from 1995 The Demon-Haunted World:
Carl Sagan’s “Baloney Detection Kit”
What’s in the kit? Tools for skeptical thinking. 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 conclusion follows from the premise or starting point and whether that premise is true. Among the tools: ¶ Wherever possible there must be independent confirmation of the “facts.” ¶ Encourage substantive debate on the evidence by knowledgeable proponents of all points of view. ¶ 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.
¶ 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. [This is a problem that affects jury trials. Retrospective studies show that some jurors make up their minds very early—perhaps during opening arguments—and then retain the evidence that seems to support their initial impressions and reject the contrary evidence. The method of alternative working hypotheses is not running in their heads.]
¶ Try not to get overly attached to a hypothesis just because it’s yours. It’s only a way station in the
pursuit of knowledge. Ask yourself why you like the idea. Compare it fairly with the alternatives. See if you can find reasons for rejecting it. If you don’t, others will.
¶ 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. Of course there are truths to be sought in the many qualitative issues we are obliged to confront, but finding them ismore challenging.
¶ If there’s a chain of argument, every link in the chain must work (including the premise)—not just
¶ 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.
¶ Always ask whether the hypothesis can be, at least in principle, falsified. Propositions that are
untestable, unfalsifiable are not worth much. Consider the grand idea that our Universe and everything in it is just an elementary particle—an electron, say—in a much bigger Cosmos. But if we can never acquire information from outside our Universe, is not the idea incapable of disproof? You must be able to check assertions out. Inveterate skeptics must be given the chance to follow your reasoning, to duplicate your experiments and see if they get the same result.
The reliance on carefully designed and controlled experiments is key. We will not learn much from
mere contemplation. It is tempting to rest content with the first candidate explanation we can think of. One is much better than none. But what happens if we can invent several? How do we decide among them? We don’t. We let experiment do it. Francis Bacon provided the classic reason:
Argumentation cannot suffice for the discovery of new work, since the subtlety of Nature is greater many times than the subtlety of argument.
Control experiments are essential. If, for example, a new medicine is alleged to cure a disease 20 percent of the time, we must make sure that a control population, taking a dummy sugar pill which as far as the subjects know might be the new drug, does not also experience spontaneous remission of the disease 20 percent of the time. Variables must be separated. Suppose you’re seasick, and given both an acupressure bracelet and 50 milligrams of meclizine. You find the unpleasantness vanishes. What did it—the bracelet or the pill? You can tell only if you take the one without the other, next time you’re seasick. Now imagine that you’re not so dedicated to science as to be willing to be seasick. Then you won’t separate the variables. You’ll take both remedies again. You’ve achieved the desired practical result; further knowledge, you might say, is not worth the discomfort of attaining it.
Often the experiment must be done “double-blind,” so that those hoping for a certain finding are
not in the potentially compromising position of evaluating the results. In testing a new medicine, for example, you might want the physicians who determine which patients’ symptoms are relieved not to know which patients have been given the new drug. The knowledge might influence their decision, even if only unconsciously. Instead the list of those who experienced remission of symptoms can be compared with the list of those who got the new drug, each independently ascertained. Then you can determine what correlation exists. Or in conducting a police lineup or photo identification, the officer in charge should not know who the prime suspect is, so as not consciously or unconsciously to influence the witness. In addition to teaching us what to do when evaluating a claim to knowledge, any good baloney detection kit must also teach us what not to do. It helps us recognize the most common and perilous fallacies of logic and rhetoric. Many good examples can be found in religion and politics, because their practitioners are so often obliged to justify two contradictory propositions. Among these fallacies are: ¶ ad hominem—Latin for “to the man,” attacking the arguer and not the argument (e.g., The Reverend Dr. Smith is a known Biblical fundamentalist, so her objections to evolution need not be taken seriously);
¶ argument from authority (e.g., President Richard Nixon should be re-elected because he has a secret plan to end the war in Southeast Asia—but because it was secret, there was no way for the electorate to evaluate it on its merits; the argument amounted to trusting him because he was President: a mistake, as it turned out);
¶ argument from adverse consequences (e.g., A God meting out punishment and reward must exist, because if He didn’t, society would be much more lawless and dangerous—perhaps even ungovernable. [A more cynical formulation by the Roman historian Polybius: “Since the masses of the people are inconstant, full of unruly desires, passionate, and reckless of consequences, they must be filled with fears to keep them in order. The ancients did well, therefore, to invent gods, and the belief in punishment after death.”] Or: The defendant in a widely publicized murder trial must be found guilty; otherwise, it will be an encouragement for other men to murder their wives);
¶ appeal to ignorance—the claim that whatever has not been proved false must be true, and vice
versa (e.g., There is no compelling evidence that UFOs are not visiting the Earth; therefore UFOs exist—and there is intelligent life elsewhere in the Universe. Or: There may be seventy kazillion other worlds, but not one is known to have the moral advancement of the Earth, so we’re still central to the Universe.) This impatience with ambiguity can be criticized in the phrase: absence of evidence is not evidence of absence.
