“The best lack all conviction; while the worst are filled with passionate intensity.” ~ Yeats in his poem, “The Second Coming.”
Yeats is right. The best people are often filled with doubts; they realize that even those decisions which are made on the basis of the best possible information can turn out to be disastrously wrong. But the scoundrels, buffoons, and the tyrants have total certainty; they are convinced that they, and only they, possess the ultimate truth.
I am not saying that conviction and intensity are bad traits. The best too can be full of conviction and intensity but they are not dogmatic and authoritarian. They do not believe that only they have the ultimate truth and everyone else is always wrong.