proof by contradiction

English - English

Definition of proof by contradiction in English English dictionary

A proof of the following sort (1): It is desired to prove A, so assume that A is not true, and derive a contradiction from this assumption. From this it follows that "not A" implies falsity, in other words "not not A" is true. From the law of double negation, it follows that A is true. Also, a proof of the following sort (2): It is desired to prove "not A", so assume that A is true, and derive a contradiction. From this it follows that A implies falsity, in other words "not A". Both sorts of proof are valid in classical logic but only the second sort is valid in intuitionistic logic.http: //plato.stanford.edu/entries/logic-intuitionistic/

Hyphenation

proof by con·tra·dic·tion

Turkish pronunciation

pruf bay käntrıdîkşın

Synonyms

reductio ad absurdum

Pronunciation

/ˈpro͞of ˈbī ˌkäntrəˈdəksʜən/ /ˈpruːf ˈbaɪ ˌkɑːntrəˈdɪkʃən/