Doubt is the father of invention.

Galileo Galilei

It is only about things that do not interest one that one can give really unbiased opinions, which is no doubt the reason why an unbiased opinion is always valueless.

Oscar Wilde

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.

Rene Descartes

Our doubts are traitors, And make us lose the good we oft might win By fearing to attempt.

William Shakespeare

He who knows nothing, doubts nothing.

Spanish Proverb

I show you doubt, to prove that faith exists.

Robert Browning

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

Johann Wolfgang von Goethe

To believe with certainty we must begin with doubting.

Stanislaw Leszczynski

You should never doubt what no one is sure about.

Willy Wonka

Beliefs are what divide people. Doubt unites them.

Peter Ustinov

Doubt whom you will, but never yourself.

Christine Bovee

Doubt is the vestibule through which all must pass before they can enter into the temple of wisdom.

Charles Caleb Colton

A reasonable doubt is nothing more than a doubt for which reasons can be given. The fact that 1 or 2 men out of 12 differ from the others does not establish that their doubts are reasonable.

Lord Hailsham

Doubt 'til thou canst doubt no more...doubt is thought and thought is life. Systems which end doubt are devices for drugging thought.

Albert Guerard

Doubt is not below knowledge but above it.

Alain Rene Lesage

Doubt is not the opposite of faith; it is one element of faith.

Paul Tillich

Just think of the tragedy of teaching children not to doubt.

Clarence Darrow

Finish each day and be done with it. You have done what you could. Some blunders and absurdities no doubt crept in; forget them as soon as you can. Tomorrow is a new day; begin it well and serenely and with too high a spirit to be encumbered with your old nonsense.

Ralph Waldo Emerson

When we are not sure, we are alive.

Graham Greene

Doubt is the beginning, not the end, of wisdom.

George Iles

True science teaches, above all, to doubt and to be ignorant.

Miguel de Unamuno

I doubt whether the world holds for any one a more soul-stirring surprise than the first adventure with ice cream.

Heywood C. Broun

When in doubt, have a man come through the door with a gun in his hand.

Raymond Chandler

To have doubted one's own first principles is the mark of a civilized man.

Oliver Wendell Holmes Jr.

There is no doubt that someone who tries to throw a curve or pitch at any early age before he's developed, before his hand is big enough to grip the ball correctly, will damage his arm.

Robin Roberts

Doubt cannot override a certainty.

The Talmud

Doubt is to certainty as neurosis is to psychosis. The neurotic is in doubt and has fears about persons and things; the psychotic has convictions and makes claims about them. In short, the neurotic has problems, the psychotic has solutions.

Thomas S. Szasz

No doubt alcohol, tobacco, and so forth, are things that a saint must avoid, but sainthood is a thing that human beings must avoid.

George Orwell