Now let’s have a look at language in use. To understand language use we need to look at the propositions a sentence produces, that is, what is talked about in an utterance and the illocutionary acts performed through the expression of those propositions, which involve doing and not just saying something. For example people promise, warn or invite. Propositions and illocutionary acts do not occur in isolation but combine to form what is termed discourse (stretches of language perceived to be meaningful, unified and purposive). The propositions expressed are linked to what has gone before by means of linguistic clues which act as markers to guide us through the discourse, i.e. “cohesion”. The illocutionary acts performed by the propositions also fit together, that is, they are “coherent”.
Communication depends on co-operation to function smoothly and this entails making certain assumptions. I assume a speaker/writer intends what s/he says to be informative and relevant. Moreover meaning is not always explicitly stated but has to be inferred. We also learn that different linguistic elements occur with certain frequency, and that discourse has common patterns. All this knowledge constitutes “common sense” conventions or a set of basic rules. People find out about these conventions through their experience of language use.