Psychological Essentialism and Natural Kinds

According to psychological essentialism, people divide the world into categories that are seen as possessing deep, underlying properties that account for what is common in members of the category. I examine two ways in which this phenomenon has been used either to debunk or to vindicate essentialism about natural kinds. I argue that neither way affects the essentialist thesis, since they depend on other types of evidence that independently reject/support the thesis. I contend that research on psychological essentialism may play a more direct role in a different argument, which addresses the reality of certain natural kinds. To this end, I will revise the issue of the mind-independence of natural kinds through the concept of unification principle. This concept can offer a criterion of natural kindness that allows certain sorts of mental dependence as constitutive of an objective mind-independent kind. I will apply this idea to the case of race, examining some ways in which findings about psychological essentialism could either debunk or vindicate the existence of such a natural kind, and extend it other putative kinds.