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:
“Ah, Marilyn, Hollywood’s Joan of Arc, our Ultimate Sacrificial Lamb. Well, let me tell you, she was mean, terribly mean. The meanest woman I have ever known in this town. I am appalled by this Marilyn Monroe cult. Perhaps it’s getting to be an act of courage to say the truth about her. Well, let me be courageous. I have never met anyone as utterly mean as Marilyn Monroe. Nor as utterly fabulous on the screen, and that includes Garbo.”
—Billy Wilder (b. 1906)
“The values by which we are to survive are not rules for just and unjust conduct, but are those deeper illuminations in whose light justice and injustice, good and evil, means and ends are seen in fearful sharpness of outline.”
—Jacob Bronowski (1908–1974)
“Propositions show what they say: tautologies and contradictions show that they say nothing.”
—Ludwig Wittgenstein (1889–1951)