 Yet another response to unlimited pancomputationalism is implicitly given by Godfrey-Smith (2009). Although Godfrey-Smith is primarily concerned with functionalism rather than computation, his argument is still relevant here. Godfrey-Smith argues that for a mapping to constitute a genuine implementation, the microscopic physical states that are clustered together (to correspond to a given computational state) must be physically similar to one another—there cannot be arbitrary groupings of arbitrarily different physical states, as in the arguments for unlimited pancomputationalism. Godfrey-Smith suggests that his similarity restriction on legitimate mappings may be complemented by the kind of causal and localizational restrictions proposed by Chalmers (1996).