(redirected from tautologically)
Also found in: Dictionary, Thesaurus, Legal.


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



(1) The repetition of the same word or of words close in meaning: also, an example of such repetition. Examples are iasnee iasnogo (“completely obvious”; literally, “clearer than clear”) and plachet, slezami zalivaetsia (“she weeps, dissolved in tears”). In poetic language, especially in oral folk poetry, tautology is used to intensify emotional effect. An example in the bylina (epic folk song) about Nightingale the Robber is Pod Chernigovom silushki chernym-cherno, I Chernym-cherno, chernei vorona (“Near Chernigov the troops looked black as could be [literally, ‘black-black’], / Black as could be, blacker than a raven”). Poets often use tautology and tautological rhymes; an example is Pushkin’s Vot na bereg vyshli gosti, / Tsar’ Saltan zovet ikh v gosti (“The visitors disembarked, / Tsar Saltan invited them to visit”).

A number of tautological word groups are widely used in colloquial speech, for example, tselikom i polnost’iu (“wholly and completely”), k segodniashnemu dniu (“by today”; literally, “by today’s day”) and den’-den’skoi (“the livelong day”). Unnecessary repetitions in speech sometimes testify to a speaker’s limited command of language. Tautology is a type of pleonasm.


(2) In logic, an extreme example of the logical fallacy of the unwarranted premise (Latin petitio principii), namely, the definition or proof of something by the same thing (Latin idem per idem). In two-valued classical logic the term “tautology,” like the term “law of logic,” refers to reliable, always true, or identically true formulas that remain constant in relation to their constituent variables, that is, in relation to the world’s actual state of affairs. In this type of logic, according to G. W. von Leibniz, tautologies are truths in all possible worlds, eternal truths, essential truths, and truths by virtue of the postulates of classical logic. An example of this type of tautology is the law of the excluded middle.

In many-valued logic, a tautology is a formula which in any set from an accepted universal system of values for variables retains the same distinctive value. This type of tautology is used in proofs of independence.


Wittgenstein, L. Logiko-filosofskii traktat. Moscow, 1958. (Translated from German.)
Church, A. Vvedenie v matematicheskuiu logiku, vol. 1. Moscow, 1960. (Translated from English.)



A proposition which is always true.

Compare: paradox.

The Linguistic Smarandache Tautologies,.
References in periodicals archive ?
It should come as some comfort that our Constitution recognizes and protects substantive rights that have evolved throughout the nation over time--rights such as the right to vote in a state election that we all but tautologically accept under our modern constitutional conception.
A supertautology thus limits reality to just that over which it distributes (including itself); anything over which it does not distribute is neither supported nor constrained by it, and is therefore unintelligible and tautologically excluded from the reality of which it is the hological identity and unique source of coherence and intelligibility.
Prins: The idea that you're draining the swamp when you are specifically filling it with the masters of the swamp, is just tautologically impossible.
The answer, somewhat tautologically, is that the Guidelines only promote uniformity with respect to those facts identified in the Guidelines.
Of course, the correct answer would lie in identifying that travel time is the result of speed and distance, notwithstanding that the three variables are all defined tautologically in terms of each other.
Such an approach is tautologically flawed and doomed to result in a perpetual cycle of violence.
b) Tautologically, by selecting the model complexity using cross-validation to optimize predictive performance, predictive performance of the routine is optimized; thus, the task of making better and more accurate forecasts is reduced to that of finding potentially informative covariates.
PRUDENCIO DengCoy Miel's long-overdue first one-man show, Philippine Barokue, serves up tautologically layered nuances as delicious as a bandejado of fresh talaba.
were more like public property, judges reasoned tautologically, because
A few lines later she writes, tautologically, that, although the events in one tale may differ from those in another, "a highly linear plot structure will still prove a tale to be a linear, coherent narrative" (ibid.
161) By selecting harmful characteristics, Posner tautologically ensures that hiding the characteristic will cause harm.
59) Proceeding to the "effects" analysis, the Court omitted two of the factors, and analyzed others, tautologically, on the basis of the state's intent.