Old English *motan, variable force modality, and the presupposition of inevitable actualization
Old English <italic>*motan</italic> and Middle English <italic>*moten</italic> the ancestors of modern <italic>must</italic> are commonly described as ambiguous between a possibility and a necessity reading. I argue instead that in the Alfredian Old English prose, <italic>*motan</italic> was a nonambiguous 'variable force' modal, with the modal force different from both possibility and necessity. I propose that <italic>*motan</italic>'s variable force effect was due to the presupposition of a collapse between possibility and necessity. Informally, <italic>motan</italic><italic>p</italic> presupposed 'if <italic>p</italic> gets a chance to actualize, it will' I then trace the development of <italic>*motan</italic> into a modal genuinely ambiguous between necessity and possibility in Early Middle English.