Everyday patterns of speech (vyavahāra) are taken as a starting point for theorizing in epistemology as in other areas of philosophy. So, for example, perception and inference—more exotic candidate sources, too—are defended as veritable knowledge-generators by the observation that people commonly regard them in that way. People cite a belief’s pedigree in questions of justification. Note that even in English we do commonly recognize perception and some of the others as certificational. Thus this seems to be a common human practice, not restricted to classical Indian civilization, for sometimes we say, for instance, “S is indeed over there, since I see him,” and “You couldn’t really have perceived S because condition Y does not hold” (“You can’t see anyone from this distance”). Habits of speech are reinforced by success in action, classical theorists recognize in accepting the presumptive authority of common opinion. But “a knowledge source” may be thought of as a technical term, one that entails factivity, as we have seen, as a matter of definition. Similarly with justification (prāmāṇya), the having of which, if veritable (or objective), as opposed to the apparent (ābhāsa), means that the justified cognition is true.