Donkey disjunctions and overlapping updates

This paper is devoted to an analysis of anaphoric dependencies in disjunctive sentences, and consequences for the understanding of the ∃/∀ ambiguity observed with donkey anaphora. The primary focus is on donkey disjunctions, which are sentences where a (negated) existential in an initial disjunct appears to bind a pronoun in a later disjunct, such as "Either there's no bathroom, or its upstairs". The main empirical focus is that donkey disjunctions, like donkey anaphora, exhibit the ∃/∀ ambiguity, and more generally oscillate between homogeneous and heterogeneous readings in a context-sensitive fashion. The paper then proceeds in two steps: first, a principled analysis of donkey disjunctions is developed in the context of a Bilateral Update Semantics (BUS). BUS, by default, generates heterogeneous readings for donkey anaphora/donkey disjunctions (i.e., ∃ readings, in a positive context). In order to account of homogeneous readings, the conjecture is that sentences may be interpreted exhaustively relative to their negations. This has non-trivial consequences due to the non-classicality of BUS — specifically, a failure of the Law of Non-Contradiction.