Pragmatics is an area of linguistics that I love, but which is difficult to define. Witness Mr. Paul Levinson, who spent an entire chapter trying to separate it from semantics in his textbook. Argh!
So what is Pragmatics? Basically, it deals with those areas of meaning which aren't really meaning. What does that mean? It deals with implications (in the lingo, "implicature"), and with presuppositions, and with using language to do things rather than just send messages.
I think most people know about presuppositions, even if they can't give a name to them. An example would be when the lawyer asks the plaintiff,
"Have you stopped beating your wife?"
Either a yes or no answer will contain the presupposition that the plaintiff beat his wife. Thus, in order to avoid tacit acceptance of the idea that he's beaten his wife, the plaintiff has to reject the question. There are many words like this. "Manage to," for example, which presupposes that the person has "tried to."
The usefulness of presuppositions in story-writing lies in their ability to carry extra implied meaning. If you say that your character "didn't do" something, we know nothing about whether he or she wanted to do that thing, or tried. "Didn't manage to do" tells us a heck of a lot more in just two additional words. So keep an eye out for these as helpers in the creation of point of view as well as ways to layer meaning into your story.
If you've followed my blog for any length of time you'll have noticed that I've talked about H.P. Grice and the Cooperative Principle more than once. Essentially the Cooperative Principle says, "make your contribution to the conversation optimally relevant and appropriate." This may seem terribly obvious, but it is in fact quite powerful. This is because the assumption of cooperativeness allows us to draw conclusions from what people say.
Let's say someone tells you "I have two children." From the point of view of strict truthfulness, this could be true so long as that person had two or more children. But the Cooperative Principle lets us conclude that if the person had more than two children, they would be telling us that. Thus, we conclude that the person has two, and only two, children. Grice calls this the "maxim of quantity."
There are other Gricean maxims, but I won't go into all of them here. I'll just mention that the "maxim of quality" means that you're not lying (I'll return to the issue of lying, and its implications in stories, in a minute).
I've probably also mentioned "speech acts." These are instances of "doing by speaking," as when you invite, insult, refuse, swear, promise, marry, etc.. The action is accomplished by the utterance of the speech. I encourage you to think about these, because they often have social consequences. What kind of unique speech acts might a world have? In what contexts might they occur? What are the special conditions required for the act to be performed successfully (you can't marry two people to one another unless you possess special qualifications, for example)?
In my story, "Let the Word Take Me", every utterance was an act - an act of holy transport or blasphemy, or of respectful restraint - and was restricted by special conditions of person, time and place. This is an extreme example of the type, but there is a lot of interesting stuff to be gained by playing with speech acts in alternate cultural scenarios.
The other issue that Pragmatics covers is that of Politeness. This is extremely rich ground for story ideas, especially because Politeness often conflicts directly with the Gricean Maxims. In particular, it's easy to misinterpret polite avoidance of particular topics as evasiveness or lying. We do a lot of effortful things in order to avoid threatening other people's "face," also called committing "face-threatening acts." Brown and Levinson 1987 is the classic source of this discussion.
Interestingly, Brown and Levinson talk about two types of social desires: the desire to be autonomous (negative face), and the desire to be accepted (positive face). These contrast with one another, and while polite and diffident talk addresses another person's desire to be autonomous, that desire may not be foremost in their minds. Familiar talk (including slang and insider vocabulary) addresses another person's desire to be accepted. The choice between these two strategies is critical to a person's success.
The other reason I love pragmatics as a source for stories is this: when people are learning foreign languages, the errors they make in pronunciation, word formation or sentence word order - even picking the wrong word meaning - are interpreted as errors in language. They are easily excused as the broken language of a learner. Errors in pragmatics, however, are not seen as language errors. They reflect instead on the personality and identity of the speaker. So a person who makes a politeness error is less likely to be seen as a learner and more likely to be seen as rude.
I have to say that Pragmatics is my favorite source for story ideas. I hope this discussion has shown you why, and has given you some ideas for exploring pragmatics in your own story worlds.