 Since T. Stcherbatsky’s two volume study and translation of Dharmakīrti’s Nyāyabindu, entitled Buddhist Logic (i.e., Stcherbatsky 1930/32), one often sees the Buddhist theory of reasons/indices designated as “logic,” a term that sometimes has the unwanted effect of leading readers to think that good reasons for Buddhists are simply those that are formally valid. In fact, the notion of formal validity (i.e., the conclusion’s being guaranteed true, provided the premises are true) is not itself explicitly discussed by Buddhist theoreticians; it is in any case not distinguished from other, more informal, considerations. Instead of formally valid reasons, Buddhist theoreticians developed the notion of a good reason (saddhetu, Tibetan rtags yang dag), i.e., one which satisfies a triple criterion (trairūpya). These three criteria for “goodness” are given in the following fashion from Dharmakīrti on: