As a matter of basic metaphysics, we classify individuals in terms of their relations to other things – for example, a parent is a parent of someone, a larger object is larger than a smaller object. The nature of relativity – the question of how things relate to other things – is a topic that winds its way through the history of philosophy to the present day.

In Ancient Relativity: Plato, Aristotle, Stoics and Skeptics (Oxford University Press, 2020), Matthew Duncombe considers ancient views of relativity from Plato, Aristotle, the Skeptics (particularly Simplicius), and the Stoics (particularly Sextus Empiricus). Duncombe, an assistant professor of philosophy at the University of Nottingham, defends the view that these thinkers shared a common basic position that he calls “constitutive relativity” – the idea that relativity is a matter of the relative being a certain way, rather than having a certain predicate true of it or having a certain feature. He argues that this reading is in the background in a number of arguments in these thinkers, including Parmenides’ main objection to Plato’s Theory of the Forms, and that it comes into its own as a key element of the Skeptics’ opposition to dogmatic belief.