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Carl Sagan Quotes
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Carl Edward Sagan was an American astronomer, cosmologist, astrophysicist, astrobiologist, author, science popularizer, and science communicator in astronomy and other natural sciences. He is best known as a science popularizer and communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space: the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued the now accepted hypothesis that the high surface temperatures of Venus can be attributed to and calculated using the greenhouse effect.Sagan published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books. He wrote many popular science books, such as The Dragons of Eden, Broca's Brain and Pale Blue Dot, and narrated and co-wrote the award-winning 1980 television series Cosmos: A Personal Voyage. The most widely-watched series in the history of American public television, Cosmos has been seen by at least 500 million people across 60 different countries. The book Cosmos was published to accompany the series. He also wrote the science fiction novel Contact, the basis for a 1997 film of the same name. His papers, containing 595,000 items, are archived at The Library of Congress.Sagan advocated scientific skeptical inquiry and the scientific method, pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence . He spent most of his career as a professor of astronomy at Cornell University, where he directed the Laboratory for Planetary Studies. Sagan and his works received numerous awards and honors, including the NASA Distinguished Public Service Medal, the National Academy of Sciences Public Welfare Medal, the Pulitzer Prize for General Non-Fiction for his book The Dragons of Eden, and, regarding Cosmos: A Personal Voyage, two Emmy Awards, the Peabody Award, and the Hugo Award. He married three times and had five children. After suffering from myelodysplasia, Sagan died of pneumonia at the age of 62, on December 20, 1996. Wikipedia  

✵ 9. November 1934 – 20. December 1996  •  Other names Karl Seýgan
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Carl Sagan: 365 quotes51 likes

Carl Sagan Quotes

“War is murder writ large.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 326

“Our loyalties are to the species and the planet. We speak for Earth. Our obligation to survive and flourish is owed not just to ourselves, but also to that Cosmos, ancient and vast, from which we spring.”

Carl Sagan

54 min 25 sec
Cosmos: A Personal Voyage (1990 Update), Who Speaks for Earth? [Episode 13]

“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.”

Carl Sagan

1 min 10 sec
Cosmos: A Personal Voyage (1990 Update), Encyclopedia Galactica [Episode 12]

“For as long as there been humans we have searched for our place in the cosmos. Where are we? Who are we? We find that we live on an insignificant planet of a hum-drum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people. This perspective is a courageous continuation of our penchant for constructing and testing mental models of the skies; the Sun as a red-hot stone, the stars as a celestial flame, the Galaxy as the backbone of night.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 193

“We are set irrevocably, I believe, on a path that will take us to the stars—unless in some monstrous capitulation to stupidity and greed, we destroy ourselves first.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 25, “The Amniotic Universe” (p. 368)

“In any case, we do not advance the human cause by refusing to consider ideas that make us frightened.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 25, “The Amniotic Universe” (p. 364)

“It is a good idea not to make up our minds prematurely on this issue. It is probably best not to let our personal preferences influence the decision. Rather, in the long tradition of successful science, we should permit nature to reveal the truth to us.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 24, “Gott and the Turtles” (p. 351)

“Proponents of doctrinal religions—ones in which a particular body of belief is prized and infidels scorned—will be threatened by the courageous pursuit of knowledge. We hear from such people that it may be dangerous to probe too deeply. Many people have inherited their religion like their eye color: they consider it not a thing to think very deeply about, and in any case beyond our control. But those with a set of beliefs they profess to feel deeply about, which they have selected without an unbiased sifting through the facts and the alternatives, will feel uncomfortably challenged by searching questions. Anger at queries about our beliefs is the body’s warning signal: here lies unexamined and probably dangerous doctrinal baggage.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (pp. 339-340)

“The way to find out about our place in the universe is by examining the universe and by examining ourselves—without preconceptions, with as unbiased a mind as we can muster. We cannot begin with an entirely clean slate, since we arrive at this problem with predispositions of hereditary and environmental origin; but, after understanding such built-in biases, is it not possible to pry insights from nature?”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (p. 339)

