The Demon-Haunted World: Science as a Candle in the Dark

by Carl Sagan

The method of science, as stodgy and grumpy as it may seem, is far more important than the findings of science.

We’ve arranged a global civilization in which most crucial elements—transportation, communications, and all other industries; agriculture, medicine, education, entertainment, protecting the environment; and even the key democratic institution of voting—profoundly depend on science and technology. We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster.

One of the great commandments of science is, “Mistrust arguments from authority.”

Authorities must prove their contentions like everybody else.

Science is not only compatible with spirituality; it is a profound source of spirituality. When we recognize our place in an immensity of light-years and in the passage of ages, when we grasp the intricacy, beauty, and subtlety of life, then that soaring feeling, that sense of elation and humility combined, is surely spiritual.

Scientists are intent on testing those theories to the breaking point. They do not trust what is intuitively obvious. That the Earth is flat was once obvious. That heavy bodies fall faster than light ones was once obvious. That bloodsucking leeches cure most diseases was once obvious. That some people are naturally and by divine decree slaves was once obvious. That there is such a place as the center of the Universe, and that the Earth sits in that exalted spot was once obvious. That there is an absolute standard of rest was once obvious. The truth may be puzzling or counterintuitive. It may contradict deeply held beliefs. Experiment is how we get a handle on it.

In the long run, the greatest gift of science may be in teaching us, in ways no other human endeavor has been able, something about our cosmic context, about where, when, and who we are.

This kind of hypothesis is falsifiable, a property that brings it well into the scientific arena.

“For all I know, they could be the product of active imaginations. But because we’re a tabloid, we don’t have to question ourselves out of a story.”

Skepticism doesn’t sell newspapers.

There are wonders enough out there without our inventing any.

We’re more closely related to chimps than rats are to mice.

But if the suspected signal isn’t available for every grumpy skeptic to pick over, we cannot call it evidence of extraterrestrial life—no matter how appealing we find the notion.

New and better information might emerge, for all we know, tomorrow.

The tenets of skepticism do not require an advanced degree to master, as most successful used car buyers demonstrate.

“Do you believe in UFOs?” I’m always struck by how the question is phrased, the suggestion that this is a matter of belief and not of evidence.

If Anne Jefferies had grown up in a culture touting aliens rather than fairies, and UFOs rather than castles in the air, would her story have been distinguishable in any significant respect from the ones “abductees” tell?

Credulity performed the office of faith; fanaticism was permitted to assume the language of inspiration,

and the effects of accident or contrivance were ascribed to supernatural causes …

Any protozoology or bacteriology or mycology textbook is filled with wonders that far outshine the most exotic descriptions of the alien abductionists.

The believers take the common elements in their stories as tokens of verisimilitude, rather than as evidence that they have contrived their stories out of a shared culture and biology.

The situation is rather like the method of science itself—where many isolated data points can be remembered, summarized, and explained in the framework of a theory. We then much more easily recall the theory and not the data.

It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.

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.

Most medical curricula include significant exposure to scientific results and methods. But many of those dealing with abuse cases seem to have at best a casual acquaintance with science.

Why should we suppose that, of the vast treasure of memories stored in our heads, none of it could have been implanted after the event—by how a question is phrased when we’re in a suggestible frame of mind, by the pleasure of telling or hearing a good story, by confusion with something we once read or overheard?

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 hypothesis 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 u...

There’s a certain discipline involved. We can’t just go off shouting “little green men” every time we detect something we don’t at first understand, because we’re going to look mighty silly—

We are not obliged to make up our minds before the evidence is in. It’s permitted not to be sure.

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 judgment until the evidence is in.

Numberless in short are the ways, and sometimes imperceptible, in which the affections color and infect the understanding.

better the hard truth, I say, than the comforting fantasy.

In our time we have less severe standards. We tell children about Santa Claus, the Easter Bunny, and the Tooth Fairy for reasons we think emotionally sound, but then disabuse them of these myths before they’re grown. Why retract? Because their well-being as adults depends on them knowing the world as it really is. We worry, and for good reason, about adults who still believe in Santa Claus.

Arguments from authority carry little weight—“authorities” have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts.

absence of evidence is not evidence of absence.

Attribute the declining life expectancy in the former Soviet Union to the failures of communism many years ago, but never attribute the high infant mortality rate in the United States (now highest of the major industrial nations) to the failures of capitalism.

he had no right to believe on such evidence as was before him. He had acquired his belief not by honestly earning it in patient investigation, but by stifling his doubts …

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.

Almost everyone finds this characterization recognizable, and many feel that it describes them perfectly. Small wonder: We are all human.

Like the cold read, if the list is long and broad enough, everyone will have “symptoms.”

These mathematical complexities are compounded by the fact that quantum theory is so resolutely counterintuitive. Common sense is almost useless in approaching it. It’s no good, Richard Feynman once said, asking why it is that way. No one knows why it is that way. That’s just the way it is.

Rational science treats its credit notes as always redeemable on demand, while non-rational authoritarianism regards the demand for the redemption of its paper as a disloyal lack of faith.

It is certainly true that all beliefs and all myths are worthy of a respectful hearing. It is not true that all folk beliefs are equally valid—

The first law is that the historian shall never dare to set down what is false; the second, that he shall never dare to conceal the truth; the third, that there shall be no suspicion in his work of either favoritism or prejudice.

Those who invalidate reason ought seriously to consider whether they argue against reason with or without reason; if with reason, then they establish the principle that they are laboring to dethrone: but if they argue without reason (which, in order to be consistent with themselves they must do), they are out of reach of rational conviction, nor do they deserve a rational argument.

What one of us, even the most brilliant among us, misses, another of us, even someone much less celebrated and capable, may detect and rectify.

We are all flawed and creatures of our times. Is it fair to judge us by the unknown standards of the future?

But censoring knowledge, telling people what they must think, is the aperture to thought police, foolish and incompetent decision-making, and long-term decline.