Carl Sagan

Books, purchasable at low cost, permit us to interrogate the past with high accuracy; to tap the wisdom of our species; to understand the point of view of others, and not just those in power; to contemplate — with the best teachers — the insights, painfully extracted from Nature, of the greatest minds that ever were, drawn from the entire planet and from all of our history. They allow people long dead to talk inside our heads. Books can accompany us everywhere. Books are patient where we are slow to understand, allow us to go over the hard parts as many times as we wish, and are never critical of our lapses. Books are key to understanding the world and participating in a democratic society.

That kind of skeptical, questioning, "don't accept what authority tells you" attitude of science — is also nearly identical to the attitude of mind necessary for a functioning democracy. Science and democracy have very consonant values and approaches, and I don't think you can have one without the other.

“Do you understand what’s going on?”
“Not at all,” he shouted back. “I can almost prove this can’t be happening.”

What counts is not what sounds plausible, not what we would like to believe, not what one or two witnesses claim, but only what is supported by hard evidence rigorously and skeptically examined. Extraordinary claims require extraordinary evidence.

For all I know we may be visited by a different extraterrestrial civilization every second Tuesday, but there's no support for this appealing idea. The extraordinary claims are not supported by extraordinary evidence.

Those who are skeptical about carbon dioxide greenhouse warming might profitably note the massive greenhouse effect on Venus. No one proposes that Venus's greenhouse effect derives from imprudent Venusians who burned too much coal, drove fuel-inefficient autos, and cut down their forests. My point is different. The climatological history of our planetary neighbor, an otherwise Earthlike planet on which the surface became hot enough to melt tin or lead, is worth considering — especially by those who say that the increasing greenhouse effect on Earth will be self-correcting, that we don't really have to worry about it, or (you can see this in the publications of some groups that call themselves conservative) that the greenhouse effect is a "hoax".

You can’t convince a believer of anything; for their belief is not based on evidence, it’s based on a deep seated need to believe. [This is from Dr. Arroway in Carl Sagan's Contact (New York: Pocket Books, 1985]

If we long to believe that the stars rise and set for us, that we are the reason there is a Universe, does science do us a disservice in deflating our conceits?

The old man made himself look hard at the Raven and saw that it was not a great bird from the sky but the work of men like himself. This first encounter turned out to be peaceful. The men of the La Pérouse expedition were under strict orders to treat with respect any people they might discover, an exceptional policy for its time and after.

The chiliasts made an atheist out of me.

It is all a matter of time scale. An event that would be unthinkable in a hundred years may be inevitable in a hundred million.

If you take a look at science in its everyday function, of course you find that scientists run the gamut of human emotions and personalities and character and so on. But there’s one thing that is really striking to the outsider, and that is the gauntlet of criticism that is considered acceptable or even desirable. The poor graduate student at his or her Ph.D. oral exam is subjected to a withering crossfire of questions that sometimes seem hostile or contemptuous; this from the professors who have the candidate’s future in their grasp. The students naturally are nervous; who wouldn’t be? True, they’ve prepared for it for years. But they understand that at that critical moment they really have to be able to answer questions. So in preparing to defend their theses, they must anticipate questions; they have to think, “Where in my thesis is there a weakness that someone else might find — because I sure better find it before they do, because if they find it and I'm not prepared, I'm in deep trouble."

The choice is with us still, but the civilization now in jeopardy is all humanity. As the ancient myth makers knew, we are children equally of the earth and the sky. In our tenure on this planet we've accumulated dangerous evolutionary baggage — propensities for aggression and ritual, submission to leaders, hostility to outsiders — all of which puts our survival in some doubt. But we've also acquired compassion for others, love for our children and desire to learn from history and experience, and a great soaring passionate intelligence — the clear tools for our continued survival and prosperity. Which aspects of our nature will prevail is uncertain, particularly when our visions and prospects are bound to one small part of the small planet Earth. But up there in the immensity of the Cosmos, an inescapable perspective awaits us. There are not yet any obvious signs of extraterrestrial intelligence and this makes us wonder whether civilizations like ours always rush implacably, headlong, toward self-destruction. National boundaries are not evident when we view the Earth from space. Fanatical ethnic or religious or national chauvinisms are a little difficult to maintain when we see our planet as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and citadel of the stars. Travel is broadening.

