The idea of Martian canals grabbed the imagination of American astronomer Percival Lowell, scion of the famous Boston Lowell clan, who spun out an elaborate story of a Martian civilization with a central planetary government and the technological wizardry to engineer a massive system of aqueducts. Lowell even used his own Arizona observatory to identify the Martian capital, called Solis Lacus.

There are no canals on Mars. No cities either, and no government. Indeed, no signs of past life whatsoever, as we know today. All of this was an elaborate phantasm of Lowell's fertile mind, yet as late as the 1950s, popular culture was saturated with imagery of Martians as a technologically advanced extraterrestrial race.

The late Carl Sagan used the misbegotten tale of Martian engineers, in his 1985 Gifford Lectures in Natural Theology at the University of Glasgow, as a cautionary tale about the power of belief and yearning to trump science and reason. The Cornell University astrophysicist, Pulitzer Prize-winning author and TV personality was alarmed by the persistence of such magical thinking even into the late 20th century, despite tremendous scientific progress in understanding both human nature and the cosmos. He used the prestigious lecture series (collected here for the first time by his widow and long-time collaborator, Ann Druyan) as an opportunity to challenge the evidence for everything from the Bermuda Triangle to UFOs to angels and deities. But just as important, he used the lectures to spell out his views on the common ground shared by science and spirituality.

Sagan does not deny the existence of God. Nor does he affirm it. As he quips in the lively Q&A section appended to the lectures, "Absence of evidence is not evidence of absence." What Sagan does do is insist on the primacy of scientific method and scientific evidence, and he holds the many and various "proofs" of God's existence up to these scientific standards. Most are found wanting. But Sagan is not harsh in his critiques of religious thought; he is more perplexed by theology's narrow and unimaginative vision.

Why would an all-powerful God work only on a local (and recent) project like the Earth when there is a vast, 15-billion-year-old universe out there, with countless galaxies containing countless stars and the possibility of countless worlds? Why didn't God let us know about quantum mechanics and natural selection and cosmology from the get-go? And why would theologians insist on such a provincial version of the creation and God's imagination?

Sagan is not being flip or heretical, though he is intellectually playful and obviously likes the fray. Sagan took his own spirituality seriously -- indeed, he defined science as "informed worship." The closest he comes to articulating his own view of God is to describe admiringly the philosophies of Spinoza and Einstein, who basically considered God the sum total of all the laws of physics. These laws, he emphasizes again and again, govern not just the Earth and humanity but every solar system and every star and every galaxy. They are not local ordinances.

Central to Sagan's personal search for the existence of God is the question of other life in the universe. For him, the requirements for proof of extraterrestrial intelligence are essentially the same requirements for proof of angels or demigods or a God. Sagan spends much of one lecture on the so-called Drake equation, which is a way of estimating the number of technologically advanced civilizations in the galaxy. The equation incorporates several values, including the rate of star formation, the fraction of stars with planets around them, the fraction likely to have evolved intelligent life and so forth.

The confounding value is L, which stands for the average lifetime of a technologically advanced civilization. If you plug in an optimistic value, assuming such civilizations are long-lived, then the equation predicts that there are millions of intelligent societies out there, and likely one just a few hundred light years away. That's a long way by spaceship, but really right next door if you're going at the speed of light, which means that our radio telescopes should be able to pick up signals from other advanced beings who want to contact us.

But what if the value of L is low? What if technologically advanced civilizations don't last very long on average? If highly intelligent races tend to perish quickly, then the Drake equation predicts not millions of such civilizations but one. Us. We are alone.

In 1985, Sagan was especially concerned about the 55,000 nuclear warheads strategically placed around the globe, threatening to make Earth a cosmological loser. A recurring theme in these lectures is that our scientific prowess is double-edged, revealing the awesomeness of nature while landing us in great peril.

Yet this is not a dour book. Far from it. Sagan was fundamentally an optimist, and The Varieties of Scientific Experience is mostly a joyful, celebratory meditation on nature and the expansiveness of the human spirit. The volume was published on the 10th anniversary of Sagan's death in December 1996. For those who have sorely missed his clear and wise voice, it will be received as a gift.

Copyright 2007, The Washington Post. All Rights Reserved.

