At any stage of verbal interaction both S [Speaker] and A [Addressee] possess a huge amount of pragmatic information, PS and PA, respectively. In saying something to A, S’s intention is to effect some kind of modification in PA. In order to achieve this, S must form some kind of communicative intention, a kind of mental plan concerning the particular modification that he wishes to bring about in PA. S’s problem is to formulate his intention in such a way that he has a reasonable change of leading A to the desired modification of his pragmatic information. S will therefore try to anticipate the interpretation that A is likely to assign to his linguistic expression, given the current state of PA. This anticipation on the part of S thus requires that S should have a reasonable picture of the relevant parts of PA. […] A, on the other hand, interprets S’s linguistic expression in the light of PA and of his estimate of PS, and thus tries to arrive at a reconstruction of S’s presumed communicative intention. The interpretation arrived at may lead A to bring about that modification in PA which corresponds to S’s communicative intention. If A does not arrive at an interpretation which has a reasonable match with S’s communicative intention, there will be a misunderstanding between S and A.
- Dik (1989), a pag.8

Verbal interaction, i.e., social interaction by means of language, is a form of structured cooperative activity. It is ‘structured’ (rather than random) activity in the sense that it is governed by rules, norms, and conventions. It is ‘cooperative’ activity in the obvious sense that it needs at least two participants to achieve its goals.
- Dik (1989), a pag.3