“Doubt is uncomfortable, certainty is ridiculous.”
Voltaire (French Philosopher and Writer. One of the greatest of all French authors, 1694-1778)

“When in doubt, don’t.”
Benjamin Franklin (American Statesman, Scientist, Philosopher, Printer, Writer and Inventor. 1706-1790)

“Doubt is the beginning not the end of wisdom.”
Proverb

“There lives more faith in honest doubt, Believe me, than in half the creeds.”
Lord Alfred Tennyson

“I respect faith, but doubt is what gets you an education.”
Wilson Mizner

“We know accurately only when we know little; with knowledge doubt increases.”
Goethe

“If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.”
Descartes (1596-1650) French Philosopher and Scientist

“Doubt is the father of invention.”
Galileo

“There are two ways to slide easily through life: to believe everything or to doubt everything; both ways save us from thinking.”
Alfred Korzybski

“Believe those who are seeking the truth; doubt those who find it.”
Andre Gide

“It is the tension between creativity and skepticism that has produced the stunning and unexpected findings of science.”
Carl Sagan

“The only limit to our realization of tomorrow will be our doubts of today.”
Franklin Delano Roosevelt

“The beginning of knowledge is the discovery of something we do not understand.”
Frank Herbert

“We are drowning in information but starved for knowledge.”
John Naisbitt

“The beginning of wisdom is found in doubting; by doubting we come to the question, and by seeking we may come upon the truth.”
Pierre Abelard

“Aerodynamically the bumblebee shouldn’t be able to fly, but the bumblebee doesn’t know that so it goes on flying anyway.”
Mary Kay Ash

“If you’re not confused, you’re not paying attention.”
Tom Peters

“The only thing that makes life possible is permanent, intolerable uncertainty; not knowing what comes next.”
Ursula K. LeGuin