Plato’s invention of the metaphor of carving the world by the joints gives him a privileged place in the history of natural kind theory in philosophy and science; he is often understood to present a paradigmatic but antiquated view of natural kinds as possessing eternal, immutable, necessary essences. Yet, I highlight that, as a point of distinction from contemporary views about natural kinds, Plato subscribes to an intelligent-design, teleological framework, in which the natural world is the product of craft and, (...) as a result, is structured such that it is good for it to be that way. In Plato’s Philebus, the character Socrates introduces a method of inquiry whose articulation of natural kinds enables it to confer expert knowledge, such as literacy. My paper contributes to an understanding of Plato’s view of natural kinds by interpreting this method in light of Plato’s teleological conception of nature. I argue that a human inquirer who uses the method identifies kinds with relational essences within a system causally related to the production of some unique craft-object, such as writing. As a result, I recast Plato’s place in the history of philosophy, including Plato’s view of the relation between the kinds according to the natural and social sciences. Whereas some are inclined to separate natural from social kinds, Plato holds the unique view that all naturalness is a social feature of kinds reflecting the role of intelligent agency. (shrink)

In Archytas of Tarentum, Carl Huffman reconstructs Archytas’ theory of definition by linking definitions to the mathematical study of ratios and proportions. This paper considers whether and how Archytas used definitions and whether he possessed a theory of definition. Our evidence does not support the claim that Archytas has a theory of definition, and his approach to the science of harmonics suggests that he relied on analogies and proportions in the practice of inquiry. We understand sounds and other entities by (...) placing them in a network of relations governed by mathematical proportions. Although he does not seem to have formulated definitions of sound, Archytas pursued inquiry into motion and rest by formulating definitions in such a way that they fit into a larger network of causal explanations. (shrink)