PENGUIN BOOKS

THE VARIETIES OF
SCIENTIFIC EXPERIENCE

Carl Sagan (November 9, 1934–December 20, 1996) was professor of astronomy and space sciences and director of the Laboratory for Planetary Studies at Cornell University. He played a leading role in the Mariner, Viking, and Voyager spacecraft expeditions to the planets, for which he twice received the NASA Medals for Exceptional Scientific Achievement. Dr. Sagan received the Pulitzer Prize and the highest awards of both the National Academy of Sciences and the National Science Foundation and many other awards for his contributions to science, literature, education, and the preservation of the environment. His book Cosmos (accompanying his Emmy and Peabody Award–winning television series of the same name) was the bestselling science book ever published in the English language, and his bestselling novel Contact was turned into a major motion picture.

Dr. Sagan was among the first to alert the public to the danger of global warming and the potential climatic consequences of nuclear war. In the 1980s he initiated the campaign to forge an alliance between religion and science to protect the environment.

THE VARIETIES of SCIENTIFIC EXPERIENCE

A Personal View of the Search for God

CARL SAGAN

Edited by ANN DRUYAN

Illustrations Editor and Scientific Consultant Steven Soter

Editor’s Introduction

Author’s Introduction

1. NATURE AND WONDER: A RECONNAISSANCE OF HEAVEN

2. THE RETREAT FROM COPERNICUS: A MODERN LOSS OF NERVE

3. THE ORGANIC UNIVERSE

4. EXTRATERRESTRIAL INTELLIGENCE

5. EXTRATERRESTRIAL FOLKLORE: IMPLICATIONS FOR THE EVOLUTION OF RELIGION

6. THE GOD HYPOTHESIS

7. THE RELIGIOUS EXPERIENCE

8. CRIMES AGAINST CREATION

9. THE SEARCH

SELECTED Q & A

Acknowledgments

Figure Captions

Index

Editor’s Introduction

Carl Sagan was a scientist, but he had some qualities that I associate with the Old Testament. When he came up against a wall—the wall of jargon that mystifies science and withholds its treasures from the rest of us, for example, or the wall around our souls that keeps us from taking the revelations of science to heart—when he came up against one of those topless old walls, he would, like some latter-day Joshua, use all of his many strengths to bring it down.

As a child in Brooklyn, he had recited the Hebrew V’Ahavta prayer from Deuteronomy at temple services: “And you shall love the Lord your God with all your heart, with all your soul, with all your might.” He knew it by heart, and it may have been the inspiration for him to first ask, What is love without understanding? And what greater might do we possess as human beings than our capacity to question and to learn?

The more Carl learned about nature, about the vastness of the universe and the awesome timescales of cosmic evolution, the more he was uplifted.

Another way in which he was Old Testament: He couldn’t live a compartmentalized life, operating on one set of assumptions in the laboratory and keeping another, conflicting set for the Sabbath. He took the idea of God so seriously that it had to pass the most rigorous standards of scrutiny.

How was it, he wondered, that the eternal and omniscient Creator described in the Bible could confidently assert so many fundamental misconceptions about Creation? Why would the God of the Scriptures be far less knowledgeable about nature than are we, newcomers, who have only just begun to study the universe? He could not bring himself to overlook the Bible’s formulation of a flat, six-thousand-year-old earth, and he found especially tragic the notion that we had been created separately from all other living things. The discovery of our relatedness to all life was borne out by countless distinct and compelling lines of evidence. For Carl, Darwin’s insight that life evolved over the eons through natural selection was not just better science than Genesis, it also afforded a deeper, more satisfying spiritual experience.

He believed that the little we do know about nature suggests that we know even less about God. We had only just managed to get an inkling of the grandeur of the cosmos and its exquisite laws that guide the evolution of trillions if not infinite numbers of worlds. This newly acquired vision made the God who created the World seem hopelessly local and dated, bound to transparently human misperceptions and conceits of the past.

This was no glib assertion on his part. He avidly studied the world’s religions, both living and defunct, with the same hunger for learning that he brought to scientific subjects. He was enchanted by their poetry and history. When he debated religious leaders, he frequently surprised them with his ability to out-quote the sacred texts. Some of these debates led to longstanding friendships and alliances for the protection of life. However, he never understood why anyone would want to separate science, which is just a way of searching for what is true, from what we hold sacred, which are those truths that inspire love and awe.

