Compositionality

A language is compositional if the meaning of each of its complex expressions (for example, ‘black dog’) is determined entirely by the meanings its parts (‘black’, ‘dog’) and its syntax. Principles of compositionality provide precise statements of this idea. A compositional semantics for a language is a (finite) theory which explains how semantically important properties such as truth-conditions are determined by the meanings of parts and syntax. Supposing English to have a compositional semantics helps explain how finite creatures like ourselves have the ability to understand English’s infinitely many sentences. Whether human languages are in fact compositional, however, is quite controversial.