It will contribute towards one's object, who wishes to acquire a facility in the gaining of knowledge, to doubt judiciously.
- Aristotle
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
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
Man's most valuable trait is a judicious sense of what not to believe.
- Euripides
The uncompromising attitude is more indicative of an inner uncertainty than a deep conviction. The implacable stand is directed more against the doubt within than the assailant without.
- Eric Hoffer
With most people unbelief in one thing is founded upon blind belief in another.
- Georg Christoph Lichtenberg
It is only doubt that creates. It is only the minority that counts.
- H.L. Mencken
For men become civilized, not in proportion to their willingness to believe, but in proportion to their readiness to doubt.
- H.L. Mencken
Doubt is not a pleasant condition, but certainty is absurd.
- Voltaire
'Truth' never set anyone free. It is only doubt which will bring mental emancipation.
- Anton LaVey, quoted by Arthur Lyons, Satan Wants You
William James used to preach the 'will to believe.' For my part, I should wish to preach the 'will to doubt.' What is wanted is not the will to believe but the will to find out, which is the exact opposite.
- Bertrand Russell, Sceptical Essays, 1928
The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt.
- Bertrand Russell
Doubt is the beginning of wisdom.
- Clarence Darrow
When in danger, or in doubt
Run in circles, scream and shout
- Robert A. Heinlein
Doubtless, you want to be my friend. Come back on Tuesday.
- Dorothy Parker
Skepticism
- the philosophical doctrine that absolute knowledge is impossible and that inquiry must be a process of doubting in order to acquire approximate or relative knowledge.
There lives more faith in honest doubt, believe me, than in half the creeds.
- Tennyson
Doubt everything or believe everything; these are two equally convenient strategies. With either we dispense with the need for reflection.
- Henri Poincare
There are two ways to slide easily through life: to believe everything or to doubt everything; both ways save us from thinking.
- Alfred Korzybski
To believe with certainty, we must begin by doubting
- Stanislaus
"... Socrates was executed not for saying what things were or should be, but for seeking practical indications of where some reasonable approximation of truth might be. He was executed not for his megalomania or grandiose propositions or certitudes, but for stubbornly doubting the absolute truths of others."
- John Ralston Saul
I respect faith, but doubt is what gives you an education.
- Wilson Mizner
When in doubt, do it. It's much easier to apologize than to get permission.
- Grace Murray Hopper
When in doubt, tell the truth.
- Mark Twain
Faith which does not doubt is a dead faith
- Unamuno
"The believer is happy; the doubter is wise."
- Hungarian proverb
Doubt is a pain too lonely to know that faith is his twin brother.
- Kahlil Gibran
Beliefs are what divide people. Doubt unites them.
-Peter Ustinov
Habit is the ballast that chains a dog to its vomit
-R. Head
Try as we may, no concept is limited in such a way that there is no room for any doubt. We introduce a concept and limit it in some directions; for instance, we define gold in contrast to some other metals such as alloys. This suffices for our present needs, and we do not probe any farther. We tend to overlook the fact that there are always other directions in which the concept has not been defined. And if we did, we could easily imagine conditions which would necessitate new limitations. In short, it is not possible to define a concept like gold with absolute precision, i.e., in such a way that every nook and cranny is blocked against entry of doubt.
- Friedrich Waismann
We cannot begin with complete doubt. We must begin with all the prejudices which we actually have when we enter upon the study of philosophy. These prejudices are not to be dispelled by a maxim, for they are things which it does not occur to us can be questioned. Hence this initial scepticism will be a mere selfdeception, and not real doubt; and no one who follows the Cartesian method will ever be satisfied until he has formally recovered all those beliefs which in form he has given up. It is, therefore, as useless as a preliminary as going to the North Pole would be in order to get to Constantinople by coming down regularly upon a meridian. A person may, it is true, find reason to doubt what he began by believing; but in that case he doubts because he has a positive reason for it, and not on account of the Cartesian maxim. Let us not pretend to doubt in philosophy what we do not doubt in our hearts.
- C. S. Peirce
The right to search for the truth implies also a duty; one must not conceal any part of what one has recognized to be the truth.
- Albert Einstein
Once upon a time there was a magnet, and in its close neighborhood lived some steel filings. One day two or three filings felt a sudden desire to go and visit the magnet, and they began to talk of what a pleasant thing it would be to do. Other filings nearby overheard their conversation, and they, too, became infected with the same desire. Still others joined them, till at last all the filings began to discuss the matter, and more and more their vague desire grew into an impulse. "Why not go today?" said some of them; but others were of the opinion that it would be better to wait until tomorrow. Meanwhile, without their having noticed it, they had been involuntarily moving nearer to the magnet, which lay there quite still, apparently taking no heed of them. And so they went on discussing, all the time insensibly drawing nearer to their neighbor; and the more they talked, the more they felt the impulse growing stronger, till the more impatient ones declared that they would go that day, whatever the rest did. Some were heard to say that it was their duty to visit the magnet, and that they ought to have gone long ago. And, while they talked, they moved always nearer and nearer, without realizing they had moved. Then, at last, the impatient ones prevailed, and, with one irresistible impulse, the whole body cried out, "There is no use waiting. We will go today. We will go now. We will go at once." And then in one unanimous mass they swept along, and in another moment were clinging fast to the magnet on every side. Then the magnet smiled—for the steel filings had no doubt at all but that they were paying that visit on their own free will.
- Oscar Wilde
When, however, we speak of philosophy as a criticism of knowledge, it is necessary to impose a certain limitation. If we adopt the attitude of the complete sceptic, placing ourselves wholly outside all knowledge, and asking, from this outside position, to be compelled to return within the circle of knowledge, we are demanding what is impossible, and our scepticism can never be refuted. For all refutation must begin with some piece of knowledge which the disputants share; from blank doubt, no argument can begin.
- Bertrand Russell