“The First Amendment to the United States Constitution encourages a diversity of religions but does not prohibit criticism of religion. In fact it protects and encourages criticism of religion. Religions ought to be subject to at least the same degree of skepticism as, for example, contentions about UFO visitations or Velikovskian catastrophism. I think it is healthy for the religions themselves to foster skepticism about the fundamental underpinnings of their evidential bases. There is no question that religion provides a solace and support, a bulwark in time of emotional need, and can serve extremely useful social roles. But it by no means follows that religion should be immune from testing, from critical scrutiny, from skepticism. It is striking how little skeptical discussion of religion there is in the nation that Tom Paine, the author of The Age of Reason, helped to found. I hold that belief systems that cannot survive scrutiny are probably not worth having.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (p. 338)

“But there is a chance that the answers will discomfit a great many bureaucratic and doctrinal religions. The idea of religion as a body of belief, immune to criticism, fixed forever by some founder is, I think, a prescription for the long-term decay of the religion, especially lately.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (p. 338)

“The idea that a God or gods is necessary to effect one or more of these origins has been under repeated attack over the last few thousand years. Because we know something about phototropism and plant hormones, we can understand the opening of the morning glory independent of divine microintervention. It is the same for the entire skein of causality back to the origin of the universe. As we learn more and more about the universe, there seems less and less for God to do.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (p. 335)

“It is astonishing in the face of such transparent evasions that this religion has any adherents at all. But religions are tough. Either they make no contentions which are subject to disproof or they quickly redesign doctrine after disproof. The fact that religions can be so shamelessly dishonest, so contemptuous of the intelligence of their adherents, and still flourish does not speak very well for the tough-mindedness of the believers. But it does indicate, if a demonstration were needed, that near the core of the religious experience is something remarkably resistant to rational inquiry.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (pp. 332-333)

“Many scientists deeply involved in the exploration of the solar system (myself among them) were first turned in that direction by science fiction. And the fact that some of that science fiction was not of the highest quality is irrelevant. Ten-year-olds do not read the scientific literature.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 9, “Science Fiction—A Personal View” (p. 172)

“In the face of all this, many of the standard ideas of science fiction seem to me to pale by comparison. I see the relative absence of these things and the distortions of scientific thinking often encountered in science fiction as terrible wasted opportunities. Real science is as amenable to exciting and engrossing fiction as fake science, and I think it is important to exploit every opportunity to convey scientific ideas in a civilization which is both based upon science and does almost nothing to ensure that science is understood.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 9, “Science Fiction—A Personal View” (p. 166)

“St. Anselm argued that since we can imagine a perfect being, he must exist—because he would not be perfect without the added perfection of existence. This so-called ontological argument was more or less promptly attacked on two grounds: (1) Can we imagine a completely perfect being? (2) Is it obvious that perfection is augmented by existence? To the modern ear such pious arguments seem to be about words and definitions rather than about external reality.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 8, “Norman Bloom, Messenger of God” (p. 152)

“Vigorous criticism is more constructive in science than in some other areas of human endeavor because in science there are adequate standards of validity that can be agreed upon by competent practitioners the world over. The objective of such criticism is not to suppress but rather to encourage the advance of new ideas: those that survive a firm skeptical scrutiny have a fighting chance of being right, or at least useful.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 7, “Venus and Dr. Velikovsky” (p. 98)

“A clear prediction in an area undergoing vigorous study permits doctrines to be subject to disproof. The last posture a bureaucratic religion wishes to find itself in is vulnerability to disproof, where an experiment can be performed on which the religion stands or falls.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (p. 332)

“Very few scientists actually plunge into the murky waters of testing or challenging borderline or pseudo-scientific beliefs. The chance of finding out something really interesting—except about human nature—seems small, and the amount of time required seems large. I believe that scientists should spend more time in discussing these issues, but the fact that a given contention lacks vigorous scientific opposition in no way implies that scientists think it is reasonable.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 5, “Night Walkers and Mystery Mongers: Sense and Nonsense at the End of Science” (p. 69)

“But our openness to the dazzling possibilities presented by modern science must be tempered by some hard-nosed skepticism. Many interesting possibilities simply turn out to be wrong. An openness to new possibilities and a willingness to ask hard questions are both required to advance our knowledge. And the asking of tough questions has an ancillary benefit: political and religious life in America, especially in the last decade and a half, has been marked by an excessive public credulity, an unwillingness to ask difficult questions, which has produced a demonstrable impairment in our national health. Consumer skepticism makes quality products. This may be why governments and churches and school systems do not exhibit unseemly zeal in encouraging critical thought. They know they themselves are vulnerable.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 5, “Night Walkers and Mystery Mongers: Sense and Nonsense at the End of Science” (pp. 68-69)

