tautology
What does "tautology" mean?
A tautology is a statement that is true by necessity of its logical form, or more commonly, a redundant expression where the same idea is repeated using different words. Imagine someone saying, "I saw it with my own eyes"—since you cannot see with anything else, the phrase "with my own eyes" is a tautology that adds no new information to the sentence. In logic, it refers to a proposition that is true under every possible interpretation. In everyday language, however, it is often treated as a stylistic error or a "circular argument." You will most frequently encounter this term in philosophy, computer science, or when critiquing writing for unnecessary wordiness.
"tautology" in conversation
Writing workshop critique
You've used a tautology here: 'free gift.'
You've used a tautology here: 'free gift.'
Oh, I see. A gift is already free by definition, right?
Oh, I see. A gift is already free by definition, right?
'Free gift' is a classic example of a tautology because a gift implies no cost.
Debating philosophy
Is 'either it will rain or it won't' considered a tautology?
Is 'either it will rain or it won't' considered a tautology?
Exactly. It is a logical certainty that covers all possibilities.
Exactly. It is a logical certainty that covers all possibilities.
Logical tautologies are statements that cannot be false.
"tautology" in a sentence
The ATM machine is broken.
The ATM machine is broken.
His argument was a tautology, as he simply repeated the premise in the conclusion.
His argument was a tautology, as he simply repeated the premise in the conclusion.
The statement 'all bachelors are unmarried' is a classic linguistic tautology.
The statement 'all bachelors are unmarried' is a classic linguistic tautology.