His argument was not with God but with those who believed that our understanding of the sacred had been completed. Science’s permanently revolutionary conviction that the search for truth never ends seemed to him the only approach with sufficient humility to be worthy of the universe that it revealed. The methodology of science, with its error-correcting mechanism for keeping us honest in spite of our chronic tendencies to project, to misunderstand, to deceive ourselves and others, seemed to him the height of spiritual discipline. 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.

The idea that the scientific method should be applied to the deepest of questions is frequently decried as “scientism.” This charge is made by those who hold that religious beliefs should be off-limits to scientific scrutiny—that beliefs (convictions without evidence that can be tested) are a sufficient way of knowing. Carl understood this feeling, but he insisted with Bertrand Russell that “what is wanted is not the will to believe, but the desire to find out, which is the exact opposite.” And in all things, even when it came to facing his own cruel fate—he succumbed to pneumonia on December 20, 1996, after enduring three bone-marrow transplants—Carl didn’t want just to believe: He wanted to know.

Until about five hundred years ago, there had been no such wall separating science and religion. Back then they were one and the same. It was only when a group of religious men who wished “to read God’s mind” realized that science would be the most powerful means to do so that a wall was needed. These men—among them Galileo, Kepler, Newton, and, much later, Darwin—began to articulate and internalize the scientific method. Science took off for the stars, and institutional religion, choosing to deny the new revelations, could do little more than build a protective wall around itself.

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. Carl believed that our best hope of preserving the exquisite fabric of life on our world would be to take the revelations of science to heart.

And that he did. “Every one of us is, in the cosmic perspective, precious,” he wrote in his book Cosmos. “If a human disagrees with you, let him live. In a hundred billion galaxies you will not find another.” He lobbied NASA for years to instruct Voyager 2 to look back to Earth and take a picture of it from out by Neptune. Then he asked us to meditate on that image and see our home for what it is—just a tiny “pale blue dot” afloat in the immensity of the universe. He dreamed that we might attain a spiritual understanding of our true circumstances. Like a prophet of old, he wanted to arouse us from our stupor so that we would take action to protect our home.

Carl wanted us to see ourselves not as the failed clay of a disappointed Creator but as starstuff, made of atoms forged in the fiery hearts of distant stars. To him we were “starstuff pondering the stars; organized assemblages of 10 billion billion billion atoms considering the evolution of atoms; tracing the long journey by which, here at least, consciousness arose.” For him science was, in part, a kind of “informed worship.” No single step in the pursuit of enlightenment should ever be considered sacred; only the search was.

This imperative was one of the reasons he was willing to get into so much trouble with his colleagues for tearing down the walls that have excluded most of us from the insights and values of science. Another was his fear that we would be unable to keep even the limited degree of democracy we have achieved. Our society is based on science and high technology, but only a small minority among us has even a superficial understanding of how they work. How can we hope to be responsible citizens of a democratic society, informed decision makers regarding the inevitable challenges posed by these newly acquired powers?

This vision of a critically thoughtful public, awakened to science as a way of thinking, impelled him to speak at many places where scientists were not usually found: kindergartens, naturalization ceremonies, an all-black college in the segregated South of 1962, at demonstrations of nonviolent civil disobedience, on the Tonight show. And he did this while maintaining a pioneering, astonishingly productive, fearlessly interdisciplinary scientific career.

He was especially thrilled to be invited to give the Gifford Lectures on Natural Theology of 1985 at the University of Glasgow. He would be following in the footsteps of some of the greatest scientists and philosophers of the last hundred years—including James Frazer, Arthur Eddington, Werner Heisenberg, Niels Bohr, Alfred North Whitehead, Albert Schweitzer, and Hannah Arendt.

Carl saw these lectures as a chance to set down in detail his understanding of the relationship between religion and science and something of his own search to understand the nature of the sacred. In the course of them, he touches on several themes that he had written about elsewhere; however, what follows is the definitive statement of what he took pains to stress were only his personal views on this endlessly fascinating subject.

