Contra principia negantem non est disputandum
Contra principia negantem non est disputandum (Latin, alternatively Contra principia negantem disputari non potest and Contra principia negantem disputari nequit; literally, "Against one who denies the principles, there can be no debate") is a principle of logic and law: in order to debate reasonably about a disagreement, there must be agreement about the principles or facts by which to judge the arguments.
The maxim cannot be found in Aristotle, though scholars have pointed to some Aristotelian passages that approach it in spirit. It is sometimes said to have been used in Medieval scholastic philosophy to refer to the authority of the Aristotelian system. Duns Scotus concludes one passage of his commentary on Peter Lombard's Sentences with the statement, "If this argument is not convincing, many principles supposed by the philosophers are called into doubt; and against one who denies commonly accepted principles, discussion is impossible (contra autem negantem principia communiter recepta, non est disputandum).
Arthur Schopenhauer refers to it in his "The Art of Controversy," and Lenin objected to Peter Berngardovich Struve's assertion of the principle, retorting, "That depends on how these principia are formulated—as general propositions and notes, or as a different understanding of the facts of Russian history and present-day reality." Karl Popper thought the maxim expressed the relativist's irrationalist "doctrine of the impossibility of mutual understanding between different cultures, generations, or historical periods – even within science, even within physics": "The myth of the framework is clearly the same as the doctrine that one cannot rationally discuss anything that is fundamental, or that a rational discussion of principles is impossible."
- Joseph Agassi, Science and its history: a reassessment of the historiography of science, Springer, 2008, p. 310
- Hans Günter Zekl, Aristoteles: Metaphysik, Würzburg: Königshausen & Neumann, 2003, p. 26
- Joannis Duns Scoti doctoris subtilis, ordinis minorum opera omnia, editio nova, vol. 16, Paris, 1894, p. 93
- Coke, Sir Edward; et al. (1832). The first part of the Institutes of the laws of England. p. 66. Retrieved 2010-06-15.
A maxime [in law] is a proposition, to be of all men confessed and granted without proofe, argument, or discourse. Contra negantem principia non est disputandum.
- Schopenhauer, Arthur (1896). tr. Bailey Saunders, ed. The Art of Controversy. p. 15. Retrieved 2010-06-15.
In every disputation or argument on any subject we must agree about something; and by this, as a principle, we must be willing to judge the matter in question. We cannot argue with those who deny principles. Contra negantem principia non est disputandum.
- Vladimir I. Lenin, The Economic Content of Narodism and the Criticism of It in Mr. Struve's Book, in Collected Works, 4th English Edition, Moscow: Progress Publishers, 1972, p. 433 n.
- Karl Popper, "The Myth of the Framework," in The Myth of the Framework: In defence of science and rationality, London: Routledge, 1994, pp. 33, 59