“We do not really think, we are barely conscious, until we are forced to think, and we are not forced to think unless we are in a state of doubt.”— Charles Sanders Peirce
“The scientific man is not in the least wedded to his conclusions. He is leaning backwards, in the attitude of doubt.”— Charles Sanders Peirce
“What the world wants is a Christian church that has both the courage of its convictions and the courage of its doubts.”— Lyman Abbott
“The beginning of wisdom is found in doubting; by doubting we come to the question, and by seeking we may come upon the truth.”— Peter Abelard
“If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts, he shall end in certainties.”— Francis Bacon
“Argument is conclusive, but it does not remove doubt, so that the mind may rest in the sure knowledge of the truth, unless it finds it by the method of experiment.”— Roger Bacon
“Doubt is the vestibule which all must pass before they can enter into the temple of wisdom.”— Hosea Ballou
“The moment you doubt whether you can fly, you cease for ever to be able to do it.”— James Matthew Barrie