Entailment (linguistics)

Linguistic entailments are entailments which arise in natural language. If a sentence A entails a sentence B, sentence A cannot be true without B being true as well.[1] For instance, the English sentence "Pat is a fluffy cat" entails the sentence "Pat is a cat" since one cannot be a fluffy cat without being a cat. On the other hand, this sentence does not entail "Pat chases mice" since it is possible (if unlikely) for a cat to not chase mice.

Entailments arise from the semantics of linguistic expressions.[2] Entailment contrasts with the pragmatic notion of implicature. While implicatures are fallible inferences, entailments are enforced by lexical meanings plus the laws of logic.[3] Entailments also differ from presuppositions, whose truth is taken for granted. The classic example of a presupposition is the existence presupposition which arises from definite descriptions. For instance, the sentence "The king of France is bald" presupposes that there is a king of France. Unlike an entailment, presuppositions survive when the sentence is negated. For instance, "The king of France is not bald" likewise presupposes that there is a king of France.[3]