It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong - Richard Feynman

The general root of superstition is that men observe when things hit, and not when they miss, and commit to memory the one, and pass over the other. - Sir Francis Bacon

No matter how many times a theory meets its tests successfully, there can be no certainty that it will not be overthrown by the next observation. This, then, is a cornerstone of modern natural philosophy. It makes no claim of attaining ultimate truth. In fact, the phrase "ultimate truth" becomes meaningless, because there is no way in which enough observations can be made to make truth certain and, therefore, "ultimate". - Isaac Asimov

I don't doubt the sincerity of dowsers, but even after we've demonstrated that they can't produce results that are any better than chance they'll still go away believing in their abilities… It is like the mother whose son is caught shoplifting on tape. She wonders why someone would want to frame her child by producing a fake video. - James Randi

During many ages there were witches. The Bible said so. The Bible commanded that they should not be allowed to live. Therefore the Church … imprisoned, tortured, hanged, and burned whole hordes and armies of witches, and washed the Christian world clean with their foul blood. Then it was discovered that there was no such thing as witches, and never had been. One does not know whether to laugh or to cry. - Mark Twain

Aristotle maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives' mouths. - Bertrand Russell

A casual stroll through the lunatic asylum shows that faith does not prove anything. - Friedrich Nietzsche

This is not about proof. Science does not use proof. We favor evidence, and the work consists largely of the slow accumulation of evidence in support of ideas, not magically potent proofs that establish an idea as unassailable. - PZ Myers

Thanks to Bill Garthright's "That's Interesting" Blog