The grammar of knowledge: a cross-linguistic view of evidentials and the expression of information source

[Extract] Every language has a way of speaking about how one knows what one says, and what one thinks about what one knows. In any language, there are ways of phrasing inferences, assumptions, probabilities, and possibilities, and expressing disbelief. These epistemological meanings and their cultural correlates are the subject matter of the present volume. In a number of the world's languages, every sentence must specify the information source on which it is based-whether the speaker saw the event, or heard it, or inferred it based on visual evidence or on common sense, or learnt it from another person. As Frans Boas (1938: 133) put it, 'while for us definiteness, number, and time are obligatory aspects, we find in another language location near the speaker or somewhere else, source of information-whether seen, heard, or inferred-as obligatory aspects.' 'Evidentiality' is grammaticalized marking of information source. This is a bona fide grammatical category, on a par with tense, aspect, mood, modality, directionality, obviation, negation, and person. Just as 'person' can be fused with 'gender' and 'number: evidentiality may be fused with tense or aspect or mood. Its expression, and meanings, may correlate with sentence types: evidentials in questions may have overtones different from evidentials in statements. Exclamatory sentences may have no evidentials at all. Evidentials in commands are very limited in their meanings