Frege's Puzzle
In the philosophy of language, "Hesperus is Phosphorus" is a famous sentence in relation to the semantics of proper names. Gottlob Frege used the terms "the evening star" (der Abendstern) and "the morning star" (der Morgenstern) to illustrate his distinction between sense and reference, and subsequent philosophers changed the example to "Hesperus is Phosphorus" so that it utilized proper names. Saul Kripke used the sentence to demonstrate that the knowledge of something necessary (in this case the identity of Hesperus and Phosphorus) could be discoverable rather than known a priori. On this question see Frege's Puzzle.
Read more about this topic: Phosphorus (morning Star)
Famous quotes containing the words frege and/or puzzle:
“I hope I may claim in the present work to have made it probable that the laws of arithmetic are analytic judgments and consequently a priori. Arithmetic thus becomes simply a development of logic, and every proposition of arithmetic a law of logic, albeit a derivative one. To apply arithmetic in the physical sciences is to bring logic to bear on observed facts; calculation becomes deduction.”
—Gottlob Frege (1848–1925)
“The at present unutterable things we may find somewhere uttered. These same questions that disturb and puzzle and confound us have in their turn occurred to all the wise men; not one has been omitted; and each has answered them, according to his ability, by his words and his life.”
—Henry David Thoreau (1817–1862)