Word
Tautology
In logic, a statement true under every interpretation of its parts; in ordinary speech, needless repetition of the same idea
Examples
“The account is open or it is not open” is true before anyone checks the account.
“A widow whose spouse has died” is a tautology in everyday speech because “widow” already says it.
Origin
From Greek tauto, “the same,” and logos, “word” or “statement.” English first used the term for needless repetition. In 1921, Ludwig Wittgenstein gave it its modern logical role: a proposition true under every assignment of truth values.
How it connects
The name for a statement that is always true, and therefore risks nothing about the world.
This word appeared in When certainty says nothing, the Involves connection for August 6, 2026, which asked: What can a statement tell you if nothing could prove it wrong?
Check yourself
Which statement is a tautology in the logical sense?
“The account is open or it is not open.”. Right. It is true before anyone checks the account, because nothing about the world could make it false.
What the sources establish
Tautology combines Greek tauto, “the same,” with logos, “word” or “statement,” and entered English for needless repetition before taking a precise logical sense.
In the Tractatus, Wittgenstein treats a tautology as a proposition true under every assignment of truth values.
Sources
Tractatus Logico-Philosophicus (Ludwig Wittgenstein, 1922), Propositions 4.46–4.463 (tautology and contradiction)
tautology (Online Etymology Dictionary), Entry for “tautology”: Greek tauto and logos