On the Functional Origins of Essentialism

This essay examines the proposal that psychological essentialism re s u l t s f rom a history of natural selection acting on human re p resentation and inference systems. It has been argued that the features that distinguish essentialist re p resentational systems are especially well suited for re p resenting natural kinds. If the evolved function of essentialism is to exploit the rich inductive potential of such kinds, then it must be subserved by cognitive mechanisms that carry out at least three distinct functions: identifying these kinds in the envi ronment, constructing essentialized re p resentations of them, and constraining inductive infer ences about kinds. More o v e r, there are different kinds of kinds, ranging from nonliving sub stances to biological taxa to within-species kinds such as sex, and the causal processes that render these categories coherent for the purposes of inductive generalization vary. If the evolved function of essentialism is to support inductive generalization under ignorance of tru e causes, and if kinds of kinds vary in the implicit assumptions that support valid inductive i n f e rences about them, then we expect different, functionally incompatible modes of essen tialist thinking for different kinds. In part i c u l a r, there should be differences in how biological and nonbiological substances, biological taxa, and biological and social role kinds are essen tialized. The functional differences between these kinds of essentialism are discussed.