At the beginning of each Gifford Lecture, a distinguished member of the university community would introduce Carl and marvel at the need for still more additional halls to accommodate the overflow audience. I have been careful not to change the meaning of anything Carl said, but I have taken the liberty of editing out those gracious introductory remarks as well as the hundred or more notations on the audio transcripts that merely say “[Laughter].”

I ask the reader to keep in mind at all times that any deficiencies of this book are my responsibility and not Carl’s. Despite the fact that the unedited transcripts reveal a man who spoke extemporaneously in nearly perfect paragraphs, a collection of lectures is not exactly the same thing as a book. This is especially true when the Pulitzer Prize–winning author in question never published anything without combing at least twenty or twenty-five iterations of every manuscript for error or stylistic infelicity.

There was plenty of laughter during these lectures, but also the kind of pin-drop silence that comes when the audience and the speaker are united in the thrall of an idea. The extended dialogues in some of the question-and-answer periods capture a sense of what it was like to explore a question with Carl. I attended every lecture, and more than twenty years later what remains with me was his extraordinary combination of principled, crystal-clear advocacy coupled with respect and tenderness toward those who did not share his views.

The American psychologist and philosopher William James gave the Gifford Lectures in the first years of the twentieth century. He later turned them into an extraordinarily influential book entitled The Varieties of Religious Experience, which remains in print till this day. Carl admired James’s definition of religion as a “feeling of being at home in the Universe,” quoting it at the conclusion of Pale Blue Dot, his vision of the human future in space. The title of the book you hold in your hands is a tip of the hat to the illustrious tradition of the Gifford Lectures. My variation on James’s title is intended to convey that science opens the way to levels of consciousness that are otherwise inaccessible to us; that, contrary to our cultural bias, the only gratification that science denies to us is deception. I hope it also honors the breadth of searching and the richness of insight that distinguished Carl Sagan’s indivisible life and work. The varieties of his scientific experience were exemplified by oneness, humility, community, wonder, love, courage, remembrance, openness, and compassion.

In that same drawer where the transcript of these lectures was rediscovered, there was a sheaf of notes intended for a book we never had the chance to write. Its working title was Ethos, and it would have been our attempt to synthesize the spiritual perspectives we derived from the revelations of science. We collected filing cabinets’ worth of notes and references on the subject. Among them was a quotation Carl had excerpted from Gottfried Wilhelm Leibniz (1646–1716), the mathematical and philosophical genius, who had invented differential and integral calculus independently of Isaac Newton. Leibniz argued that God should be the wall that stopped all further questioning, as he famously wrote in this passage from Principles of Nature and Grace:

“Why does something exist rather than nothing? For ‘nothing’ is simpler than ‘something.’ Now this sufficient reason for the existence of the universe…which has no need of any other reason…must be a necessary being, else we should not have a sufficient reason with which we could stop.”

And just beneath the typed quote, three small handwritten words in red pen, a message from Carl to Leibniz and to us: “So don’t stop.”

• ANN DRUYAN

Ithaca, New York

March 21, 2006

Author’s Introduction

In these lectures I would like, following the wording of the Gifford Trust, to tell you something of my views on what at least used to be called natural theology, which, as I understand it, is everything about the world not supplied by revelation. This is a very large subject, and I will necessarily have to pick and choose topics. I want to stress that what I will be saying are my own personal views on this boundary area between science and religion. The amount that has been written on the subject is enormous, certainly more than 10 million pages, or roughly 1011 bits of information. That’s a very low lower limit. And nevertheless no one can claim to have read even a tiny fraction of that body of literature or even a representative fraction. So it is only in the hope that much that has been written is unnecessary to be read that one can approach the subject at all. I’m aware of many limitations in the depth and breadth of my own understanding of both subjects, and so ask your indulgence. Fortunately, there was a question period after each of the Gifford Lectures, in which the more egregious of my errors could be pointed out, and I was genuinely delighted by the vigorous give-and-take in those sessions.

Even if definitive statements on these subjects were possible, what follows is not such. My objective is much more modest. I hope only to trace my own thinking and understanding of the subject in the hopes that it will stimulate others to go further, and perhaps through my errors—I hope not to have made many, but it was inevitable that I would—new insights will emerge.

