The war of ideas is a Greek invention. It is one of the most important inventions ever made. Indeed, the possibility of fighting with with words and ideas instead of fighting with swords is the very basis of our civilization, and especially of all its legal and parliamentary institutions.

We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.

While differing widely in the various little bits we know, in our infinite ignorance we are all equal.

True ignorance is not the absence of knowledge, but the refusal to acquire it.

I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme.

The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance

Philosophers should consider the fact that the greatest happiness principle can easily be made an excuse for a benevolent dictatorship. We should replace it by a more modest and more realistic principle - the principle that the fight against avoidable misery should be a recognized aim of public policy, while the increase of happiness should be left, in the main, to private initiative.