The Puzzle
Consider the following two sentences:
(1) Hesperus is Hesperus.
(2) Hesperus is Phosphorus.
We can begin by noting that each of these sentences is true, and that 'Hesperus' refers to the same object as 'Phosphorus' (the planet Venus). Nonetheless, (1) and (2) seem to differ in what Frege called cognitive value. One way of analyzing this notion is to say that a person could rationally believe (1) while denying (2). The problem, however, is that proper names are often taken to have no meaning beyond their reference (a view often associated with John Stuart Mill). But this seems to imply that if a person knows the meanings of the words in (1) and (2), he cannot rationally believe one and deny the other: (1) and (2) are synonymous.
Read more about this topic: Frege's Puzzle
Famous quotes containing the word puzzle:
“What are you now? If we could touch one another,
if these our separate entities could come to grips,
clenched like a Chinese puzzle . . . yesterday
I stood in a crowded street that was live with people,
and no one spoke a word, and the morning shone.
Everyone silent, moving. . . . Take my hand. Speak to me.”
—Muriel Rukeyser (1913–1980)
“Scholars and artists thrown together are often annoyed at the puzzle of where they differ. Both work from knowledge; but I suspect they differ most importantly in the way their knowledge is come by. Scholars get theirs with conscientious thoroughness along projected lines of logic; poets theirs cavalierly and as it happens in and out of books. They stick to nothing deliberately, but let what will stick to them like burrs where they walk in the fields.”
—Robert Frost (1874–1963)