ABSTRACT
This chapter reviews what it means to think of a category as a natural kind, how natural kind terms get their status in psychology and language, and how the language of natural kinds shapes cognition, development, and behavior. The prototypical example of a category that people think of as a natural kind is a basic level species. People also think that natural kinds have absolute boundaries: Although natural kind categories have a graded structure, and some category members are viewed as more representative and generalizable than others, even an unusual bird is still fully a bird, while an unusual piece of furniture can be “sort of” a chair. Once people come to think of a particular category as a natural kind, these beliefs have a range of consequences for how they use that category in their daily lives.
