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

If we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them.

I personally call the type of government which can be removed without violence 'democracy,' and the other, 'tyranny.'.

The metaphysical doctrine of determinism simply asserts that all events in this world are fixed, or unalterable, or predetermined. It does not assert that they are known to anybody, or predictable by scientific means. But it asserts that the future is as little changeable as is the past. Everybody knows what we mean when we say that the past cannot be changed. It is in precisely the same sense that the future cannot be changed, according to metaphysical determinism.

The belief in a political Utopia is especially dangerous. This is possibly connected with the fact that the search for a better world, like the investigation of our environment, is (if I am correct) one of the oldest and most important of all the instincts.

No particular theory may ever be regarded as absolutely certain.... No scientific theory is sacrosanct.

No book can ever be finished. While working on it we learn just enough to find it immature the moment we turn away from it