AAP 2026 CONFERENCE

Some proponents of multiple realization attempt to eat their realized cake while having their reduction, too. The constrained identity account of multiple realization offered by Polger and Shapiro (2016) is such an attempt, and in this paper I argue that it, and attempts like it, will lead to a complex dilemma for proponents of hybrid identity/realization accounts. Either they adhere to Kim’s (1992) principle of the causal individuation of kinds, in which case they must deal with Kim’s own reductionist dilemma for multiple realization, or they follow Polger and Shapiro (2016) in weakening Kim’s principle to the causally-relevant individuation of kinds. However, this leads to a relativisation of kinds to human interests, and thus to a pragmatist approach to science. Since multiple realizationists tend to be realists (after all, they think one set of entities at a basic level of reality makes another set of entities real), this is a problem for them. After diagnosing the problem they face, I offer them only unpalatable solutions: accept one or other fork of the dilemma and agree with Kim’s extreme reductivism or accept a pragmatism which admits only a watery realism.