“For many people, the shoddily thought out doctrines of borderline science are the closest approximation to comprehensible science readily available. The popularity of borderline science is a rebuke to the schools, the press and commercial television for their sparse, unimaginative and ineffective efforts at science education; and to us scientists, for doing so little to popularize our subject.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 5, “Night Walkers and Mystery Mongers: Sense and Nonsense at the End of Science” (p. 63)

“Both Barnum and H. L. Mencken are said to have made the depressing observation that no one ever lost money by underestimating the intelligence of the American public. The remark has worldwide application. But the lack is not in intelligence, which is in plentiful supply; rather, the scarce commodity is systematic training in critical thinking.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 5, “Night Walkers and Mystery Mongers: Sense and Nonsense at the End of Science” (pp. 58-59)

“Our perceptions may be distorted by training and prejudice or merely because of the limitations of our sense organs, which, of course, perceive directly but a small fraction of the phenomena of the world. Even so straightforward a question as whether in the absence of friction a pound of lead falls faster than a gram of fluff was answered incorrectly by Aristotle and almost everyone else before the time of Galileo. Science is based on experiment, on a willingness to challenge old dogma, on an openness to see the universe as it really is. Accordingly, science sometimes requires courage—at the very least the courage to question the conventional wisdom.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter , “” (pp. 15-16)

“All inquiries carry with them some element of risk. There is no guarantee that the universe will conform to our predispositions. But I do not see how we can deal with the universe—both the outside and the inside universe—without studying it. The best way to avoid abuses is for the populace in general to be scientifically literate, to understand the implications of such investigations. In exchange for freedom of inquiry, scientists are obliged to explain their work. If science is considered a closed priesthood, too difficult and arcane for the average person to understand, the dangers of abuse are greater. But if science is a topic of general interest and concern—if both its delights and its social consequences are discussed regularly and competently in the schools, the press, and at the dinner table—we have greatly improved our prospects for learning how the world really is and for improving both it and us.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 1, “Broca’s Brain” (pp. 13-14)

“Society corrupts the best of us. It is a little unfair, I think, to criticize a person for not sharing the enlightenment of a later epoch, but it is also profoundly saddening that such prejudices were so extremely pervasive. The question raises nagging uncertainties about which of the conventional truths of our own age will be considered unforgivable bigotry by the next.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 1, “Broca’s Brain” (p. 11)

“The well-meaning contention that all ideas have equal merit seems to me little different from the disastrous contention that no ideas have any merit.”

Carl Sagan book Broca's Brain

Introduction (p. xii)
Broca's Brain (1979)

“Both borderline science and many religions are motivated in part by a serious concern about the nature of the universe and our role in it, and for this reason merit our consideration and regard. In addition, I think it possible that many religions involve at their cores an attempt to come to grips with profound mysteries of our individual life histories, as described in the last chapter. But both in borderline science and in organized religion there is much that is specious or dangerous. While the practitioners of such doctrines often wish there were no criticisms to which they are expected to reply, skeptical scrutiny is the means, in both science and religion, by which deep insights can be winnowed from deep nonsense.”

Carl Sagan book Broca's Brain

Introduction (p. xii)
Broca's Brain (1979)

“Natural selection has served as a kind of intellectual sieve, producing brains and intelligences increasingly competent to deal with the laws of nature. This resonance, extracted by natural selection, between our brains and the universe may help explain a quandary set by Einstein: The most incomprehensible property of the universe, he said, is that it is so comprehensible.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 9, “Knowledge is Our Destiny: Terrestrial and Extraterrestrial Intelligence” (pp. 242-243)

“The entire evolutionary record on our planet, particularly the record contained in fossil endocasts, illustrates a progressive tendency toward intelligence. There is nothing mysterious about this: smart organisms by and large survive better and leave more offspring than stupid ones.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 9, “Knowledge is Our Destiny: Terrestrial and Extraterrestrial Intelligence” (p. 240)

