On this definition, for someone to know X, it is required that X be true. A linguistic question thus arises regarding the usage of such phrases: does a person who states “John knows X” implicitly claim the truth of X?

Steven Pinker explored this question in a 2007 book on language and cognition, using a widely publicized example of a 2003 speech by George W. Bush that included the line, “British Intelligence has learned that Saddam Hussein recently sought significant quantities of uranium from Africa.” Over the next few years, it became apparent that this intelligence lead was incorrect. But the way the speech was phrased, using a factive verb, implicitly framed the lead as truth rather than hypothesis. The proposition that relational predicates having to do with knowledge, such as knows, learn, remembers, and realized, presuppose the factual truth of their object.

  • Adam regrets drinking Mike’s home brew.
    Factive Verb: Adam drank Mike’s home brew.
  • Wendy was aware that Rick was there.
    Factive Verb: Rick was there.
  • Ted realized that Joe was in debt.
    Factive Verb: Joe was in debt.
  • It was odd how proud he was.
    »He was proud.

Some further factive predicates: know; be sorry that; be proud that; be indifferent that; be glad that; be sad that.