ABSTRACT
This chapter examines Thomas S. Kuhn's idea that scientific revolutions are characterized by change in the taxonomic structure which scientific theories impose upon the world. It considers Kuhn's claim that change of structure gives rise, at the semantic level, to localized translation failure between interdefined subsets of terms. The chapter analyses untranslatability to a relation of non-overlap which Kuhn claims to hold between natural kinds. It explores Kuhn's claim that incommensurability entails the falsity of the realist idea of progress as increase of truth about a fixed set of entities. The chapter describes Kuhn's rejection of the correspondence theory of truth. It suggests that the scientific realist need find little to object to in the thesis of taxonomic incommensurability. The taxonomic incommensurability thesis is in several respects superior to earlier versions. The semantic variance associated with taxonomic change lies at the heart of incommensurability.
