Direct evidentiality in the grammar of English: must have in a London dialect

The modal auxiliary form must plus perfect aspect (must have +V-en) has recently acquired the meaning of direct evidentiality in Multicultural London English, the new London dialect. Because the new meaning is a recent innovation we have a rare opportunity to witness its development at first hand, unlike earlier changes in the history of must. Our analysis supports the view that the classic definition of evidentiality in terms of information source is too narrow to explain the expression of evidentiality in spoken interaction, and that a broader definition in terms of epistemic authority is more appropriate. We argue that the direct evidential meaning is a coherent further step in the semantic changes undergone by must during its history. It represents a previously undocumented pathway in the grammaticalisation of evidentiality. It also supports the view that evidentiality is not a purely lexical phenomenon in English.