"DEMON-HAUNTED WORLD: SCIENCE AS A CANDLE IN THE DARK" by Carl Sagan

• Absence of evidence is not evidence of absence.
• Abuse of children has been implicated as a major probable cause of social problems.
• Always ask whether the hypothesis can be, at least in principle, falsified. Propositions that are untestable, unfalsifiable are not worth much.
• American schoolchildren don’t do enough schoolwork.
• A placebo works only if the patient believes it’s an effective medicine.
• Arguments from authority carry little weight—“authorities” have made mistakes in the past. They will do so again in the future.
• As an inadvertent side effect, the pattern-recognition machinery in our brains is so efficient in extracting a face from a clutter of other detail that we sometimes see faces where there are none.
• As I’ve tried to stress, at the heart of science is an essential balance between two seemingly contradictory attitudes—an openness to new ideas, no matter how bizarre or counterintuitive, and the most ruthlessly skeptical scrutiny of all ideas, old and new.
• As soon as the infant can see, it recognizes faces, and we now know that this skill is hardwired in our brains.
• At high speeds and strong gravitation, Newtonian physics breaks down. THis is one of the great findings of Albert Einstein’s Special and General Relativity, and is one of the reasons his memory is so greatly honored.
• At high speeds and strong gravities, Newtonian physics breaks down. This is one of the great findings of Albert Einstein’s Special and General Relativity, and is one of the reasons his memory is so greatly honored.
• At least 1 percent of all of us is schizophrenic. This amounts to over 50 million schizophrenics on the planet, more than the population of, say, England.
• At the heart of some pseudoscience (and some religion also, New Age and Old) is the idea that wishing makes it so.
• Authorities must prove their contentions like everybody else.
• A vector, written in boldface type, is any quantity with both a magnitude and a direction.
• Avoidable human misery is more often caused not so much by stupidity as by ignorance, particularly our ignorance about ourselves.
• Because science carries us toward an understanding of how the world is, rather than how we would wish it to be, its findings may not in all cases be immediately comprehensible or satisfying.
• Better the hard truth, I say, than the comforting fantasy. And in the final tolling it often turns out that the facts are more comforting than the fantasy.
• Books are key to understanding the world and participating in a democratic society,
• Books are key to understanding the world and participating in a democratic society.
• 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, drawn from the entire planet and from all of our history.
• But hypnosis is an unreliable way to refresh memory. It often elicits imagination, fantasy, and play as well as true recollections, with neither patient nor therapist able to distinguish the one from the other.
• By making pronouncements that are, even if only in principle, testable, religions, however unwillingly, enter the arena of science.
• censoring knowledge, telling people what they must think, is the aperture to thought police, foolish and incompetent decision-making, and long-term decline.
• Children need hands-on experience with the experimental method rather than just reading about science in a book.
• Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder.
• Constantine the Great is the Emperor who made Christianity the official religion of the Roman Empire.
• Control experiments are essential.
• Don’t talk to the general audience as you would to your scientific colleagues. There are terms that convey your meaning instantly and accurately to fellow experts. You may parse these phrases every day in your professional work. But they do no more than mystify an audience of nonspecialists. Use the simplest possible language.
• Don’t waste neurons on what doesn’t work. Devote those neurons to new ideas that better explain the data.
• Each field of science has its own complement of pseudoscience.
• Encourage substantive debate on the evidence by knowledgeable proponents of all points of view.
• Essentially all the UFO cases were anecdotes, something asserted.
• Euphemisms for ware are one of a broad class of reinventions of language for political purposes.
• Every generation worries that educational standards are decaying.
• every question is a cry to understand the world.* There is no such thing as a dumb question.
• Everything hinges on the matter of evidence. On so important a question, the evidence must be airtight. The more we want it to be true, the more careful we have to be.
• Everything hinges on the matter of evidence. On so important a question, the evidence must be airtight. The more we want it to be true, the more careful we have to be. No witness’s say-so is good enough. People make mistakes.
• Every time a scientific paper presents a bit of data, it’s accompanied by an error bar—a quiet but insistent reminder that no knowledge is complete or perfect.
• Except for hydrogen, all the atoms that make each of us up--the iron in our blood, the calcium in our bones, the carbon in our brains--were manufactured in red giant stars thousands of lightyears away in space and billions of years ago in time. We are, as I like to say, stardust.
• Except in pure mathematics, nothing is known for certain (although much is certainly false).
• Extraterrestrials represent a hypothesis of last resort. You reach for it only if everything else fails.
• Five to ten percent of us are extremely suggestible, able to move at a command into a deep hypnotic trance.
• Frederick Douglass taught that literacy is the path from slavery to freedom. There are many kinds of slavery and many kinds of freedom. But reading is still the path.
