I mean by intellectual integrity the habit of deciding vexed questions in accordance with the evidence, or of leaving them undecided where the evidence is inconclusive. This virtue, though it is underestimated by almost all adherents of any system of dogma, is to my mind of the very greatest social importance and far more likely to benefit the world than Christianity or any other system of organized beliefs.

All exact science is dominated by the idea of approximation.

Thomas Aquinas states parenthetically, as something entirely obvious, that men are more rational than women. For my part, I see no evidence of this.

There can't be a practical reason for believing something that is not true.

All who are not lunatics are agreed about certain things : That it is better to be alive than dead, better to be adequately fed than starved, better to be free than a slave

Into every tidy scheme for arranging the pattern of human life, it is necessary to inject a certain dose of anarchism.

It seems to us unwise to have insisted on teaching geometry to the younger Dionysius, tyrant of Syracuse, in order to make him a good king, but from Plato's point of view it was essential. He was sufficiently Pythagorean to think that without mathematics no true wisdom is possible.