People adopt a “cooperative principle” when they communicate, they try to get along with each other by following certain conversational “maxims” that underlie the efficient use of language. Four basic maxims have been proposed after (H.P.Grice,1975 )
*The Maxim of Quality states that speakers' contributions to a conversation ought to be “true”. They should not say what they believe to be false they nor should they say anything for which they lack “adequate evidence”.
*The Maxim of Quantity states that the contribution should be as informative as is required for the purposes of the conversation. One should say neither too little nor too much.
*The Maxim of Relevance states that contributions should clearly relate to the purpose of the exchange.
*The maxim of manner states that the contribution should be perspicuous - in particular, that it should be orderly and brief, avoiding obscurity and ambiguity.
Listeners will normally assume that speakers are following these criteria. Speakers may of course break or flout these maxims- for example, they may lie, be sarcastic, try to be different, or cleaver- but conversation proceeds on the assumption that they are not doing so. Listeners may then draw inferences from what speakers have said (the literal meaning of the utterance) concerning what they have not said(the implications or implicatures of the Utterance).
For example:
A : I need a drink
B; Try the Bell
If “B” is adhering to the cooperative principle, several implicatures arise out of this dialogue.
For example if “the Bell” must be place that sells drinks and is open (as far as B knows); it must be nearby. If “B” is not being cooperative (e.g. if he knows that the Bell is closed, or is the name of a greengrocer's), he is flouting the maxim of quality and relevance.
Deliberate flouting of this kind is uncommon, of course, and only occurs in such special cases as sarcasm, joking, or deliberate unpleasantness. In every day conversation, misunderstandings often take palace as speakers make assumptions about what their listeners know, or need to know, that turn out to be wrong. At such points, the conversation can break down and may need to be repaired, with the participants questioning, clarifying, and crosschecking.
The repairs are quickly made in the following extract, through the use of such pointers as ‘told you' and ‘sorry'.
A: Have you got the time?
B : No, I told you, I lost my watch .
A : Oh, sorry, I forgot .
But it is quite common for participants not to realize that there has been a breakdown, and to continue conversing at cross purposes.