• CARL SAGAN

Glasgow, Scotland

October 14, 1985

THE VARIETIES
of
SCIENTIFIC EXPERIENCE

One

NATURE AND WONDER: A RECONNAISSANCE OF HEAVEN

The truly pious must negotiate a difficult course between the precipice of godlessness and the marsh of superstition.

• Plutarch •

Certainly both extremes are to be avoided, except what are they? What is godlessness? Does not the concern to avoid the “precipice of godlessness” presuppose the very issue that we are to discuss? And what exactly is superstition? Is it just, as some have said, other people’s religion? Or is there some standard by which we can detect what constitutes superstition?

For me, I would say that superstition is marked not by its pretension to a body of knowledge but by its method of seeking truth. And I would like to suggest that superstition is very simple: It is merely belief without evidence. The question of what constitutes evidence in this interesting subject, I will try to address. And I will return to this question of the nature of evidence and the need for skeptical thinking in theological inquiry.

The word “religion” comes from the Latin for “binding together,” to connect that which has been sundered apart. It’s a very interesting concept. And in this sense of seeking the deepest interrelations among things that superficially appear to be sundered, the objectives of religion and science, I believe, are identical or very nearly so. But the question has to do with the reliability of the truths claimed by the two fields and the methods of approach.

By far the best way I know to engage the religious sensibility, the sense of awe, is to look up on a clear night. I believe that it is very difficult to know who we are until we understand where and when we are. I think everyone in every culture has felt a sense of awe and wonder looking at the sky. This is reflected throughout the world in both science and religion. Thomas Carlyle said that wonder is the basis of worship. And Albert Einstein said, “I maintain that the cosmic religious feeling is the strongest and noblest motive for scientific research.” So if both Carlyle and Einstein could agree on something, it has a modest possibility of even being right.

Here are two images of the universe. For obvious reasons they concentrate not on the spaces in which there is nothing but on the locales in which there is something. It would be very dull if I simply showed you image after image of darkness. But I stress that the universe is mainly made of nothing, that something is the exception. Nothing is the rule. That darkness is a commonplace; it is light that is the rarity. As between darkness and light, I am unhesitatingly on the side of light (especially in an illustrated book). But we must remember that the universe is an almost complete and impenetrable darkness and the sparse sources of light, the stars, are far beyond our present ability to create or control. This prevalence of darkness, both factually and metaphorically, is worth contemplating before setting out on such an exploration.

fig. 1

fig. 2

fig. 3

This image is intended for orientation. It is an artist’s impression of the solar system, in which the sizes of the objects but not their relative distances are to scale. And you can see that there are four large bodies other than the Sun, and the rest is debris. We live on the third piece of debris from the Sun; a tiny world of rock and metal with a thin patina—a veneer—of organic matter on the surface, a tiny fraction of which we happen to constitute.

This picture was made by Thomas Wright of Durham, who published an extraordinary book in 1750, which he quite properly called An Original Theory or New Hypothesis of the Universe. Wright was, among other things, an architect and a draftsman. This picture conveys a remarkable sense, for the first time, of looking at the solar system and beyond, to scale. What you can see here is the Sun, and to scale to the size of the Sun is the distance to the orbit of Mercury. Then the planets Venus, Earth, Mars, Jupiter, and Saturn—the other planets were not known in his time—and then, in a wonderful attempt, here is the solar system, the planets we talked about, all in that central dot and a rosette to represent the cometary orbits known in his time. He did not go very far beyond the present orbit of Pluto. And then he imagined, a large distance away, the nearest star then known, Sirius, around which he did not quite have the courage to put another rosette of cometary orbits. But there was the clear sense that our system and the systems of other stars were similar.

fig. 4

Here at upper left is the first of four modern illustrations attempting to show just the same thing, in which we see the Earth on its orbit and the other inner planets. Each little dot is intended to represent a fraction of the plethora of small worlds called asteroids. Beyond them is the orbit of Jupiter. And the distance from the Earth to the Sun represented by the scale bar up at the top is called an astronomical unit. This is the first introduction—there will be many of them that I will talk about—of a kind of geocentric or anthropocentric arrogance with which all of the human attempts to look at the cosmos seem to be infected. The idea that an astronomical unit by which we measure the universe has to do with the Earth’s distance from the Sun is clearly a human pretension. But since it is deeply embedded in astronomy, I will continue to use the word.