因明入正理論疏 1.110

1.110

次釋名者，因者所由，釋所立宗義之所由也。或所以義，由此所以所立義成。又建立義，能建立彼所立宗故。或順益義，由立此因順益宗義，令宗義立，是故名因。故《瑜伽》云：「辯因者，謂為成就所立宗義，依所引喻同類異類、現量比量及正教量，建立順益道理言論。」

Second, regarding the explanation of the name, "reason" (hetu) means that from which something arises—it explains that from which the meaning of the established thesis arises. Or it means the rationale—by this rationale, the meaning to be established is accomplished. Moreover, it means to establish—because it can establish that thesis to be established. Or it means to accord and assist—by establishing this reason, it accords with and assists the meaning of the thesis, causing the meaning of the thesis to be established; therefore, it is called the reason. Thus the Yogācārabhūmi states: "Discerning the reason means, in order to accomplish the meaning of the established thesis, relying on adduced examples of similar and dissimilar classes, direct perception, inference, and correct authoritative testimony, one establishes reasoned discourse that accords with and assists it."