Page 106 - Encyclopedia of Philosophy of Language

Language and Mind
'Shared knowledge' is one of a number of different terms (such as presupposition, given information, background information, common ground) which have been used to refer to the knowledge, beliefs, and/or discourse entities common to both speaker and addressee. Shared knowledge may be based on general cultural knowledge shared by all members of the same speech community or on more specific experiences shared by speech participants, including information derived from the immediate physical environment and preceding utterances in the discourse. While there is some question as to whether 'shared knowledge' is the most appropriate term for describing the phenomenon at issue here, or indeed whether there is a unitary phenomenon involved here at all, it is clear that assumptions about what is shared by the speaker and addressee in a discourse are involved in both the pro- duction and interpretation of natural language utter- ances. Shared knowledge plays a crucial role in resolving ambiguity, in the appropriate use of specific linguistic constructions, and in defining general con- ditions for successfulcommunication(e.g.,knowledge of the language itself and of appropriateness con- ditions for the performance of various illocutionary
acts such as requesting or promising).
1. What is Shared—Knowledge or Beliefs, Propositions or Entities?
The term 'knowledge' impliesknowledge of some fact. As a condition for successful communication, however, what is crucial is not whether a particular proposition actually is true, but whether it is believed to be true by the participants in a discourse. This suggests that shared knowledge is a pragmatic relation holding between language users and their beliefs about the world. Sperber and Wilson (1995) define an even weaker notion of 'mutual manifestness' which includes not only what speech participants believe, but what they are capable of believing. Others have argued that truth is not a factor here at all, since what is shared is not a proposition, but rather familiarity with some entity (cf. Prince 1981). A number of prob- lems associated with the notion of shared knowledge disappear on this latter view. These include the fact that something can be assumed for the purpose of conversation even though none of the speech par- ticipants believes it to be true, as well as the fact that shared knowledge is not necessarily associated with certain constructions in all contexts (see Gundel 1985).
2. How is Knowledge Shared? The Problem of Infinite Regress
It has been suggested that in order for speaker and hearertoknowwhichassumptionstheyshare,they
must make higher order assumptions about these assumptions. Thus, in order for successful com- munication to take place, it is not only necessary that both speaker and hearer know some proposition (p), but that each knows that the other knows that p and that each knows that the other knows that he/she knows that p, and so on ad infinitum. Shared knowl- edge of this infinitely regressive sort was termed 'mut- ual knowledge' by Schiffer (1972). Since the mutual knowledge requirement is unrealistic from a pro- cessing point of view, Clark and Marshall (1981) pro- pose that such knowledge is not a reality but 'an ideal people strive for because they will want to avoid misunderstanding whenever possible' (p. 27). Speech participants will thus behave as if they have mutual knowledge, even though they cannot conclusively establish its existence. Sperber and Wilson (1995) argue, on the other hand, that 'there is no indication that any particular striving after mutual knowledge goes on' (p. 19) and that 'mutual knowledge is a phil- osopher's construct with no close counterpart in reality' (p. 38). They propose that their own concept of 'mutual manifestness' is not open to the same psychological objections as mutual knowledge, since a claim that an assumption is mutually manifest is not a claim about actual mental states or processes.
3. Degrees of Shared Knowledge: One Phenomenon or Many?
The concept of shared knowledge is crucial in descri- bing appropriateness conditions for a number of con- structions across languages. These include definite reference, focus and topic constructions, cleft sentences, contrastive stress, and pronominal forms. The type or degree of shared knowledge which is required, however, may differ from one construction to another. For example, the demonstrative deter- miner that in That cake wehad wasgood is appropriate only if the referent of the noun phrase which contains it is familiar to both speaker and addressee. On the other hand, appropriate use of a demonstrative pro- noun like that in That wasgood requires not only that the referent be known or familiar, but that it be present in the immediate linguistic or extralinguistic context. And the referent of an unstressed personal pronoun like it in It wasgood requires that the speaker's atten- tion actually be focused on the referent at the current point in the discourse. In order to account for such facts, it is necessary to distinguish different ways in which knowledge can be shared. Much of the current research on shared knowledge is devoted to the ques- tionofhowmanydifferentdegreesofknowledgeneed
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Shared Knowledge J. K. Gundel