Conversational Contrast and Conventional Parallel: Topic Implicatures and Additive Presuppositions

Additive particles or adverbs like too or again are sometimes obligatory. This does not follow from the meaning commonly ascribed to them. I argue that the text without the additive is incoherent because the context contradicts a contrast implicature stemming from the additive's associate, and that the text with the additive is coherent because the presupposed alternative is added to the associate, so that the implicature does not concern that alternative. I show that this analysis is better than the account offered by Krifka (1999, Proceedings of SALT 8) and that, contra Zeevat (2003, Optimality Theory and Pragmatics, 91–111), the notion of a presupposition is essential.