Abstract

This chapter deals with the main characteristics of natural kinds, and analyzes three approaches to them. The first approach argues that natural kinds are characterized by their essential properties (in a modern, scientific sense), but encounter difficulties even on the physico-chemical level, which is where it seems to be better implemented. On the other hand, the constructivist stance, much more liberal, does not explain why certain kinds are inductively useful and not others. Third, an introduction, with comments, is provided on the approach of Richard Boyd, among others, which understands natural kinds as homeostatic property clusters that accommodate to the causal structure of the world. In this view, natural kinds are usually fuzzy sets with no clear boundaries, subject to time and space limitations, and relative to some perspective. However, it solves the problems of the other approaches mentioned without forgoing a realistic conception of natural kinds. Finally, a proposal is made on how an application of Boyd’s ideas to the analysis of laws of nature can help to solve the old chestnut about the distinction between scientific laws and accidentally true generalizations.