Apoha

Apoha (Sanskrit: अपोह) is a Buddhist epistemological theory first proposed by the philosopher Dignāga (c. 480 – c. 540 CE) in his seminal text Pramāṇasamuccaya. The theory went on to be significantly elaborated upon and extended by Dignāga's successor Dharmakīrti (6th or 7th century CE). Buddhist philosophers of the logico-epistemological school, of which Dignāga and Dharmakīrti were the most influential, were nominalists, i.e., they held the position that the world is composed of unique particulars and that the concepts in terms of which we think and communicate have no counterpart in reality but are mere mental impositions. Our categories of thought and language are thus, according to the Buddhists, purely subjective – the result of our past karmic impressions that obscure from us the true nature of reality.

Apoha theory was proposed to provide an explanation for how, in the absence of objectively existent universals, we are able to form concepts and effectively use them to communicate and achieve practical ends. Dignāga defined apoha as a theory of classification based on exclusion. He said that a category such as 'cow' is arrived at not by the inclusion of all objects we would, based on some criteria, identify as cows, but by the exclusion of all objects we would identify as 'non-cows.' Concepts thus involve a double negation - the category of 'cow' is, in fact, the category of all 'not non-cows.' Since a negation or an absence cannot, according to the Buddhists, be objectively real (since absences are not caused and have no causal efficacy), this shows that concepts, though referring to a class of particulars, have no basis in reality.