Assessing the inferential strength of epistemic must

This article presents four experiments that investigate the meaning of English and Italian statements containing the epistemic necessity auxiliary verb must/dovere, a topic of long-standing debate in the philosophical and linguistics literature. Our findings show that the endorsement of such statements in a given scenario depends on the participants’ subjective assessment about whether they are convinced that the conclusion suggested by the scenario is true, independently from their objective assessment of the conclusion’s likelihood. We interpret these findings as suggesting that English and Italian speakers use epistemic necessity verbs to communicate neither conclusions judged to be necessary (contrary to the prediction of the standard modal logical view) nor conclusions judged to be highly probable (contrary to the prediction of recent analyses using probabilistic models) but conclusions whose truth they believe in (as predicted by the analysis of epistemic must as an inferential evidential). We suggest that this evidential meaning of epistemic must/dovere might have arisen in everyday conversation from a reiterated hyperbolic use of the words with their original meaning as epistemic necessity verbs.