On the distinction between ambiguity and vagueness in grammatical change

Abstract We argue that we should maintain the distinction between ambiguity and vagueness in grammatical change, especially in usage-based linguistics, as it offers a more fine-grained perspective on types of context, change, and linguistic structure. Drawing on previous research, we present two case studies: the semantic history of be going to , and the morphosyntactic history of Mandarin modals and conditionals. These studies show that the initial relation involved in grammatical change is one of vagueness. We also contrast our usage-based perspective with that of frameworks where the clause is hierarchically organised such that the initial relation is more likely one of ambiguity.