tautology

American  

[taw-tol-uh-jee] / tɔˈtɒl ə dʒi /

noun

plural

tautologies

1. needless repetition of an idea, especially in words other than those of the immediate context, without imparting additional force or clearness, as in “widow woman.”

2. an instance of such repetition.

3. Logic.

   1. a compound propositional form all of whose instances are true, as “A or not A.”

   2. an instance of such a form, as “This candidate will win or will not win.”

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tautology British  

/ ˌtɔːtəˈlɒdʒɪkəl, tɔːˈtɒlədʒɪ /

noun

1. the use of words that merely repeat elements of the meaning already conveyed, as in the sentence Will these supplies be adequate enough? in place of Will these supplies be adequate?

2. logic a statement that is always true, esp a truth-functional expression that takes the value true for all combinations of values of its components, as in either the sun is out or the sun is not out Compare inconsistency contingency

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Usage

What does tautology mean? A tautology is the unnecessary repetition of an idea, statement, or word whose meaning has already been expressed, as in 8 a.m. in the morning. (The label a.m. indicates the morning, so in the morning creates a tautology). Tautologies say the same thing twice without adding new information or emphasis. In logic, tautology has a more specific meaning: a statement that is always true, as in Statement 1 is true or not true or Either we will arrive on time or we will not arrive on time.  Example: My professor pointed out that the phrase “evening sunset” is a tautology because sunsets always happen in the evening.

Other Word Forms

• tautologic adjective
• tautological adjective
• tautologically adverb
• tautologist noun
• tautologous adjective

Etymology

Origin of tautology

First recorded in 1570–80; from Late Latin tautologia, from Greek tautología “repetition of something already said” (a term in rhetoric); tauto-, -logy

Explanation

Tautology is useless restatement, or saying the same thing twice using different words. “Speedy sprint" is a tautology because sprint already means "speedy running." The noun tautology originates from the Greek word tautologos, meaning “repeating what is said.” "A pedestrian traveling on foot" is a tautology because a pedestrian, by definition, is someone who walks. In the study of logic, a tautology is a statement that is necessarily true under any interpretation and cannot be denied without introducing logical inconsistencies. "It will snow tomorrow, or it will not snow tomorrow" is an example. No argument here — it's true any way you look at it.

Example Sentences

On one level, this is a fairly ridiculous tautology.

From Los Angeles Times • May 14, 2024

The anthropic principle is a tautology masquerading as a truth, but it has proved remarkably resilient.

From Scientific American • Sep. 27, 2021

The McSmiths are also undeterred by the seeming tautology of presenting comic reinterpretations of comedies.

From New York Times • Aug. 5, 2021

A: “Family is family” isn’t really an argument so much as a tautology.

From Slate • Jul. 21, 2020

“That’s not exactly a tautology, but it is funny. You have a singular wit.”

From "The Absolutely True Diary of a Part-Time Indian" by Sherman Alexie

Related Words

• litany
• recurrence
• reiteration
• repeat
• rhythm