因明入正理論疏 1.16

1.16

第三、明妨難者。一問：「何故不名宗明、喻明，但稱因明？」答：「因有三相，名義寬故。又諸能立皆名為因，非唯一相，宗由此立，總名因明。」

Third, clarifying the objections and difficulties: First question: "Why is it not called 'clarification of the thesis' (pratijñāvidyā) or 'clarification of the example' (dṛṣṭāntavidyā), but solely named hetuvidyā?" Answer: "Because the reason (hetu) has three marks (trairūpya), and its name and meaning are broad. Furthermore, all proof-components (sādhana) are called reasons (hetu), not merely a single mark; since the thesis is established through this, it is collectively named hetuvidyā."