Conversational Maxims and Implicatures are the foundation of the philosopher H.P. Grice's pragmatic account of communication. To account for the distinction between what is directly said and what is conveyed by an utterance, Grice proposed that in conversing, participants proceed according to an implicit assumption that he terms the cooperative priniciple:
"Make your conversational contribution such as is required, at the stage at which it occurs, by the accepted purpose or direction of the talk exchange in which you are engaged."
Another set of assumptions, called conversational maxims, underlie the cooperative priniple:
1. Quality: Try to make your contribution one that is true. (1) Do not say what you believe to be false. (2) Do not say that for which you lack adequate evidence. 2. Quantity (1) Make your contribution as informative as is required for the current purposes of the exchange. (2) Do not make your contribution more informative than is required. 3. Relation: Be relevant. 4. Manner: Be perspicuous. (1) Avoid obscurity of expression. (2) Avoid ambiguity. (3) Be brief (avoid unnecessary prolixity). (4) Be orderly.
Grice demonstrates that conversational participants convey meanings beyond that which is said if they assume that the other is adhering to the cooperative principle and its maxims. Conversationalists can deal with the maxims in several ways: They can follow them, violate one of them, opt out of one of them, sacrifice one to the other if they clash, or flout them. Lying, for example, violates the maxim of quality. The maxims derive their explanatory power from what happens when behavior appears not to conform to them. Thus, as Green (1989) explains, since speakers assume that hearers adopt the cooperative principle and its maxims for interpreting speech behavior, the speaker is free to exploit it, and to speak in such a way that his behavior must be interpreted according to it. If the speaker's remark seems irrelevant, the hearer will attempt to construct a sequence of inferences that make it relevant or at least cooperative. This exploitation of the maxims is the basic mechanism by which utterances are used to convey more than they literally denote, and Grice called it implicature.
Acts of language that run counter to Grice's Conversational Maxims are termed violations. But if we find a culture in which violations rather than the maxims are the norm, the theory loses much of its explanatory power. The violations may in fact not be violations at all, and acts in accordance with the maxims may actually become violations. Perhpas it is not a theory at all, but a normative model -- an unintended prescription for using language.