• Fundamental research, research into the heart of Nature, is the means by which we acquire the new knowledge that gets applied.
• Hallucinations are common. If you have one, it doesn’t mean you’re crazy.
• High-quality early education programs such as Head Start can be enormously successful in preparing children for reading.
• History generally is written by the victors to justify their actions, to arouse patriotic fervor, and to suppress the legitimate claims of the vanquished.
• How can we affect national policy--or even make intelligent decision in our own lives--if we don’t grasp the underlying issues?
• If I’m serious about understanding the world, thinking with anything besides my brain, as tempting as that might be, is likely to get me into trouble. Really, it’s okay to reserve judgement until the evidence is in.
• If it’s sometimes easier to reject strong evidence than to admit that we’ve been wrong, this is also information about ourselves worth having.
• If it were widely understood that claims of knowledge requires adequate evidence before they can be accepted, there would be no more room for pseudoscience.
• If it were widely understood that claims to knowledge require adequate evidence before they can be accepted, there would be no room for pseudoscience.
• If our nation can’t manufacture, at high quality and low price, products people want to buy, then industries will continue to drift away and transfer a little more prosperity to other parts of the world.
• • If there’s a chain of argument, every link in the chain must work (including the premise)—not just most of them.
• If there’s a chain of argument, every link in the chain must work (including the premise)--not just most of them.
• If we can’t think for ourselves, if we’re unwilling to question authority, then we’re just putty in the hands of those in power.
• If you’ve never heard of science (to say nothing of how it works), you can hardly be aware you’re embracing pseudoscience.
• If you’ve never heard of science (to say nothing of how it works), you can hardly be aware you’re embracing pseudoscience. You’re simply thinking in one of the ways that humans always have.
• Ignorance feeds on ignorance. Science phobia is contagious.
• In science the theories are always being reassess and confronted with new facts; if the facts are seriously discordant--beyond the error bars--the theory may have to be revised.
• instant. A key tool is the so-called “cold read,” a statement of opposing predispositions so tenuously balanced that anyone will recognize a grain of truth.
• Instead of acknowledging that in many areas we are ignorant, we have tended to say things like the Universe is permeated with the ineffable. A God of the Gaps is assigned responsibility for what we do not yet understand.
• It is certainly true that all beliefs and all myths are worthy of a respectful hearing. It is not true that al folk beliefs are equally valid--if we’re talking not about an internal mindset, but about understanding the external reality.
• It is possible--given absolute control over the media and the police--to rewrite the memories of hundreds of millions of people, if you have a generation to accomplish it in.
• It is telling that alien abductions occur mainly on falling asleep or when waking up, or on long automobile drives where there is a well known danger of falling into some autohypnotic reverie.
• It’s a stimulating exercise to think of questions to which no human today knows the answers, but where a correct answer would immediately be recognized as such.
• Keeping an open mind is a virtue—but, as the space engineer James Oberg once said, not so open that your brains fall out.
• Like an earthquake that rattles our faith in the very ground we’re standing on, challenging our accustomed beliefs, shaking the doctrines we have grown to rely upon can be profoundly disturbing.
• Longevity is perhaps the best single measure of the physical quality of life.
• Magic requires tacit cooperation of the audience with the magician--an abandonment of skepticism, or what is sometimes described as the willing suspension of disbelief. It immediately follows that to penetrate the magic, to expose the trick, we must cease collaborating.
• Magic requires tacit cooperation of the audience with the magician—an abandonment of skepticism, or what is sometimes described as the willing suspension of disbelief. It immediately follows that to penetrate the magic, to expose the trick, we must cease collaborating.
• Maxwell’s greatest contribution was his discovery that electricity and magnetism, of all things, join together to become light.
• Memory can be contaminated. False memories can be implanted even in minds that do not consider themselves vulnerable and uncritical.
• Microbiology and meteorology now explain what only a few centuries ago was considered sufficient cause to burn women to death.
• Most American children aren’t stupid. Part of the reason they don’t study hard is that they receive few tangible benefits when they do.
• Never forget that native intelligence is widely distributed in our species. Indeed, it is the secret of our success.
• No anecdotal claim--no matter how sincere, no matter how deeply felt, no matter how exemplary the lives of the attesting citizens--carries much weight on so important a question.
• Not all claims to knowledge have equal merit.
• Not every branch of science can foretell the future--paleontology can’t--but many can and with stunning accuracy.
• Not every branch of science can foretell the future—paleontology can’t—but many can and with stunning accuracy.
• Not until the eighteenth century was mental illness no longer generally ascribed to supernatural causes; even insomnia had been considered a punishment inflicted by demons.) More than half of Americans tell pollsters they “believe” in the Devil’s existence, and 10 percent have communicated with him, as Martin Luther reported he did regularly.
