in presupposition denials.

This paper explores a puzzling polarity-based asymmetry in the use of in sentences that deny presuppositions. It argues that this asymmetry is produced by the interaction of 's controversial additive presupposition with the alternatives that are salient in the relevant contexts and demonstrates that this proposal makes good crosslinguistic predictions. Along the way, this paper shows that presupposition denials are a fruitful testing ground for uncovering details about the behaviour of and the role of presuppositions triggered within focus alternatives.