Tautology — From Greek to English | etymologist.ai
tautology
/tɔːˈtɒl.ə.dʒi/·noun·1574·Established
Origin
From Greek tautologia ('saying the same thing'), built on tauto- ('the same') and -logia ('saying') from PIE *leǵ- ('to gather/speak'), tautology names redundant repetition in rhetoric but necessary truth in logic — a word whose own doubled structure performs the very sameness it describes.
Definition
A statement or formula that is true by necessity or by virtue of its logical form, from Greek tautologia, combining tauto- (the same) and -logia (speaking), from PIE *leǵ- (to gather, to speak).
The Full Story
Greek5th century BCEwell-attested
Tautology derives from the Greek tautologia (ταυτολογία), meaning 'saying the same thing,' formed from tauto- (ταὐτό, 'the same') and -logia (-λογία, 'saying, discourse'). The element tauto- is a contraction of to auto (τὸ αὐτό, 'the same thing'), combining the neuter article to with the reflexive/identity pronoun auto. The suffix -logia comes from legein (λέγειν, 'to say, to speak'), itself from logos (λόγος, 'word
Did you know?
Theword tautology is itself tautological in structure. Its two halves — tauto- ('the same') and -logia ('a saying') — both point at sameness and repetition, making the word a miniature performance of its own meaning. Meanwhile, its PIE root *leǵ- ('to gather') split so thoroughly between Latin and Greek that a catalogue (things gathered into a list) and a dialogue (speech passing between people) are etymological cousins — the physical act of picking up objects and the abstract act of constructing
this rhetorical sense of vain repetition. In the 19th and 20th centuries, formal logic adopted the word with a distinct technical meaning: a tautology became a proposition or formula that is true under every possible interpretation, true by virtue of its logical form alone rather than its content — as in 'either it is raining or it is not raining.' The deeper Proto-Indo-European roots are *só (demonstrative pronoun, 'this, that'), which gave rise to the Greek article to and survives in English 'the' and 'that,' and *leǵ- (to gather, to pick out, to speak), which produced an extraordinary family of descendants: Greek legein yielded logos, and through Latin legere ('to read, to gather') and its derivatives, English inherited logic, lexicon, dialogue, lecture, legend, legal, legitimate, lesson, logarithm, and catalogue. The root *leǵ- thus encodes the ancient conceptual link between gathering, selecting, and articulate speech — the act of picking words is the act of speaking. Key roots: *só (Proto-Indo-European: "demonstrative pronoun: this, that"), *leǵ- (Proto-Indo-European: "to gather, to pick out, to speak"), tauto- (Ancient Greek: "the same (contraction of to auto)"), -logia (Ancient Greek: "saying, discourse, study (from legein)").