What Galileo and Newton were to the seventeenth century, Darwin was to the nineteenth.

Philosophy is an unusually ingenious attempt to think fallaciously.

Moreover, the attitude that one ought to believe such and such a proposition, independently of the question whether there is evidence in its favor, is an attitude which produces hostility to evidence and causes us to close our minds to every fact that does not suit our prejudices.

You may reasonably expect a man to walk a tightrope safely for ten minutes; it would be unreasonable to do so without accident for two hundred years.

If you think your belief is based upon reason, you will support it by argument rather than by persecution, and will abandon it if the argument goes against you. But if your belief is based upon faith, you will realize that argument is useless, and will therefore resort to force either in the form of persecution or by stunting or distorting the minds of the young in what is called 'education.'

Cruel men believe in a cruel god and use their belief to excuse their cruelty. Only kindly men believe in a kindly god, and they would be kindly in any case.

Scientific method, although in its more refined forms it may seem complicated, is in essence remarkably simply. It consists in observing such facts as will enable the observer to discover general laws governing facts of the kind in question. The two stages, first of observation, and second of inference to a law, are both essential, and each is susceptible of almost indefinite refinement. (1931)