"The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. "
— Bertrand Russell

"Extraordinary claims require extraordinary evidence."
— Carl Sagan

"The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what's true."
— Carl Sagan

"Those who can make you believe absurdities can make you commit atrocities."
— Voltaire

"I do not agree with a word you say but will defend to the death your right to say it."
— Evelyn Beatrice Hall

"Who is more humble? The scientist who looks at the universe with an open mind and accepts whatever the universe has to teach us, or somebody who says everything in this book must be considered the literal truth and never mind the fallibility of all the human beings involved?"
— Carl Sagan

"Give to every other human being every right that you claim for yourself - that is my doctrine."
— Thomas Paine (The Age of Reason)

"Every aspect of Nature reveals a deep mystery and touches our sense of wonder and awe. Those afraid of the universe as it really is, those who pretend to nonexistent knowledge and envision a Cosmos centered on human beings will prefer the fleeting comforts of superstition. They avoid rather than confront the world. But those with the courage to explore the weave and structure of the Cosmos, even where it differs profoundly from their wishes and prejudices, will penetrate its deepest mysteries."
— Carl Sagan

"Most institutions demand unqualified faith; but the institution of science makes skepticism a virtue."
— Robert King Merton (Social Theory and Social Structure)

"One good schoolmaster is of more use than a hundred priests."
— Thomas Paine (The Age of Reason)

"Men are never convinced of your reasons, of your sincerity, of the seriousness of your sufferings, except by your death. So long as you are alive, your case is doubtful; you have a right only to their skepticism."
— Albert Camus (The Fall)

"Observation: I can't see a thing. Conclusion: Dinosaurs."
— Carl Sagan (Cosmos)

"I have always strenuously supported the right of every man to his own opinion, however different that opinion might be to mine. He who denies to another this right, makes a slave of himself to his present opinion, because he precludes himself the right of changing it."
— Thomas Paine (The Age of Reason)

"It is my firm conviction that man has nothing to gain, emotionally or otherwise, by adhering to a falsehood, regardless of how comfortable or sacred that falsehood may appear. Anyone who claims, on the one hand, that he is concerned with human welfare, and who demands, on the other hand, that man must suspend or renounce the use of his reason, is contradicting himself.

There can be no knowledge of what is good for man apart from knowledge of reality and human nature, and there is no manner in which this knowledge can be acquired except through reason. To advocate irrationality is to advocate that which is destructive to human life."
— George H. Smith (Atheism: The Case Against God)

"I am satisfied, and sufficiently occupied with the things which are, without tormenting or troubling myself about those which may indeed be, but of which I have no evidence."
— Thomas Jefferson

"Men think epilepsy divine, merely because they do not understand it. But if they called everything divine which they do not understand, why, there would be no end to divine things."
— Hippocrates

"As every inquiry which regards religion is of the utmost importance, there are two questions in particular which challenge our attention, to wit, that concerning its foundation in reason, and that concerning it origin in human nature."
— David Hume (The Natural History of Religion)

"If you are searching for sacred knowledge and not just a palliative for your fears, then you will train yourself to be a good skeptic."
— Ann Druyan

"Religious moderation is the product of secular knowledge and scriptural ignorance."
— Sam Harris (The End of Faith: Religion, Terror, and the Future of Reason)

"I can indeed hardly see how anyone ought to wish Christianity to be true for if so the plain language of the text seems to show that the men who do not believe and this would include my Father Brother and almost all of my friends will be everlastingly punished. And this is a damnable doctrine."
— Charles Darwin

"Persecution is not an original feature in any religion; but it is always the strongly marked feature of all religions established by law."
— Thomas Paine (The Age of Reason)

"Present global culture is a kind of arrogant newcomer. It arrives on the planetary stage following four and a half billion years of other acts, and after looking about for a few thousand years declares itself in possession of eternal truths. But in a world that is changing as fast as ours, this is a prescription for disaster. No nation, no religion, no economic system, no body of knowledge, is likely to have all the answers for our survival. There must be many social systems that would work far better than any now in existence. In the scientific tradition, our task is to find them."
— Carl Sagan

"You could just as well say that an agnostic is a deeply religious person with at least a rudimentary knowledge of human fallibility."
— Carl Sagan

"Is it more probable that nature should go out of her course or that a man should tell a lie? We have never seen, in our time, nature go out of her course. But we have good reason to believe that millions of lies have been told in the same time. It is therefore at least millions to one that the reporter of a miracle tells a lie. "
— Thomas Paine (The Age of Reason)

"Give me the storm and tempest of thought and action, rather than the dead calm of ignorance and faith. Banish me from Eden when you will; but first let me eat of the fruit of the tree of knowledge."
— Robert G. Ingersoll

"Progress is born of doubt and inquiry. The Church never doubts, never inquires. To doubt is heresy, to inquire is to admit that you do not know—the Church does neither. "
— Robert G. Ingersoll

"Holy Writ was intended to teach men how to go to Heaven not how the heavens go."
— Galileo Galelei

"What we call rational grounds for our beliefs are often extremely irrational attempts to justify our instincts."
— Thomas Henry Huxley

"All the tales of miracles, with which the Old and New Testament are filled, are fit only for impostors to preach and fools to believe."
— Thomas Paine (The Age of Reason)

"I wanted to cast doubt on the step he was about to take, to help him see there are other ways to live, other ways to seek knowledge, love...even self-transformation. I wanted to convince him his dignity depended on maintaining a free, skeptical attitude towards doctrine. I wanted...to save him...
Doubt, like faith, has to be learned. It is a skill. But the curious thing about skepticism is that its adherents, ancient and modern, have so often been proselytizers. In reading them, I've often wanted to ask: "Why do you care?" Their skepticism offers no good answer to that question."
— Mark Lilla

