Carl Sagan Quotes

I’m a skeptic not because I do not want to believe, but because I want to know. How can we tell the difference between what we would like to be true and what is actually true? The answer is science.

Extraordinary claims require extraordinary evidence.

I believe in things that have proof.

...Thomas did not believe the resurrection [John 20:25], and, as they say, would not believe without having ocular and manual demonstration himself. So neither will I, and the reason is equally as good for me, and for every other person, as for Thomas.

The interest I have to believe a thing is no proof that such a thing exists.

More frightening than any particular beliefs or policies is an utter lack of any sense of a need to test those beliefs and policies against hard evidence. Mistakes can be corrected by those who pay attention to facts, but dogmatism will not be corrected by those who are wedded to a vision.

Skeptics question the validity of a particular claim by calling for evidence to prove or disprove it.

Doubt the conventional wisdom unless you can verify it with reason and experiment.

Being a skeptic just means being rational and empirical: thinking and seeing before believing.

We must never assume that which is incapable of proof.

In my opinion, it helps enormously to know why something is true, rather than being told it is true, for why should you believe me? Never believe anything on the authority of a single person but seek confirmation — and reason is the best confirmation

Once you reject evidence as a source of knowledge, you don't gotta believe nothin' you don't like.

Throughout history, every mystery ever solved has turned out to be NOT magic.

I don't believe anything till I have seen the proof. For anything without proof, I think we should believe the theory that gives us peace. It doesn't matter whether the theory is true or not.

The typical person has no trouble believing without knowing. What people need to realize is simply that you do not need to believe to know.

If someone doesn’t value evidence, what evidence are you going to provide that proves they should value evidence. If someone doesn’t value logic, what logical argument would you invoke to prove they should value logic?

No amount of belief makes something a fact.

Now is the time for everyone who believes in the rule of reason to speak up against pathological science and its purveyors.

Faith is the surrender of the mind; it's the surrender of reason, it's the surrender of the only thing that makes us different from other mammals. It's our need to believe, and to surrender our skepticism and our reason, our yearning to discard that and put all our trust or faith in someone or something, that is the sinister thing to me. Of all the supposed virtues, faith must be the most overrated.

Belief is desecrated when given to unproved and unquestioned statements for the solace and private pleasure of the believer . . . It is wrong always, everywhere, and for every one, to believe anything upon insufficient evidence.

Science is a way of thinking that helps you not to fool yourself.

I believe that the extraordinary should be pursued. But extraordinary claims require extraordinary evidence.

The beliefs which we have most warrant for, have no safeguard to rest on, but a standing invitation to the whole world to prove them unfounded.

As a scientist, I don't believe anything. Science shouldn't use the word belief. There are things more likely and less likely. Science can say nothing with absolute certainty.

Exceptional claims, require exceptional evidence.