An Indian Theory of Defeasible Reasoning: The Doctrine of upādhi in the Upādhidarpaṇa (Harvard University Press, 2022) is the first translation of this anonymous Navya-Nyāya treatise predating Gaṅgeśa. Eberhard Guhe’s book includes a translation as well as an introduction to the important idea of upādhi, which vitiates inferential reasoning. (Suppose smoke accompanies fire only when the fuel being burnt is wet. This fact would be an upādhi for the inference “There is smoke on the mountain because there is fire on the mountain,” since smoke’s existence doesn’t guarantee fire.) In his quest to define the upādhi as a vitiator of inferential reasoning, the author of the Upādhidarpaṇa takes a controversial position on self-dependence, that the general defining characteristic of an upādhi is property of itself, which Guhe explicates as a non-wellfounded property concept. Beyond the English translation and edition of the Sanskrit text, An Indian Theory of Defeasible Reasoning introduces readers to the basics of Nyāya epistemology and logic, beginning with the idea of inference in early texts and moving through more sophisticated reconstructions by comparison with enumerative induction and set-theoretic approaches to logic.

Malcolm Keating is Associate Professor of Philosophy at Yale-NUS College. His research focuses on Sanskrit works of philosophy in Indian traditions, in the areas of language and epistemology. He is the author of Language, Meaning, and Use in Indian Philosophy (Bloomsbury Press, 2019) and host of the podcast Sutras & Stuff.