Science seems to be at war with itself.... Naive realism leads to physics, and physics, if true, shows naive realism to be false. Therefore naive realism, if true, is false; therefore it is false.

One of the most painful circumstances of recent advances in science is that each one makes us know less than we thought we did

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.

Your writing is never as good as you hoped; but never as bad as you feared.

I know a parson who frightened his congregation terribly by telling them the second coming was very imminent indeed, but they were much consoled when they found he was planting trees in his garden.

While the dogmatist is harmful, the sceptic is useless ...; one is certain of knowing, the other of not knowing. What philosophy should dissipate is certainty, whether of knowledge or of ignorance. Knowledge is not so precise a concept as is commonly thought. Instead of saying 'I know this', we ought to say 'I more or less know something more or less like this'. ... Knowledge in practical affairs has not the certainty or the precision of arithmetic.

I used often to go to America during Prohibition, and there was far more drunkenness there then than before; the prohibition of pornography has much the same effect.