The role of ambiguity and vagueness in language change

In linguistic research, the concepts of ambiguity and vagueness are often confused and frequently invoked to describe synchronic facts and explain diachronic processes. This article illustrates the differences and similarities between the two phenomena, defines their position within the domain of semantic indeterminacy, and discusses their role in linguistic change. The examples show that while ambiguity is intertwined with various mechanisms of change, acting as both a source and a product of innovation, vagueness plays a marginal role, being mainly a side effect of ongoing change or a tool of communicative strategies of vague language. Moreover, intentional vagueness can only promote speaker-driven innovations, whereas ambiguity can trigger hearer-driven changes that unfold broader diachronic scenarios.