TERMIUM Plus^®

Fiche 1,  Justifications,  Anglais

Record number: 1, Textual support number: 1 CONT

The general principle is that any assumption that leads you to a contradiction must be false. Thus, if you can deduce a contradiction (using valid rules of inference) from a certain assumption, it is legitimate to conclude that the assumption is false. Indirect proof is an extremely useful method, both in logic and in the real world. In real world arguments, if you can start from your opponent's premises and derive a contradiction from them (which is frequently possible), it is a very powerful refutation of the opponent's position. It is because of the usefulness of IP (indirect proof) that I have decided to introduce it right away.  1, fiche 1, Anglais, - indirect%20proof

Fiche 1,  Justifications,  Français

Record number: 1, Textual support number: 1 CONT

Toute proposition est vraie ou fausse (principe du tiers exclu) et 2° la double négation d'une assertion correspond à sa vérité. La combinaison de ces deux corollaires recèle un mode d'inférence, la méthode de preuve indirecte, qui permet de démontrer des théorèmes d'existence mathématiques sur la simple base de leur non-contradiction.  1, fiche 1, Français, - preuve%20indirecte

Fiche 1,  Justifications,  Espagnol