Stance and modals of obligation and necessity in academic writing

Abstract Variation has been demonstrated in modal use between written and spoken registers and between disciplines. This article investigates variation within a discipline by comparing modals of obligation and necessity used in three science genres. Obligation modals project strong authoritative stance, thus contrasting with the tendency in academic writing towards tentativeness. The modal auxiliaries must and should and quasi-modals have to and need to are investigated using student writing from the BAWE (British Academic Written English) corpus and a corpus of published research articles. Findings include a dearth of obligation modals in the empirical genres (research articles and laboratory reports). Also a greater prominence was found of dynamic modal meaning (where necessity arises from circumstances) rather than deontic meaning (where the necessity arises from human authority or rules). A further finding is the prominence of objective meaning in the science register compared with the International Corpus of English (Collins 2009a).