 Much literature concerned with speech acts is curiously disconnected from research in the semantics of natural language emphasizing pragmatic factors. For instance, Stalnaker (1972, 1973, 1974), Lewis (1979, 1980), Thomason (1990) and others have developed models of the kinematics of conversations aimed at understanding the role of quantification, presupposition (both semantic and pragmatic), anaphora, deixis, and vagueness in discourse. Such models typically construe conversations as involving an ever-developing set of Propositions that can be presupposed by interlocutors. This set of Propositions is the conversational common ground, defined as that set of Propositions that all interlocutors take to be true, while also taking it that all other interlocutors take them to be true. If a Proposition p is in a conversation’s common ground, then a speaker may felicitously presuppose p’s truth. Suppose then that the Proposition that Singapore has a unique King is in a conversation’s common ground at given point; then a speaker may felicitously utter a sentence such as ‘The present King of Singapore is wise,’ or ‘Singapore’s king is sleeping’. Other parameters characterizing a conversation at a given point include the domain of discourse, a set of salient perceptible objects, standards of precision, time, world or situation, speaker, and addressee. The set of all values for these items at a given conversational moment is often referred to as “conversational score”.