Ipse Dixit

The Latin phrase, meaning "he said it himself," comes from Roman orator Marcus Tullius Cicero (106–43 BC) in De Natura Deorum (On the Nature of the Gods), translating Greek autòs épha—an argument from authority used by Pythagoras's disciples. Medieval scholastics applied it to Aristotle's statements. The earliest English evidence is from 1574 (John Whitgift). Jeremy Bentham coined "ipse-dixitism" in the late 18th century for non-utilitarian political arguments. Modern legal usage employs it to critique authority-based arguments.