因明入正理論疏 1.29

1.29

二者能破，敵申過量，善斥其非，或妙徵宗，故名能破。（此有二義：一顯他過，他立不成；二立量非他，他宗不立。諸論唯彰顯他過破，理亦兼有立量徵詰。發言申義，證敵俱明，敗彼由言，故名能破也。）

Second is valid refutation (dūṣaṇa): when the opponent presents a faulty argument, skilfully rebuking his errors, or marvelously cross-examining his thesis, is therefore called valid refutation. (This has two aspects: first, exposing the other's faults so that the other's proof is unestablished; second, establishing an argument to negate the other so that the other's thesis cannot stand. The various treatises only indicate the refutation that exposes the other's faults, but in principle it also includes establishing an argument to interrogate. Uttering words to expound the meaning, both the witness and the opponent are clarified; defeating the other is through words, hence it is called valid refutation.)