Ipse dixit

[3] The Latin form of the expression comes from the Roman orator and philosopher Marcus Tullius Cicero (106–43 BC) in his theological studies De Natura Deorum (On the Nature of the Gods) and is his translation of the Greek expression (with the identical meaning) autòs épha (αὐτὸς ἔφα), an argument from authority made by the disciples of Pythagoras when appealing to the pronouncements of the master rather than to reason or evidence.

[7] In modern legal and administrative decisions, the term ipse dixit has generally been used as a criticism of arguments based solely upon the authority of an individual or organization.

1974), Circuit Judge Wilkey considered that the Secretary of Transportation's "statement of the reasons for his conclusion that the requirements are practicable is not so inherently plausible that the court can accept it on the agency's mere ipse dixit.

"[8] In 1997, the Supreme Court of the United States recognized the problem of "opinion evidence which is connected to existing data only by the ipse dixit of an expert.

"[10] "[W]hen you come across an argument that you recall the majority took issue with," U.S. Supreme Court Justice Elena Kagan advised readers of her dissent in 2023's Andy Warhol Foundation for the Visual Arts, Inc. v. Goldsmith, "go back to its response and ask yourself about the ratio of reasoning to ipse dixit.