Parenthesis and presupposition in discourse

Parentheses do not affect the semantic truth conditions of the host clause, but they do affect the discourse structure. We propose a maximally simple update system for the conversational context. Presuppositions are treated as past requests for the interlocutor’s consent. Parentheticals act like overt presuppositions unless they are linearly last in the utterance, in which case they can be taken as a current update request. This has consequences for the interlocutor’s ability to target a parenthetical message. We predict that sentence-final parentheses, and in particular attributive appositives, can be generically addressed, but medial ones only by a specific response. We also discuss why certain non-clausal parentheses, including identifying appositions, behave differently.