Science is not a substitute for common sense, but an extension of it.

One man's antinomy is another man's falsidical paradox, give or take a couple of thousand years.

Physical objects are conceptually imported into the situation as convenient intermediaries not by definition in terms of experience, but simply as irreducible posits comparable, epistemologically, to the gods of Homer . . . For my part I do, qua lay physicist, believe in physical objects and not in Homer's gods; and I consider it a scientific error to believe otherwise. But in point of epistemological footing, the physical objects and the gods differ only in degree and not in kind. Both sorts of entities enter our conceptions only as cultural posits.

Logic chases truth up the tree of grammar.

Our acceptance of an ontology is, I think, similar in principle to our acceptance of a scientific theory, say a system of physics;we adopt, at least insofar as we are reasonable, the simplest conceptual scheme into which the disordered fragments of raw experience can be fitted and arranged.

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.

For 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. . . .