Editing History of logic (section)

=== Dignaga ===
However, [[Dignāga]] (c 480–540 AD) is sometimes said to have developed a formal syllogism,<ref>Bochenski pp. 431–437</ref> and it was through him and his successor, [[Dharmakirti]], that [[Buddhist logic]] reached its height; it is contested whether their analysis actually constitutes a formal syllogistic system. In particular, their analysis centered on the definition of an inference-warranting relation, "[[vyapti]]", also known as invariable concomitance or pervasion.<ref name="Matilal">{{cite book |author-last=Matilal |author-first=Bimal Krishna |title=The Character of Logic in India |date=1998 |publisher=State University of New York Press |location=Albany, New York, USA |isbn=9780791437407 |pages=12, 18}}</ref> To this end, a doctrine known as "apoha" or differentiation was developed.<ref>Bochenksi p. 441</ref> This involved what might be called inclusion and exclusion of defining properties.

Dignāga's famous "wheel of reason" (''[[Hetucakra]]'') is a method of indicating when one thing (such as smoke) can be taken as an invariable sign of another thing (like fire), but the inference is often inductive and based on past observation. Matilal remarks that Dignāga's analysis is much like John Stuart Mill's Joint Method of Agreement and Difference, which is inductive.<ref>Matilal, 17</ref>