• No witness’s say-so is good enough. People make mistakes. People play practical jokes. People stretch the truth for money or attention or fame. People occasionally misunderstand what they’re seeing. People sometimes even see things that aren’t there.
• Now, what’s the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there’s no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists? Your inability to invalidate my hypotheses is not at all the same thing as proving it true. Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder. What I’m asking you to do comes down to believing, in the absence of evidence, on my say-so.
• Occam’s Razor. This convenient rule-of-thumb urges us when faced with two hypotheses that explain the data equally well to choose the simpler.
• Of course we must be willing to change our minds when warranted by new evidence. But the evidence must be strong.
• Of course we must be willing to change our minds when warranted by new evidence. But the evidence must be strong. Not all claims to knowledge have equal merit.
• Once you give a charlatan power over you, you almost never get it back.
• One of the great commandments of science is, “Mistrust arguments from authority.”
• One of the great commandments of science is, “Mistrust arguments from authority.” Too many such arguments have proved too painfully wrong. Authorities must prove their contentions like everybody else.
• One of the reasons for its success is that science has built-in, error-correcting machinery at its very heart.
• One of the saddest lessons of history is this: If we’ve been bamboozled long enough, we tend to reject any evidence of the bamboozle.
• Our memories are fallible; even scientific truth is merely an approximation; and we are ignorant about nearly all of the Universe.
• Our perceptions are fallible. We sometimes see what isn’t there. We are prey to optical illusions. Occasionally we hallucinate. We are error-prone.
• Part of the duty of citizenship is not to be intimidated into conformity.
• Part of the reason that children are afraid of the dark may be that, in our entire evolutionary history up until just a moment ago, they never slept alone.
• Plainly there is no way back. Like it or not, we are stuck with science. We had better make the best of it.
• Propositions that are untestable, unfalsifiable are not worth much.
• Pseudoscience differs from erroneous science. Science thrives on errors, cutting them away one by one. False conclusions are drawn all the time, but they are drawn tentatively. Hypotheses are framed so they are capable of being disproved. A succession of alternative hypotheses is confronted by experiment and observation. Science gropes and staggers toward improved understanding.
• Pseudoscience is just the opposite. Hypotheses are often framed precisely so they are invulnerable to any experiment that offers a prospect of disproof, so even in principle they cannot be invalidated.
• Pseudoscience is just the opposite. Hypothesis are often framed precisely so they are invulnerable to any experiment that offers a prospect of disproof, so even in principle they cannot be invalidated.
• Pseudoscience speaks to powerful emotional needs that science often leaves unfulfilled.
• Pseudoscience speaks to powerful emotional needs that science often leaves unfulfilled. It caters to fantasies about personal pers we lack and long for (like those attributed to comic book superheros today, and earlier, to the gods).
• Quantify. If whatever it is you’re explaining has some measure, some numerical quantity attached to it, you’ll be much better able to discriminate among competing hypotheses. What is vague and qualitative is open to many explanations.
• Roughly half the scientists on Earth work at least part-time for the military.
• Science alerts us to the perils introduced by our world-altering technologies, especially to the global environment on which our lives depend.
• Science confers power on anyone who takes the trouble to learn it.
• Science is an attempt, largely successful, to understand the world, to get a grip on things, to get hold of ourselves, to steer a safe course.
• Science is a way to call the bluff of those who only pretend to knowledge.
• Science is far from a perfect instrument of knowledge. It’s just the best we have.
• Science is more than a body of knowledge; it is a way of thinking.
• Science permits the Earth to feed about a hundred times more humans, and under conditions much less grim, than it could a few thousand years ago.
• Science thrives on errors, cutting them away one by one. False conclusions are drawn all the time, but they are drawn tentatively. Hypotheses are framed so they are capable of being disproved.
• Scientists do not constitute a voting bloc. They have no effective lobby. However, much of their work is in everybody’s interest.
• Skepticism challenges established institutions.
• Skepticism does not sell well.
• Special cautions are necessary when the stakes are high. We are not obliged to make up our minds before the evidence is in. It’s permitted not to be sure.
• Spin more than one hypothesis. If there’s something to be explained, think of all the different ways in which it could be explained. Then think of tests by which you might systematically disprove each of the alternatives. What survives, the hypothesis that resists disproof in this Darwinian selection among “multiple working hypotheses,” has a much better chance of being the right answer than if you had simply run with the first idea that caught your fancy.
• Spurious accounts that snare the gullible are readily available. Skeptical treatments are much harder to find.
• Such “explanations” can explain anything, and therefore in fact nothing.
• Survival comes first. Growth comes second.
• Tellingly, pseudoscience and superstition tend to recognize no constraints in Nature. Instead, “all things are possible.”
• That there are things seen which the ordinary observer, or even an occasional expert, does not understand is inevitable.
