Factivity

Factivity is a semantic property of certain predicates—especially verbs, and sometimes adjectives and other predicates—in which the truth of the proposition embedded in the clause is entailed by the main clause. When a sentence contains a factive verb, its asserted content commits the speaker to the truth of the embedded proposition. This contrasts with non-factive predicates, where the embedded content need not be true even if the main clause is.

Commonly cited factive verbs include know, realize, discover, prove, and remember. Examples: “John knows that the earth orbits the Sun” and “Mary remembered that the meeting was at 3” imply that the embedded propositions are true. Factive adjectives include certain and sure: “It is certain that the hypothesis is correct” likewise asserts the truth of the embedded claim. Other factive expressions arise in constructions such as “It turned out that” or “the data show that.”

Factivity is often discussed in contrast to non-factivity in attitude reports. For instance, “John thinks that P” does not guarantee P is true, whereas “John knows that P” does. The distinction has consequences for reasoning about negation and evidential support: negating a factive verb (e.g., “John does not know that P”) does not by itself negate P, but the factive reading still binds P to be true if the sentence is true.

In linguistic typology and philosophy of language, factivity helps explain how speakers encode epistemic commitment and how truth conditions are projected through embeddings. Some languages encode factivity more explicitly in their verbs or mood systems.