What is Common Ground?

Abstract

Language is primarily a form of social interactive behaviour in which a speaker, writer or signer (henceforth S) addresses utterances (U) to an audience (H). It requires S to make certain assumptions about H’s ability to understand U. This includes choice of topic, language, language variety, style of presentation, and level of presentation (because, for instance, addressing a neophyte or a child must be differently handled from addressing a group of experts). These assumptions constitute what can conveniently be called “common ground”. They have been subsumed to context (e.g. Allan 1986; Duranti 1997); and at least a part of the common ground constitutes what Lewis (1969) referred to as “common knowledge”, a term adopted by Stalnaker (1973). Schiffer (1972) called it “mutual knowledge*”. Prince (1981) rejected “shared knowledge”, preferring “assumed familiarity”. Following Grice (1981, 1989), Stalnaker (2002) named it “common ground”, which he described as “presumed background information shared by participants in a conversation” [...] “what speakers [take] for granted—what they [presuppose] when they [use] certain sentences”. A fatal flaw was carried over from Schiffer’s definition of mutual knowledge* into Stalnaker’s definition of common ground: “It is common ground that φ in a group if all members accept (for the purpose of the conversation) that φ, and all believe that all accept that φ, and all believe that all believe that all accept that φ, etc.” (Stalnaker 2002: 716). The recursion within this definition would necessitate infinite processing on the part of each of S and H. This flaw has been accepted and repeated by many since (e.g. Kecskes and Zhang (2009, 2014)). Clark (1996) attempted to circumvent it but his definition includes a clause that calls itself, thus creating an endless loop. In this essay I suggest a way, inspired by Lee (2001), to characterize common ground from the points of view of both S and H and which does not admit runaway recursion. In line with Stalnaker’s mingling of presupposition and common ground, it refers to the preconditions on illocutions.