The three main medieval points of view regarding universals are designated by historians as realism, conceptualism, and nominalism. Essentially these same three doctrines reappear in twentieth-century surveys of the philosophy of mathematics under the new names logicism, intuitionism, and formalism.
Willard Van Orman QuineThe mastery of one's phonemes may be compared to the violinist's mastery of fingering. The violin string lends itself to a continuous gradation of tones, but the musician learns the discrete intervals at which to stop the string in order to play the conventional notes. We sound our phonemes like poor violinists, approximating each time to a fancied norm, and we receive our neighbor's renderings indulgently, mentally rectifying the more glaring inaccuracies.
Willard Van Orman QuineThe scientist is indistinguishable from the common man in his sense of evidence, except that the scientist is more careful.
Willard Van Orman QuineFor me the problem of induction is a problem about the world: a problem of how we, as we are now (by our present scientific lights), in a world we never made, should stand better than random, or coin-tossing chances changes of coming out right when we predict by inductions. . . .
Willard Van Orman Quine