Dignaga c. 480 AD – c. 540 AD

Dignaga was an Indian Buddhist logician and epistemologist and the founder of the Buddhist tradition of logic and philosophy of knowledge. His Pramana-samuccaya, the Compendium of Valid Cognition, established the framework in which Buddhist epistemology would be debated for the next thousand years, including the doctrine that there are exactly two valid means of knowledge, perception and inference, with distinct objects. He developed a sophisticated theory of inference and an original semantic doctrine of apoha, according to which words pick out their objects by the exclusion of what they are not.