As a boy Kepler had been captured by a vision of cosmic splendour, a harmony of the worlds which he sought so tirelessly all his life. Harmony in this world eluded him. His three laws of planetary motion represent, we now know, a real harmony of the worlds, but to Kepler they were only incidental to his quest for a cosmic system based on the Perfect Solids, a system which, it turns out, existed only in his mind. Yet from his work, we have found that scientific laws pervade all of nature, that the same rules apply on Earth as in the skies, that we can find a resonance, a harmony, between the way we think and the way the world works.
When he found that his long cherished beliefs did not agree with the most precise observations, he accepted the uncomfortable facts, he preferred the hard truth to his dearest illusions. That is the heart of science.

In some respects, science has far surpassed religion in delivering awe. How is it that hardly any major religion has looked at science and concluded, "This is better than we thought! The Universe is much bigger than our prophets said, grander, more subtle, more elegant. God must be even greater than we dreamed"? Instead they say, "No, no, no! My god is a little god, and I want him to stay that way."

Imagination will often carry us to worlds that never were. But without it we go nowhere.

Every thinking person fears nuclear war and every technological nation plans for it. Everyone knows it's madness, and every country has an excuse.

Instead of wanting everyone to share and know of their discoveries the Pythagoreans suppressed the square root of two and the dodecahedron. The outside world was not to know. The Pythagoreans had discovered, in the mathematical underpinnings of nature, one of the two most powerful scientific tools, the other of course is experiment, but instead of using their insight to advance the collective voyage of human discovery they made of it little more than the hocus-pocus of a mystery cult. Science and mathematics were to be removed from the hands of the merchants and the artisans.

But we don't yet know whether the Universe is open or closed. More than that, there are a few astronomers who doubt that the redshift of distant galaxies is due to the doppler effect, who are skeptical of the expanding Universe and the Big Bang. Perhaps our descendants will regard our present ignorance with as much sympathy as we feel to the ancients for not knowing the Earth went around the Sun. If the general picture, however, of a Big Bang followed by an expanding Universe is correct, what happened before that? Was the Universe devoid of all matter and then the matter suddenly somehow created, how did that happen? In many cultures, the customary answer is that a God or Gods created the Universe out of nothing. But if we wish to pursue this question courageously, we must of course ask the next question: where did God come from? If we decide that this is an unanswerable question, why not save a step and conclude that the origin of the Universe is an unanswerable question? Or, if we say that God always existed, why not save a step, and conclude that the Universe always existed? That there's no need for a creation, it was always here. These are not easy questions. Cosmology brings us face to face with the deepest mysteries, questions that were once treated only in religion and myth.

Unlike the La Pérouse expedition the Conquistadors sought not knowledge but Gold. They used their superior weapons to loot and murder, in their madness they obliterated a civilisation. In the name of piety, in a mockery of their religion, the Spaniards utterly destroyed a society with an Art, Astronomy and Architecture the equal of anything in Europe. We revile the Conquistadors for their cruelty and shortsightedness, for choosing death. We admire La Pérouse and the Tlingit for their courage and wisdom, for choosing life. The choice is with us still, but the civilisation now in jeopardy is all humanity. As the ancient myth makers knew we're children equally of the earth and the sky. In our tenure on this planet we've accumulated dangerous evolutionary baggage, propensities for aggression and ritual, submission to leaders, hostility to outsiders, all of which puts our survival in some doubt. But we've also acquired compassion for others, love for our children, a desire to learn from history and experience and a great soaring passionate intelligence, the clear tools for our continued survival and prosperity. Which aspects of our nature will prevail is uncertain, particularly when our visions and prospects are bound to one small part of the small planet Earth. But up there in the Cosmos an inescapable perspective awaits. National boundaries are not evident when we view the Earth from space. Fanatical ethnic or religious or national identifications are a little difficult to support when we see our Earth as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and the citadel of the stars. There are not yet obvious signs of extraterrestrial intelligence and this makes us wonder whether civilisations like ours rush inevitably headlong into self-destruction.