The defence of democracy must consist in making anti-democratic experiences too costly for those who try them; much more costly than a democratic compromise

The survival value of intelligence is that it allows us to extinct a bad idea, before the idea extincts us.

A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.

We have become makers of our fate when we have ceased to pose as its prophets.

The genuine rationalist does not think that he or anyone else is in possession of the truth; nor does he think that mere criticism as such helps us achieve new ideas. But he does think that, in the sphere of ideas, only critical discussion can help us sort the wheat from the chaff.

Evolution is not a fact. Evolution doesn't even qualify as a theory or as a hypothesis. It is a metaphysical research program, and it is not really testable science.

The defence of democracy must consist in making anti-democratic experiences too costly for those who try them; much more costly than a democratic compromise