“That in nonarithmetic operations the small and slow human brain can still do so much better than the large and fast electronic computer is an impressive tribute to how cleverly the brain is packaged and programmed—features brought about, of course, by natural selection. Those who possessed poorly programmed brains eventually did not live long enough to reproduce.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 8, “The Future Evolution of the Brain” (p. 224)

“Without these experimental tests, very few physicists would have accepted general relativity. There are many hypotheses in physics of almost comparable brilliance and elegance that have been rejected because they did not survive such a confrontation with experiment. In my view, the human condition would be greatly improved if such confrontations and willingness to reject hypotheses were a regular part of our social, political, economic, religious and cultural lives.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 7, “Lovers and Madmen” (p. 193)

“The search for patterns without critical analysis, and rigid skepticism without a search for patterns, are the antipodes of incomplete science. The effective pursuit of knowledge requires both functions.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 7, “Lovers and Madmen” (p. 192)

“There is no way to tell whether the patterns extracted by the right hemisphere are real or imagined without subjecting them to left-hemisphere scrutiny. On the other hand, mere critical thinking, without creative and intuitive insights, without the search for new patterns, is sterile and doomed. To solve complex problems in changing circumstances requires the activity of both cerebral hemispheres: the path to the future lies through the corpus callosum.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 7, “Lovers and Madmen” (pp. 190-191)

“There is no doubt that right-hemisphere intuitive thinking may perceive patterns and connections too difficult for the left hemisphere; but it may also detect patterns where none exist. Skeptical and critical thinking is not a hallmark of the right hemisphere. And unalloyed right-hemisphere doctrines, particularly when they are invented during new and trying circumstances, may be erroneous or paranoid.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 7, “Lovers and Madmen” (p. 189)

“Evolution often uses this strategy. Indeed, the standard evolutionary practice of increasing the amount of genetic information as organisms increase in complexity is accomplished by doubling part of the genetic material and then allowing the slow specialization of function of the redundant set.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 7, “Lovers and Madmen” (p. 183)

“The price we pay for the anticipation of our future is anxiety about it. Foretelling disaster is probably not much fun; Pollyanna was much happier than Cassandra. But the Cassandric components of our nature are necessary for survival.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 3, “The Brain and the Chariot” (p. 74)

“There is a popular contention that half or more of the brain is unused. From an evolutionary point of view this would be quite extraordinary: why should it have evolved if it had no function? But actually the statement is made on very little evidence.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 2, “Genes and Brains” (p. 31)

“Note that in all this interaction between mutation and natural selection, no moth is making a conscious effort to adapt to a changed environment. The process is random and statistical.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 2, “Genes and Brains” (p. 28)

“A mutation in a DNA molecule within a chromosome of a skin cell in my index finger has no influence on heredity. Fingers are not involved, at least directly, in the propagation of the species.”

Carl Sagan

Source: The Dragons of Eden (1977), Chapter 2, “Genes and Brains” (p. 27)

“At any rate, both because of the clear trend in the recent history of biology and because there is not a shred of evidence to support it, I will not in these pages entertain any hypotheses on what used to be called the mind-body dualism, the idea that inhabiting the matter of the body is something made of quite different stuff, called mind.”

Carl Sagan

Introduction (p. 7)
The Dragons of Eden (1977)

“The entire recent history of biology shows that we are, to a remarkable degree, the results of the interactions of an extremely complex array of molecules; and the aspect of biology that was once considered its holy of holies, the nature of the genetic material, has now been fundamentally understood in terms of the chemistry of its constituent nucleic acids, DNA and RNA, and their operational agents, the proteins.”

Carl Sagan

Introduction (p. 7)
The Dragons of Eden (1977)

“I proffer the following ideas with a substantial degree of trepidation; I know very well that many of them are speculative and can be proved or disproved on the anvil of experiment.”

Carl Sagan

Introduction (p. 5)
The Dragons of Eden (1977)

“Whether we believe in God depends very much on what we mean by God.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 23, “A Sunday Sermon” (p. 330)

“The best antidote for pseudoscience, I firmly believe, is science.”

Carl Sagan book Broca's Brain

Source: Broca's Brain (1979), Chapter 5, “Night Walkers and Mystery Mongers: Sense and Nonsense at the End of Science” (p. 75)