A curious paradox characteristic of every kind of courage here confronts us. It is the seeming contradiction that we must be fully committed, but we must also be aware at the same time that we might possibly be wrong. This dialectic relationship between conviction and doubt is characteristic of the highest types of courage . . .
People who claim to be absolutely convinced that their stand is the only right one are dangerous. Such conviction is the essence not only of dogmatism, but of its more destructive cousin, fanaticism. It blocks off the user from learning new truth, and it is a dead giveaway of unconscious doubt. The person then has to double his or her protests to quiet not only the opposition but his or her own unconscious doubts as well. . . .
. . . The relationship between commitment and doubt is by no means an antagonistic one. Commitment is healthiest when it is not without doubt, but in spite of doubt. To believe fully and and the same time to have doubts is not at all a contradiction: it presupposes a greater respect for truth, an awareness that truth always goes beyond anything that can be said or done at any given moment. To every thesis there is an antithesis, and to this there is a synthesis. Truth is thus a never-dying process. We then know the meaning of the statement attributed to Leibnitz: "I would walk twenty miles to listen to my worst enemy if I could learn something."
-Rollo May, The Courage To Create