Taranto’s Dissertation on Discourse Adjectives

Gina C Taranto. “Discourse Adjectives”:http://ling.ucsd.edu/~taranto/DiscourseAdjectives2up.pdf. PhD Dissertation, UCSD. 2003.

bq. This thesis introduces Discourse Adjectives (DAs), a natural class whose members include apparent, evident, clear, and obvious, as in (1).
(1) a. It is clear that Briscoe is a detective.    b. It is clear to you and me that Briscoe is a detective.
Of primary concern are the semantics of DAs in sentences like (1a), in which the conceptually necessary experiencer of clear is not expressed syntactically, and is interpreted much like (1b), with the relevant experiencers of clarity interpreted as the discourse participants - that is, both the speaker and the addressee.
I argue that the meaning of utterances such as (1a) are highly unusual semantically, in that they operate entirely on a metalinguistic level. Interlocutors use such utterances to provide information about their conversation rather than their world. Sentence (1a) does not provide new information about Briscoe, rather, it provides information about the interlocutor’s beliefs about the designated proposition, in terms of the current conversation.
My analysis begins with a Stalnakerian model of context-update, as formalized by Heim (1982, 1983) and Beaver (2000). I augment this model with Gunlogson’s (2001) representation of individual commitment sets of speaker and addressee within the Common Ground of a discourse, and Barker’s (2002) compositional theory of vagueness.
My proposal relies on the (vague) degree of probability that the Discourse Participants assign to the truth of a proposition; the context-update effect of an utterance of (1a) removes from consideration those possible worlds in which the discourse participants do not believe the proposition expressed by Briscoe is a detective satisfies a vague minimum standard for ‘clarity’. The semantics of utterances with DAs are shown to depend directly on probability, and only indirectly on truth. I argue that after an utterance with a DA is accepted into the Common Ground, interlocutors are licensed to proceed as if the designated proposition is true, if only for the current discussion.
DAs are argued to have the ability to publicly commit all discourse participants to the content of their complements. This is shown to have a synchronization effect on the Common Ground of a discourse, which explains how it can be useful to have an expression type that has no normal descriptive content.