From possibility to necessity

Drawing on the YCOE corpus and other occurrences from Old English literature, I demonstrate how to relative infinitives conveying root possibility extended their distributional potential throughout the Old English period to come to denote obligation and, more generally, root necessity. I study the interaction between to relative infinitives — which contribute to determining a head noun — and the modal construction is to (or beon/wesan to), which has played a major role in their evolution. In the course of Old English, this construction undergoes a progressive semantic development that makes it cover a whole range of modal meanings extending from dynamic possibility to deontic necessity (with a probable Latin influence for the latter sense). To account for them, I call on the notion of earmarking (which includes obligation in a broad acceptation). I argue that the extension of its modal meaning is best explained in the light of potentially ambivalent contexts (bridging contexts: Heine 2002), for which several possible interpretations are felt to be equivalent. To relative infinitives are found at the very beginning of Old English and appear to be strongly connected to weak purposive clauses — adjuncts whose specific properties are explored —, thereby accounting for their propensity to convey root possibility. For to relative infinitives, the meaning of necessity emerges as the result of a propinquity (presumably felt by original speakers) with finite relatives that include the construction is to (or beon/wesan to). In other words, such a syntactic analogy (cf. Fischer 2007) provides a missing link to understand the evolution of to relative infinitives from the meaning of root possibility to that of deontic necessity.