• That there are things seen which the ordinary observer, or even an occasional expert, does not understand is inevitable. But why, if we see something we don’t recognize, should we conclude it’s a ship from the stars? A wide variety of more prosaic possibilities present themselves.
• The capacity to establish and maintain clear distinctions between the life of dreams and life in the outside world is hard-won and requires several years to accomplish, not being completed even in normal children before ages eight to ten.
• The consequences of scientific illiteracy are far more dangerous in our time than in any that has come before it.
• The Department of Defense, like similar ministries in every nation, thrives on enemies, real or imagined.
• The directly observed success of science is the reason I advocate its use. If something else worked better, I would advocate the something else.
• The dumbing down of America is most evident in the slow decay of substantive content in the enormously influential media.
• The dumbing down of America is most evident in the slow decay of substantive content in the enormously influential media, the 30-second sound bites (now down to 10 seconds or less), lowest common denominator programming, credulous presentations on pseudoscience and superstition, but especially a kind of celebration of ignorance.
• The fact is that far more crime and child abuse has been committed by zealots in the name of God, Jesus, and Mohammed than has ever been committed in the name of Satan. Man people don’t like that statement, but few can argue with it.
• The fact that so little of the findings of modern science is prefigured in Scripture to my mind casts further doubt on its divine inspiration.
• the hard but just rule is that if the ideas don’t work, you must throw them away.
• The hydrogen bomb is by far the most horrific weapon ever invented.
• The last scientifically literate President may have been THomas Jefferson.
• The method of science, as stodgy and grumpy as it may seem, is far more important than the findings of science.
• The most each generation can hope for is to reduce the error bars a little, and to add to the body of data to which error bars apply.
• The only sure way to test your adversary’s defenses is to fly an aircraft over their borders and see how long it takes for them to notice.
• The pattern-recognition machinery in our brains is so efficient in extracting a face from a clutter of other detail that we sometimes see faces where there are none.
• The question, as always, is how good is the evidence? The burden of proof surely rests on the shoulders of those who advance such claims.
• There are no forbidden questions in science, no matters too sensitive or delicate to be probed, no sacred truths.
• There is a pressing national need for more public knowledge of science.
• The reliance on carefully designed and controlled experiments is key, as I tried to stress earlier.
• There’s a reason people are nervous about science and technology.
• The scientific treatments are hundreds of thousands of times more effective than the alternatives.
• The tenets of skepticism do not require an advanced degree to master, as most successful used car buyers demonstrate.
• The truth may be puzzling or counterintuitive. It may contradict deeply held beliefs. Experiment is how we get a handle on it.
• Those described as gifted psychics find that their powers diminish markedly whenever skeptics arrive, and disappear altogether in the presence of a conjurer as skilled as James Randi.
• Those who want to know what actually happened will become fully conversant with the view of historians in other, once adversary, nations.
• Try not to get overly attached to a hypothesis just because it’s yours.
• Valid criticism does you a favor.
• Variables must be separated.
• We are all flawed and creatures of our times.
• We don’t have to understand the theory to see what it predicts.
• We need more money for teachers’ training and salaries, and for laboratories.
• We’re good in some things, but not in everything. Wisdom lies in understanding our limitations.
• We’re more closely related to chimps than rats are to mice.
• We seek a pattern, and we find one.
• We’ve not yet found compelling evidence for life beyond the Earth.
• We would surely be missing something important about our own nature if we refused to face up to the fact that hallucinations are part of being human.
• We would surely be missing something important about our own nature if we refused to face up to the fact that hallucinations are part of being human. However, none of this makes hallucinations part of an external rather than an internal reality.
• What a more critical mind might recognize as a hallucination or a dream, a more credulous mind interprets as a glimpse of an elusive but profound external reality.
• Whatever the problem, the quick fix is to shave a little freedom off the Bill of Rights.
• What skeptical thinking boils down to is the means to construct, and to understand, a reasoned argument and—especially important—to recognize a fallacious or fraudulent argument.
• What skeptical thinking boils down to is the means to construct, and to understand, a reasoned argument and--especially important--to recognize a fallacious or fraudulent argument. The question is not whether we like the conclusion that emerges out of a train of reasoning, but whether the conclusions follows from the premise or starting point and whether that premise is true.
• What the public understands and appreciates, it is more likely to support.
• When the pseudo scientific hypothesis fails to catch fire with scientists, conspiracies to suppress it are deduced.
• when what needs to be learned changes quickly, especially in the course of a single generation, it becomes much harder to know what to teach and how to teach it.
• Wherever possible there must be independent confirmation of the “facts.”
• Whose interest does ignorance serve?
• Wisdom lies in understanding our limitations.
• With a few exceptions, secrecy is deeply incompatible with democracy and with science.
• Your inability to invalidate my hypothesis is not at all the same thing as proving it true.