Toward a unified semantics for English "either"

This paper proposes that the additive and disjunctive uses of English either share a semantic core. Formulated in Inquisitive Semantics, this core involves a requirement that either apply to an inquisitive proposition, which accounts for either’s co-occurrence with disjunction. It also includes an additive presupposition that is more flexible than has previously been assumed in the literature, which allows the analysis to account for novel data in which additive either conveys that a proposition is unexpected or undesirable. The inability of either to appear in alternative questions is also pointed out and accounted for.