ABSTRACT
Natural kind essentialism (NKE) is a specification of the intuitive idea that there are some mind-independent or objective categories in nature. These categories are thought to be characterized by a shared essence, which may involve intrinsic or extrinsic properties, mechanisms, or causal history. While the ontological basis of natural kinds has its roots in antiquity and especially Aristotle, the contemporary notion of a “natural kind” in philosophical discussion is often traced to William Whewell's and John Stuart Mill's work in the 1800s. In its more modern form, NKE was popularized in the 1970s mainly by Saul Kripke and Hilary Putnam. Traditionally, NKE has been associated with intrinsic and microstructural properties, but contemporary work has made it clear that more refined versions of NKE may have to accept extrinsic or relational essences.
