that are not in the same computational state (see Putnam 1988 for details). In this argument, multiple realizability strikes back against the very theory of mind it initially was used to defend. 