Whenever a man acts purposively, he acts under a belief in some experimental phenomenon. Consequently, the sum of the experimental phenomena that a proposition implies makes up its entire bearing upon human conduct.
Charles Sanders PeirceThe one [the logician] studies the science of drawing conclusions, the other [the mathematician] the science which draws necessary conclusions.
Charles Sanders PeirceMathematics is purely hypothetical: it produces nothing but conditional propositions.
Charles Sanders PeirceFor example, there are numbers of chemists who occupy themselves exclusively with the study of dyestuffs. They discover facts that are useful to scientific chemistry; but they do not rank as genuine scientific men. The genuine scientific chemist cares just as much to learn about erbium-the extreme rarity of which renders it commercially unimportant-as he does about iron. He is more eager to learn about erbium if the knowledge of it would do more to complete his conception of the Periodic Law, which expresses the mutual relations of the elements.
Charles Sanders PeirceIt is the man of science, eager to have his every opinion regenerated, his every idea rationalized, by drinking at the fountain of fact, and devoting all the energies of his life to the cult of truth, not as he understands it, but as he does not yet understand it, that ought properly to be called a philosopher.
Charles Sanders Peirce