No doubt and related expressions

The epistemic adverb no doubt refers literally to absence of doubt, and hence to complete certainty, but it is actually described in the literature as expressing less than full certitude and as more or less synonymous with ‘very probably’. This contribution uses corpus data to examine the meaning and pragmatic uses of no doubt and of the formally and semantically closely related expressions there is no doubt and I have no doubt in present-day English. An explanation for how certainty adverbs such as no doubt have actually come to express some doubt or uncertainty is sought by considering data from historical corpora. It is argued that grammaticalization is a factor in this meaning development. But from a theoretical point of view the relationship between ‘certainty’ and ‘uncertainty’ needs an explanation which goes beyond the description of individual lexical items. This contribution shows that the explanation for such a relationship must be sought in the rhetorical exploitation of epistemic expressions.