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

There are two ways to slide easily through life; to believe everything or to doubt everything. Both ways save us from thinking.

Alfred Korzybski (1879 - 1950)

A mind troubled by doubt cannot focus on the course to victory.

Arthur Golden, Memoirs¹ of a Geisha

I think we ought always to entertain our opinions with some measure of doubt. I shouldn't wish people dogmatically to believe any philosophy, not even mine.

Bertrand Russell (1872 - 1970)

The whole problem with the world is that fools and fanatics² are always so certain of themselves, but wiser people so full of doubts.

Bertrand Russell (1872 - 1970)

Doubt whom you will, but never yourself.

Christine Bovee

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

Clarence Darrow (1857 - 1938)

To have doubted one's own first principles is the mark of a civilized³ man.

Oliver Wendell Holmes Jr. (1841 - 1935)

Beliefs are what divide people. Doubt unites them.

Peter Ustinov (1921 - 2004)

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 (1596 - 1650)

I show you doubt, to prove that faith exists.

Robert Browning (1812 - 1889)

To believe with certainty⁴ we must begin with doubting.

Stanislaw Leszczynski (1677 - 1766)

Doubt is not a pleasant condition, but certainty is absurd⁵.

Voltaire (1694 - 1778)

Our doubts are traitors⁶,

And make us lose the good we oft might win

By fearing to attempt.

William Shakespeare (1564 - 1616), "Measure for Measure", Act 1 scene 4

I respect faith, but doubt is what gets you an education.

Wilson Mizner (1876 - 1933)