Logical Truths and Analytic Truths
Logical truths, being analytic statements, do not contain any information about any matters of fact. Other than logical truths, there is also a second class of analytic statements, typified by "No bachelor is married." The characteristic of such a statement is that it can be turned into a logical truth by substituting synonyms for synonyms salva veritate. "No bachelor is married." can be turned into "No unmarried man is married." by substituting 'unmarried man' for its synonym 'bachelor.'
In his essay. Two Dogmas of Empiricism, the philosopher W.V.O. Quine called into question the distinction between analytic and synthetic statements. It was this second class of analytic statements that caused him to note that the concept of analyticity itself stands in need of clarification, because it seems to depend on the concept of synonymy, which stands in need of clarification. In his conclusion, Quine rejects that logical truths are necessary truths. Instead he posits that the truth-value of any statement can be changed, including logical truths, given a re-evaluation of the truth-values of every other statement in one's complete theory.
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Famous quotes containing the words logical, truths and/or analytic:
“The sensual and spiritual are linked together by a mysterious bond, sensed by our emotions, though hidden from our eyes. To this double nature of the visible and invisible world—to the profound longing for the latter, coupled with the feeling of the sweet necessity for the former, we owe all sound and logical systems of philosophy, truly based on the immutable principles of our nature, just as from the same source arise the most senseless enthusiasms.”
—Karl Wilhelm Von Humboldt (1767–1835)
“There are no new truths, but only truths that have not been recognized by those who have perceived them without noticing. A truth is something that everybody can be shown to know and to have known, as people say, all along.”
—Mary McCarthy (1912–1989)
““You, that have not lived in thought but deed,
Can have the purity of a natural force,
But I, whose virtues are the definitions
Of the analytic mind, can neither close
The eye of the mind nor keep my tongue from speech.””
—William Butler Yeats (1865–1939)