In language, pragmatics and discourse are closely connected. Discourse is the method, either written or verbal, by which an idea is communicated in an orderly, understandable fashion. Used as a verb, discourse refers to the exchange of ideas or information through conversation. Comparatively, pragmatics involve the use of language to meet specific needs or for a predetermined purpose. As such, pragmatics and discourse are related in that pragmatics are the means by which the purpose of discourse is achieved.
Both pragmatics and discourse involve concepts far deeper than mere word definitions and sentence structure. Unlike grammar, which involves the rules governing proper language structure, pragmatics and discourse focus on the meaningfulness of spoken or written language. Whether storytelling, explaining, instructing, or requesting, a speaker or writer has an intended purpose for communicating. How a speaker or writer constructs sentences to meet his intended purpose involves both pragmatics and discourse.
For example, there are several ways to warn a person about the risk of burns associated with a hot surface. The process of explaining the concept must follow a logical order to be understood by listeners. A speaker might change the wording of such explanations, depending on the age and developmental ability of listeners. Determining the order of the explanation is discourse, whereas determining how to word the explanation for different audiences is pragmatics.
Pragmatics and discourse go hand-in-hand with context. Changing the language used for an audience is an integral part of pragmatics, but can easily affect context clues and thus, affect discourse. Sentences changed too much or taken out of context lose the ability to further a conversation. Without the necessary information preceding or following a particular sentence, its meaning can easily be lost. Such omissions affect the cohesiveness of a conversation or text, thus making it difficult to maintain common understandings.
Likewise, failure to follow the social rules of pragmatics can drastically affect discourse. Although not necessarily rules in the same sense as grammar, the rules of pragmatics include such concepts as allowing both speaker and listener time to express ideas, expanding on or rephrasing ideas to increase understanding, or choosing words to best fit the speaker's purpose. If a speaker is requesting something, for example, a poor choice of words can make the request sound more like a demand. Alternatively, complex sentence structure or an overly long explanation can undermine the purpose of discourse by making it impossible for listeners or readers to follow along.