The secret history of 'must'
Igor Yanovich, MIT

Abstract
Dictionaries of Old English describe the primary meaning of the modal *motan (>modern must) as that of possibility and permission. It is only by the end of the 15th cent. that the modal completely turned into a normal necessity modal it is today. In the talk, I propose a new semantics for Early Old English *motan, arguing that it was a variable-force modal somewhat resembling modals recently discovered in several languages of the Pacific Northwest (Rullmann et al. 2008, Peterson 2010, Deal 2011). I trace the development of *motan throughout Late Old English and Early Middle English, showing how it turned from an unambiguous variable-force modal into a modal ambiguous between several pure-necessity and not-quite-necessity meanings.