As already explained, Vaise~ika is primarily concerned with the essential knowledge of the six (or seven in the later tradition of Vaise~ika) categories. Hence a discussion on the nature and types of knowledge! is entirely relevant to the system of Vaise~ika.Kal).ada has expounded that basically there are two types of knowledge: non-veridical (avidya)2 and veridical (vidya).3 It should be clarified here that the term 'avidya' does not denote ignorance (ajfiana) as held in the Vedantic view. In Vaise~ika it simply suggests that type of knowing condition wherein the object could not be known properly:

Kal).ada now sets himself to dealing with what he takes to be the main question regarding knowledge, after the digression he has allowed himself for explicating the conception of the self and the mind. He refers (VS, 8/1/1) the reader explicitly to the definition of knowledge (jfianam vyakhyatam) given while dealing with the substances (drave~u) (sic.) (VS, 3/1/18). He makes it clear that he takes knowledge to initiate with the self by merely observing now, that the self and the mind (atma manansi) are not evident to perception (a-pratyakshe) as the sense-organs obviously are. But this fact does not come in the way of our mapping out the field of knowledge, since what counts for the purpose, is the operative rule (vidhih) in terms of which knowledge results. Kal).ada takes the main problem here to be, to mark the grounds of certainty in respect of the various types of knowledge. And for Kal).ada the types of knowledge are determined by the categories.