H. Paul Grice (1913–1988) is most famous for his doctrine of conversational implicature that he introduced in 1968. This doctrine was developed as a logical thesis about the “if-then” conditional, but its applications to understanding linguistic usage go beyond its original technical purpose. Grice demonstrated that the meanings of words used in sentences, and the sentences themselves, are highly dependent on the context of utterance, as well as certain rules of cooperation in speech. These rules include: be informative, do not be more informative than required, do not state what you know is false, do not state what you have no evidence for, be relevant, do not be obscure, do not be ambiguous, do not use more words than you must, and observe order.

When speakers break one or more of these rules, the result is that what speakers say is not always equivalent to the literal meaning of their words. For example, if a speaker is asked how a play was and responds that the furniture used in the set was very nice, this irrelevance will imply a negative judgment of the play.

Grice developed his speech theory with considerable complexity, and it is of interest to logicians and analysts of language. Grice was thus was able to demonstrate the existence of a lot of linguistic structure—with possibilities for neatly implied alternative meanings in contexts of conversation. This was a huge setback to the confidence of ordinary language analysts that meandering investigations of overlapping linguistic practices could yield stable meanings for certain words. Grice showed that meaning depends on context. But on the other hand, Grice’s work emphasizes the complexity of ordinary language as life practices, similar to self contained games, like baseball, but unlike baseball, capable of adding meaning to the most important events in our existence. Grice’s writings have been collected and published as Philosophical Grounds of Rationality (1986), Studies in the Ways of Words (1989), and Aspects of Reason (2001).