Truth Values and Tautologies
Considering different interpretations of the same statement leads to the notion of truth value. Simplest approach to truth values means that the statement may be "true" in one case, but "false" in another. In one sense of the term "tautology", it is any type of formula or proposition which turns out to be true under any possible interpretation of its terms (may also be called a valuation or assignment depending upon the context). This is synonymous to logical truth.
However, the term "tautology" is also commonly used to refer to what could more specifically called truth-functional tautologies. Whereas a tautology or logical truth is true solely because of the logical terms it contains in general (e.g. "every", "some", and "is"), a truth-functional tautology is true because of the logical terms it contains which are logical connectives (e.g. "or", "and", and "nor"). Not all logical truths are tautologies of such kind.
Read more about this topic: Logical Truth
Famous quotes containing the words truth, values and/or tautologies:
“To regard the successful experiences which ensue from a belief as a criterion of its truth is one thing—and a thing that is sometimes bad and sometimes good—but to assume that truth itself consists in the process by which it is verified is a different thing and always bad.”
—William Pepperell Montague (1842–1910)
“Tallulah [Bankhead] was the foremost naughty girl of her era but, in those days, “naughty” meant piquant, whereas values have so changed that now, in the 1970s, it generally means nauseating.”
—Anita Loos (1888–1981)
“Propositions show what they say: tautologies and contradictions show that they say nothing.”
—Ludwig Wittgenstein (1889–1951)