On the Dynamics of Conversation

There is a longstanding debate in the literature about static versus dynamic approaches to meaning and conversation. A formal result due to van Benthem (1986, 1996) is often thought to be important for understanding what, conceptually speaking, is at issue in the debate. We introduce the concept of a conversation system, and we use it to clarify the import of van Benthem’s result. We then distinguish two classes of conversation systems, corresponding to two concepts of staticness. The first class, the strongly static conversation systems, corresponds to a generalization of the class of systems that van Benthem’s result concerns. The second class, the weakly static conversation systems, corresponds to a broader class, one permitting a certain commonly recognized form of context sensitivity. In the vein of van Benthem’s result, we supply representation theorems which independently characterize these two varieties of conversation system. We observe that some canonically dynamic semantic systems correspond to weakly static conversation systems. We close by discussing some hazards that arise in trying to bring our formal results to bear on natural language phenomena, and on the debate about whether the compositional semantics for natural language should take a dynamic shape