The attempt to make heaven on earth invariably produces hell.

You cannot have a rational discussion with a man who prefers shooting you to being convinced by you.

It is wrong to ask who will rule. The ability to vote a bad government out of office is enough. That is democracy.

Serious rational criticism is so rare that it should be encouraged. Being too ready to defend oneself is more dangerous than being too ready to admit a mistake.

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 growth of knowledge depends entirely upon disagreement.

Contrary to the outstanding work of art, outstanding theory is susceptible to improvements.