"It's natural to think that living things must be the handiwork of a designer. But it was also natural to think that the sun went around the earth. Overcoming naive impressions to figure out how things really work is one of humanity's highest callings."
— Steven Pinker

"Reality provides us with facts so romantic that imagination itself could add nothing to them."
— Jules Verne

"Science has carried us to the gateway to the universe. And yet our conception of our surroundings remains the disproportionate view of the still-small child. We are spiritually and culturally paralyzed, unable to face the vastness, to embrace our lack of centrality and find our actual place in the fabric of nature. We batter this planet as if we had someplace else to go. That we even do science is a hopeful glimmer of mental health. However, it's not enough merely to accept these insights intellectually while we cling to a spiritual ideology that is not only rootless in nature but also, in many ways, contemptuous of what is natural."
— Ann Druyan

"Superstition [is] cowardice in the face of the Divine."
— Theophrastus

"The glory of science is, that it is freeing the soul, breaking the mental manacles, getting the brain out of bondage, giving courage to thought, filling the world with mercy, justice, and joy."
— Robert G. Ingersoll

"[Sire,] je n'ai pas eu besoin de cette hypothèse."
En répondant Napoléon qui lui demanda pourquoi sa théorie de l'univers ne indique pas Dieux."
— Pierre-Simon Laplace

"La pensée ne doit jamais se soumettre, ni à un dogme, ni à un parti, ni à une passion, ni à un intérêt, ni à une idée préconçue, ni à quoi que ce soit, si ce n'est aux faits eux-mêmes, parce que, pour elle, se soumettre, ce serait cesser d'être."
— Jules Henri Poincaré (1854 – 1912)

"It would be better for us to have some doubts in an honest pursuit of truth, than it would be for us to be certain about something that was not true. "
— Daniel Wallace

"I have examined all the known superstitions of the world, and I do not find in our particular superstition of Christianity one redeeming feature. They are all alike founded on fables and mythology. Millions of innocent men, women and children, since the introduction of Christianity, have been burnt, tortured, fined and imprisoned. What has been the effect of this coercion? To make one half the world fools and the other half hypocrites; to support roguery and error all over the earth."
— Thomas Jefferson

"The Bible, although dictated by the Holy Spirit, admits...in many passages of an interpretation other than the literal one. And, moreover, we cannot maintain with certainty that all interpreters are inspired by God. Therefore, I think it would be the part of wisdom not to allow any one to apply passages of Scripture in such a way as to force them to support as true any conclusions concerning nature, the contrary of which may afterwards be revealed by the evidence of our senses, or by actual demonstration....I am inclined to think that Holy Scripture is intended to convince people of those truths which are necessary for their salvation, and which being far above human understanding cannot be made credible by any learning, or by any other means than revelation. This, therefore, being granted, I think that in discussing natural phenomena we ought not to begin with texts from Scripture, but with experiment and demonstration."
— Galileo Galelei

"The limit of man s knowledge in any subject possesses a high interest which is perhaps increased by its close neighbourhood to the realms of imagination."
— Charles Darwin

"Being a scientist and staring immensity and eternity in the face everyday is about as meaningful and grand and awe-inspiring as it gets. We, especially we astronomers, confront the big questions of wonder everyday and the answers to these questions in the aggregate have produced, and this is with absolutely no hype, the greatest story that's ever been told, and there isn't a religion, that can offer anything better."
— Carolyn Porco

"When anyone tells me that he saw a dead man restored to life, I immediately consider with myself whether it be more probable that this person should either deceive or be deceived or that the fact which he relates should really have happened. I weigh the one miracle against the other and according to the superiority which I discover, I pronounce my decision. Always I reject the greater miracle. If the falsehood of his testimony would be more miraculous than the event which he relates, then and not till then, can he pretend to command my belief or opinion."
— David Hume

"Are you really surprised by the endurance of religion? What ideology is likely to be more durable than one that conforms, at every turn, to our powers of wishful thinking? Hope is easy; knowledge is hard. Science is the one domain in which we human beings make a truly heroic effort to counter our innate biases and wishful thinking. Science is the one endeavor in which we have developed a refined methodology for separating what a person hopes is true from what he has good reason to believe. The methodology isn't perfect, and the history of science is riddled with abject failures of scientific objectivity. But that is just the point-these have been failures of science, discovered and corrected by-what, religion? No, by good science."
— Sam Harris

"No one, in the world's whole history, ever attempted to substantiate a truth by a miracle. Truth scorns the assistance of miracle. Nothing but falsehood ever attested itself by signs and wonders. No miracle ever was performed, and no sane man ever thought he had performed one, and until one is performed, there can be no evidence of the existence of any power superior to, and independent of nature."
— Robert G. Ingersoll

"In all ages the people have honored those who dishonored them. They have worshiped their destroyers; they have canonized the most gigantic liars, and buried the great thieves in marble and gold. Under the loftiest monuments sleeps the dust of murder."
— Robert G. Ingersoll

"Not one of the orthodox ministers dare preach what he thinks if he knows a majority of his congregation think otherwise. He knows that every member of his church stands guard over his brain with a creed, like a club, in his hand. He knows that he is not expected to search after the truth, but that he is employed to defend the creed. Every pulpit is a pillory, in which stands a hired culprit, defending the justice of his own imprisonment."
— Robert G. Ingersoll