“In all honesty it was easier to believe it in cool Long Island for its very outrageousness where nobody believed anything very seriously than in hot Carolina where everybody was a Christian and found unbelief unbelievable.”

Source: The Dharma Bums

Twelve Virtues Of Rationality http://yudkowsky.net/rational/virtues
Context: Do not flinch from experiences that might destroy your beliefs. The thought you cannot think controls you more than thoughts you speak aloud. Submit yourself to ordeals and test yourself in fire. Relinquish the emotion which rests upon a mistaken belief, and seek to feel fully that emotion which fits the facts. If the iron approaches your face, and you believe it is hot, and it is cool, the Way opposes your fear. If the iron approaches your face, and you believe it is cool, and it is hot, the Way opposes your calm. Evaluate your beliefs first and then arrive at your emotions. Let yourself say: “If the iron is hot, I desire to believe it is hot, and if it is cool, I desire to believe it is cool.”

Source: The Thin Man

Preface
Taken Care Of (1965)

No known source; also attributed to Susan Sarandon.[citation needed]
Disputed

The Ethics of Belief (1877), The Limits Of Inference
Context: p>We may believe what goes beyond our experience, only when it is inferred from that experience by the assumption that what we do not know is like what we know. We may believe the statement of another person, when there is reasonable ground for supposing that he knows the matter of which he speaks, and that he is speaking the truth so far as he knows it.It is wrong in all cases to believe on insufficient evidence; and where it is presumption to doubt and to investigate, there it is worse than presumption to believe.</p

Source: Where the Wild Things Are

The Scent of Water (1963), Chapter 13.2