He who decides one day that scientific statements do not call for any further test and that they can be regarded as finally verified retires from the game.
The method of learning by trial and error – of learning from our mistakes – seems to be fundamentally the same whether it is practiced by lower or by higher animals, by chimpanzees, or by men of science.
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.
And it implies that if we respect truth, we must search for it by persistently searching for our errors: by indefatigable rational criticism, and self-criticism.
