David Schwartz

“Don't you believe in flying saucers, they ask me? Don't you believe in telepathy? — in ancient astronauts? — in the Bermuda triangle? — in life after death?
No, I reply. No, no, no, no, and again no.
One person recently, goaded into desperation by the litany of unrelieved negation, burst out "Don't you believe in anything?"
Yes", I said. "I believe in evidence. I believe in observation, measurement, and reasoning, confirmed by independent observers. I'll believe anything, no matter how wild and ridiculous, if there is evidence for it. The wilder and more ridiculous something is, however, the firmer and more solid the evidence will have to be.”
― Isaac Asimov

“Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence.”
― John Adams, The Portable John Adams

“The thing is, it's very dangerous to have a fixed idea. A person with a fixed idea will always find some way of convincing himself in the end that he is right”
― Atle Selberg

“...and when is enough proof enough?”
― Jonathan Safran Foer, Everything is Illuminated