1.3. Beyond saying: pragmatics

1.3.0. Overview

Our study of logic will be limited to deductive logic; and, even within those bounds, we will consider only the logical forms that are part of first-order logic. These limits imply some others that deserve consideration in their own right: although our study of deductive logic can be seen as the study of meaning, we will not study all aspects of meaning.

1.3.1. A model of language
One simple picture of language sees it as a device for conveying information by way of the propositions expressed by sentences.

1.3.2. Some complications
According to this picture, the meaning of a sentence lies in the way its truth value varies among possible worlds. But the truth value is not the only feature of sentences that is important for meaning, and the state of the world is not the only factor on which the truth value depends.

1.3.3. Speech acts
Questions and commands do not appear to convey propositions, and even declarative sentences may play roles other than assertion.

1.3.4. Implicature
Communication often exploits the assumption that what a speaker says is not only true but satisfies certain other requirements.

1.3.5. Indexicality
When a sentence conveys a proposition, the proposition that is conveyed will usually depend on the context in which the sentence is used, and sentences are sometimes designed to convey information about his context.

1.3.6. Vagueness
The range of application of many terms will have fuzzy boundaries even in a given context, and sentences that apply them to things falling in this gray area may have no determinate truth value.

1.3.7. Presupposition
Another way of conveying information rests on the preconditions for a sentence to have a truth value at all.