Evidentiality as a grammaticalization passenger

This article investigates the grammaticalization patterns of evidentiality from a cross-linguistic perspective with a focus on Lhasa Tibetan. It documents the history of the evidential morphemes ’dug, -song, -bzhag, and =ze from Old Literary Tibetan to modern spoken Lhasa Tibetan. Our analyses show that these morphemes started grammaticalizing before encoding evidentiality. We argue that, through pragmatic strengthening, evidentiality tends to infiltrate forms which have already grammaticalized to express other semantic domains. These patterns of grammaticalization are confirmed by diachronic and reconstructed data from genetically unrelated languages. Evidentiality thus tends to be a ‘grammaticalization passenger’ (i.e., a conventionalized meaning which used to be merely implied from the recurrent contexts of a grammaticalized form) rather than a ‘grammaticalization target’ (i.e., a functional domain which triggers grammaticalization). This may explain why evidentiality is less often grammaticalized than other notions, such as time or modality, in the world’s languages.