"Ascertainment" (_nirṇaya_, i. 40) is right knowledge or a perception of the real state of the case. It is of four kinds as produced by perception, inference, analogy, or testimony. "Discussion" (_váda_) is a particular kind of conversation, having as its end the ascertainment of truth (i. 41). "Wrangling" (_jalpa_) is the talk of a man only wishing for victory, who is ready to employ arguments for either side of the question (i. 42). "Cavilling" (_vitaṇdá_) is the talk of a man who does not attempt to establish his own side of the question (i. 43). "Dialogue" (_kathá_) is the taking of two opposite sides by two disputants. A "fallacy" is an inconclusive reason which is supposed to prove something, and this may be of five kinds, the "erratic," the "contradictory," the "uncertain," the "unproved," and the "precluded" or "mistimed" (Sút. i. 44-49). "Unfairness" (_chhala_) is the bringing forward a contrary argument by using a term wilfully in an ambiguous sense; this is of three kinds, as there may be fraud in respect of a term, the meaning, or a metaphorical phrase (i. 50-54). "Futility" (_játi_) is a self-destructive argument (i. 58). This is of twenty-four kinds (as described in the fifth book of the Nyáya aphorisms) (1-38). "Occasion for rebuke" is where the disputant loses his cause [by stupidity], and this is of twenty-two kinds (as described in the fifth book of the aphorisms, 44-67). We do not insert here all the minute subdivisions through fear of being too prolix,--they are fully explained in the aphorisms. But here an objector may say, "If these sixteen topics, proof, &c., are all thus fully discussed, how is it that it has received the name of the Nyáya Śástra, [as reasoning, _i.e._, _Nyáya_, or logic, properly forms only a small part of the topics which it treats of?]" We allow the force of the objection; still as names are proverbially said to be given for some special reason, we maintain that the name Nyáya was rightly applied to Gotama's system, since "reasoning," or inference for the sake of another, is justly held to be a predominant feature from its usefulness in all kinds of knowledge, and from its being a necessary means for every kind of pursuit. So it has been said by Sarvajña, "This is the pre-eminent science of Nyáya from its establishing our doctrines against opponents, and from its producing action;"[212] and by Pakshila Swámin, "This is the science of reasoning (_ánvíkshikí_) divided into the different categories, 'proof,' &c.; the lamp of all sciences, the means for aiding all actions, the ultimate appeal of all religious duties, well proved in the declarations of science."[213]