tautology (grammar, rhetoric, and logic)

Glossary of Grammatical and Rhetorical Terms

"A tautology is empirically empty," says Robert Henry Peters, "because it tells us nothing new about the world around us" (A Critique for Ecology, 1991).


(1) In grammar, a tautology is a redundancy (sense #3)--in particular the needless repetition of an idea using different words. (Repetition of the same sense is tautology. Repetition of the same sound is tautophony.)

(2) In rhetoric and logic, a tautology is a statement that is unconditionally true by virtue of its form alone--for example, "You're either lying or you're not." Adjective: tautologous or tautological.

See Examples and Observations below. Also see:

From the Greek, "redundant"

Examples and Observations

  • "It took only as many minutes to find the following half-dozen examples in one day's crop of papers:
    A major nuclear disaster could have been sparked off . . .

    . . . who died of a fatal dose of heroin

    . . . equalized the game to a 2-2 draw

    . . . kept it from his friends that he was a secret drinker

    Dirty Den has made up his mind never to go back to EastEnders, finally severing his connection with the soap

    . . . a group for one-parent single mothers
    Tautology is either unnecessary elaboration (the Inland Revenue's white-collar workers), pointless repetition (pair of twins), superfluous description (Europe's huge butter mountain), a needless appendage (weather conditions) or a self-cancelling proposition (He is either guilty or not guilty)."
    (Keith Waterhouse, Waterhouse on Newspaper Style, rev. ed. Revel Barker, 2010)
  • "At the risk of being redundant and repetitive, and redundant, let me say that tautology is the last thing children need from their parents, especially when they are in trouble.

    "Whatever you have to say, whatever you do, avoid tautology. Try to say it only once!"
    (Tom Sturges, Parking Lot Rules & 75 Other Ideas for Raising Amazing Children. Ballantine, 2009)
  • "The 'new public management' has brought new ailments, particularly tautology. You often see such phrases as 'first class organizations are those that perform excellently.'"
    (David Walker, "Mind Your Language." The Guardian, Sep. 27, 2006)
  • Mark Twain on Tautological Repetition
    "I do not find that the repetition of an important word a few times--say, three or four times--in a paragraph troubles my ear if clearness of meaning is best secured thereby. But tautological repetition which has no justifying object, but merely exposes the fact that the writer's balance at the vocabulary bank has run short and that he is too lazy to replenish it from the thesaurus--that is another matter. It makes me feel like calling the writer to account."
    (Mark Twain, Autobiography of Mark Twain. University of California Press, 2010)
  • Tautologies in Logic
    - "In common parlance, an utterance is usually said to be tautologous if it contains a redundancy and says the same thing twice over in different words--e.g., ' John is the father of Charles and Charles is a son of John.' In logic, however, a tautology is defined as a statement that excludes no logical possibilities--'Either it is raining or it is not raining.' Another way of putting this is to say that a tautology is 'true in all possible worlds.' No one will doubt that, irrespective of the actual state of the weather (i.e., regardless of whether the statement that it is raining is true or false), the statement 'Either it is raining or it is not raining' is necessarily true."
    (E. Nagel and J. R. Newman, Gödel's Proof, 1958)

     - "A tautology is a statement that is logically, or necessarily, true or is so devoid of content as to be practically empty (and thus true because completely empty statements, making no claim, cannot be false). Example: 'Scott Peterson did it or he didn't.'"
    (Howard Kahane and Nancy Cavender, Logic and Contemporary Rhetoric, 10th ed. Thomson Wadsworth, 2006)

    - "Tautology. Yes, I know, it's an ugly word. But so is the thing. Tautology is this verbal device which consists in defining like by like . . .. Since it is magical, it can of course only take refuge behind the argument of authority: thus do parents at the end of their tether reply to the child who keeps on asking for explanations: 'because that's how it is,' or even better: 'just because, that's all.'"
    (Roland Barthes, Mythologies. Macmillan, 1972)
  • Tautology as a Logical Fallacy
    "One of the most boring fallacies, the tautology, basically just repeats the premise.
    FAN: The Cowboys are favored to win since they're the better team."
    (Jay Heinrichs, Thank You for Arguing: What Aristotle, Lincoln, and Homer Simpson Can Teach Us About the Art of Persuasion. Three Rivers Press, 2007)

Pronunciation: taw-TOL-eh-jee

Also Known As: pleonasm