Ipse dixit

An assertion without proof

Ipse dixit is a Latin phrase which means "He, himself, said it".

Cicero coined the phrase Ipse dixit, "He, himself, said it"

In logic, ipse dixit is known as the bare assertion fallacy.[1] One form of the fallacy may be summarized as follows:

  • Fact 1: X claims statement A.
  • Fact 2: X claims that X is not lying.
  • Conclusion: Therefore, A is true or false or whatever X claims it is.

A bare assertion denies that an issue is debatable. In other words, that's just the way it is.[2] In Alice in Wonderland, the problem of ipse dixit is explained by example.[3]

    "When I use a word," Humpty Dumpty said, in rather a scornful tone, "it means just what I choose it to mean—neither more nor less."
    "The question is," said Alice, "whether you can make words mean so many different things."

    "The question is," said Humpty Dumpty, "which is to be master      that's all."[4]

The most basic way to distort an issue is to deny that it exists.[5]

Ipse dixit is used to identify and describe a dogmatic statement which the speaker expects the listener to accept as valid.[6] Ipse dixit is a sort of arbitrary dogmatism.[7] The only proof we have of the fact is that this person said it.[8]

The theory of ipse dixit involves that an unproven statement that the speaker claims is true because it was uttered by "an authority" on the subject. The opinion may carry some weight based solely on the authority or standing of the person said it.[9]



In the De natura deorum (On the Nature of the Gods), the Roman writer Cicero (106–43 BC) coined the term ipse dixit as an error in law.[10] Cicero was describing the students of Pythagoras.[11]

Jeremy Bentham changed the term ipse-dixit into the word ipse-dixitism.[12] He created this term to apply to political arguments.[13]

Ipse dixit is made specific in American law. For example, in a 1997 case, the US Supreme Court recognized the problem of "opinion evidence which is connected to existing data only by the ipse dixit of an expert".[14]



  1. "Bare assertion fallacy" at Findthedata.org[permanent dead link]; retrieved 2012-12-10.
  2. Sebranek, Patrick et al. (2011). Write 1, p. 173.
  3. Filan, Patrick J. "Opinions Must Be Based On Facts: Unlike Humpty Dumpty, witnesses can't make unproven assertion,"[permanent dead link] Connecticut Law Journal, Vol. 37, No. 46 (November 14, 2011) citing Through the Looking Glass; retrieved 2012-12-11.
  4. Caroll, Lewis. (2000). The Annotated Alice: Alice's Adventures in Wonderland & Through the Looking Glass, p. 213[permanent dead link].
  5. VanderMey, Randall et al. (2011). Comp, p. 183.
  6. Whitney, William Dwight. (1906). "Ipse dixit," The Century dictionary and cyclopedia, pp. 379-380.
  7. Westbrook, Robert B. "John Dewey and American Democracy," p. 359.
  8. "Ipse dixit at Law.com; retrieved 2012-12-10.
  9. "Ipse dixit" at Nolo.com; retrieved 2012-12-10.
  10. Poliziano, Angelo. (2010). Angelo Poliziano's Lamia: Text, Translation, and Introductory Studies, p. 26; excerpt, "In Cicero's De natura deorum, as well as in other sources, the phrase “Ipse dixit” pointed to the notion that Pythagoras's disciples would use that short phrase as justification for adopting a position: if the master had said it, it was enough for them and there was no need to argue further."
  11. Benthem, Jeremy. (1838). Works of Jeremy Bentham, Vol. 1, Part 2, p. 467; excerpt, "Ipse dixit is an expression that took its rise from the ... the disciples of Pythagoras"
  12. Benthem, Jeremy. (1834). Deontology; or, The science of morality, Vol. 1, p. 323; excerpt, "ipsedixitism ... comes down to us from an antique and high authority, —-it is the principle recognised (so Cicero informs us) by the disciples of Pythagoras. Ipse (he, the master, Pythagoras), ipse dixit, -—he has said it; the master has said that it is so; therefore, say the disciples of the illustrious sage, therefore so it is."
  13. Benthem, Jeremy. (1838). Works of Jeremy Bentham, p. 192; excerpt, "... it is not a mere ipse dixit that will warrant us to give credit for utility to institutions, in which not the least trace of utility is discernible."
  14. Filan, citing General Electric Co. v. Joiner, 522 U.S. 136, 137; 118 S.Ct. 512; 139 L.Ed.2d 508 (1997).