factive

A factive is a type of verb in linguistics whose embedded clause is presupposed to be true. In English, common factive verbs include know, realize, be aware of, discover, find out, regret, be certain, and prove. For example, in the sentence I know that the store is closed, the speaker treats the proposition that the store is closed as true, and the verb encodes the speaker’s knowledge.

Factivity works through presupposition: the truth of the embedded proposition is assumed, even if the sentence as a whole is negated or questioned. This contrasts with non-factive verbs such as think or suppose, which do not entail the truth of their complement. For instance, I think that the store is closed does not by itself commit to the store being closed.

The semantic effect of factive verbs can influence discourse interpretation and updating of common ground. Because the embedded clause is presupposed, it tends to constrain what counts as shared knowledge in a conversation. Some languages mark factivity differently or with different lexical items, but the core idea—that the action described by the verb presupposes the truth of its complement—appears in many languages.

See also: presupposition, implicature, entailment, non-factive verbs. Further discussions often distinguish strict factives (which reliably presuppose truth) from less strict or context-dependent cases, and explore how tense, negation, and modality interact with factive meaning.