 Dignāga had left the problem of the nature of pramāṇas largely open, as he did with the issue of justification. These matters were left to Dharmakīrti, who defines a “source of knowledge” in Pramāṇavārttika II.1 as a “reliable (avisaṃvādin) cognition (jñāna),” by which he means that the cognition is right and reliable as a basis for  action.[29]  Some commentators, such as Dharmottara, have unpacked “reliability” as meaning that the cognition leads to one obtaining (prāpaka) the object one desires, a position which, along with passages concerning arthakriyā, might seem to reinforce the view of some modern scholars that Dharmakīrti was a pragmatist (see e.g., Powers 1994; Cabezon 2000; Katsura 1984).  [30]  Tillemans (1999, 6–12) examines this would-be pragmatism, seeing the theory of truth in Dharmakīrti as a weak form of correspondence. The pragmatism is better taken as a pragmatic theory of justification rather than truth. We can justifiably affirm that a cognition is correct if we can “confirm causal efficacy” (arthakriyāsthiti), by which it is meant that we come to understand that the object does in fact have the causal powers we expected. We can justifiably conclude, for example, that we saw a vase and not some vase-like illusion because after the initial perception we then confirmed that what we saw does really hold water, as we expected and wished (iṣṭa). Note that while most sense perceptions are to be confirmed by subsequent perceptions or inferences, there is no infinite regress here: some perceptions—e.g., those of very familiar objects or of the capacity of such objects to produce effects—need no subsequent confirmation. Logical inference too needs no ulterior confirmation. These are said to be “intrinsically sources of knowledge” (svataḥ prāmāṇya) and are prima facie reliable in that they will be trusted as knowledge unless it is shown that some cause of error is  present.[31]