At-issue proposals and appositive impositions in discourse

Potts (2005) and many subsequent works have argued that the semantic content of appositive (non-restrictive) relative clauses, e.g., the underlined material in John, who nearly killed a woman with his car, visited her in the hospital, must be in some way separate from the content of the rest of the sentence, i.e., from at-issue content. At the same time, there is mounting evidence from various anaphoric processes that the two kinds of content must be integrated into a single, incrementally evolving semantic representation. The challenge is how to reconcile this informational separation with these pervasive anaphoric connections. We propose a dynamic semantic account that accomplishes this by taking appositive and at-issue content to involve two different kinds of updates to the Context Set (CS). Treating the context set as a distinguished propositional variable, p^cs, we argue that appositives directly impose their content on the CS by eliminating possible values assigned to p^cs. In contrast, we treat at-issue assertions as introducing a new propositional dref and proposing that p^cs be updated with its content, subject to addressee's response. In addition to capturing the behavior of appositives in discourse, we show that the account can be extended to capture the projection of appositive content past various sentential operators.