• Tautology


    • US IPA: /tɔˈtɒl.ə.dʒi/


    From Late Latin tautologia, from Ancient Greek ταυτολογία from ταὐτός (tautós, "the same") + λόγος (lógos, "explanation")

    Full definition of tautology



    (countable and uncountable; plural tautologys)
    1. (uncountable) redundant use of wordsIt is tautology to say, "Forward Planning".
    2. (countable) An expression that features tautology.''The expression "raze to the ground" is a tautology, since the word "raze" includes the notion "to the ground".
      • 1946, Bertrand Russell, History of Western Philosophy:Pure mathematics consists of tautologies, analogous to ‘men are men’, but usually more complicated.
    3. (countable, logic) A statement that is true for all values of its variablesGiven a Boolean A, "A OR (NOT A)" is a tautology.A logical statement which is neither a tautology nor a contradiction is a contingency.A tautology can be verified by constructing a truth tree for its negation: if all of the leaf nodes of such truth tree end in X's, then the original (pre-negated) formula is a tautology.


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