¶ special pleading, often to rescue a proposition in deep rhetorical trouble (e.g., How can a merciful God condemn future generations to torment because, against orders, one woman induced one man to eat an tipple? Special plead: you don’t understand the subtle Doctrine of Free Will. Or: How can there be an equally godlike Father, Son, and Holy Ghost in the same Person? Special plead: You don’t understand the Divine Mystery of the Trinity. Or: How could God permit the followers of Judaism, Christianity, and Islam—each in their own way enjoined to heroic measures of loving kindness and compassion—to have perpetrated so much cruelty for so long? Special plead: You don’t understand Free Will again. And anyway, God moves in mysterious ways.)
¶ begging the question, also called assuming the answer (e.g., We must institute the death penalty to discourage violent crime. But does the violent crime rate in fact fall when the death penalty is imposed? Or: The stock market fell yesterday because of a technical adjustment and profit-taking by investors—but is there any independent evidence for the causal role of “adjustment” and profit- taking; have we learned anything at all from this purported explanation?);
¶ observational selection, also called the enumeration of favorable circumstances, or as the
philosopher Francis Bacon described it, counting the hits and forgetting the masses (e.g., A state boasts of the Presidents it has produced, but is silent on its serial killers);
¶ statistics of small numbers—a close relative of observational selection (e.g., “They say 1 out of every 5 people is Chinese. How is this possible? I know hundreds of people, and none of them is Chinese. Yours truly.” Or: “I’ve thrown three sevens in a row. Tonight I can’t lose.”);
¶ misunderstanding of the nature of statistics (e.g., President Dwight Eisenhower expressing astonishment and alarm on discovering that fully half of all Americans have below average intelligence);
¶ inconsistency (e.g., Prudently plan for the worst of which a potential military adversary is capable, but thriftily ignore scientific projections on environmental dangers because they’re not “proved.” Or: 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. Or: Consider it reasonable for the Universe to continue to exist forever into the future, but judge absurd the possibility that it has infinite duration into the past);
¶ non sequitur—Latin for “It doesn’t follow” (e.g., Our nation will prevail because God is great. But nearly every nation pretends this to be true; the German formulation was “Gott mit uns”). Often those falling into the non sequitur fallacy have simply failed to recognize alternative possibilities;
¶ post hoc, ergo propter hoc—Latin for “It happened after, so it was caused by” (e.g., Jaime Cardinal
Sin, Archbishop of Manila: “I know of . . . a 26-year-old who looks 60 because she takes [contraceptive] pills.” Or: Before women got the vote, there were no nuclear weapons);
¶ meaningless question (e.g., What happens when an irresistible force meets an immovable object?
But if there is such a thing as an irresistible force there can be no immovable objects, and vice versa);
¶ excluded middle, or false dichotomy—considering only the two extremes in a continuum of
intermediate possibilities (e.g., “Sure, take his side; my husband’s perfect; I’m always wrong.” Or: “Either you love your country or you hate it.” Or: “If you’re not part of the solution, you’re part of the problem”);
¶ short-term vs. long-term—a subset of the excluded middle, but so important I’ve pulled it out for
special attention (e.g., We can’t afford programs to feed malnourished children and educate pre- school kids. We need to urgently deal with crime on the streets. Or: Why explore space or pursue fundamental science when we have so huge a budget deficit?);
¶ slippery slope, related to excluded middle (e.g., If we allow abortion in the first weeks of pregnancy, it will be impossible to prevent the killing of a full-term infant. Or, conversely: If the state prohibits abortion even in the ninth month, it will soon be telling us what to do with our bodies around the time of conception);
¶ confusion of correlation and causation (e.g., A survey shows that more college graduates are homosexual than those with lesser education; therefore education makes people gay. Or: Andean earthquakes are correlated with closest approaches of the planet Uranus; therefore—despite the absence of any such correlation for the nearer, more massive planet Jupiter—the latter causes the former );
¶ straw man—caricaturing a position to make it easier to attack (e.g., Scientists suppose that living things simply fell together by chance—a formulation that willfully ignores the central Darwinian insight, that Nature ratchets up by saving what works and discarding what doesn’t. Or—this is also
a short-term/long-term fallacy—environmentalists care more for snail darters and spotted owls than they do for people);
¶ suppressed evidence, or half-truths (e.g., An amazingly accurate and widely quoted “prophecy” of the assassination attempt on President Reagan is shown on television; but—an important detail—was it recorded before or after the event? Or: These government abuses demand revolution, even if you can’t make an omelet without breaking some eggs. Yes, but is this likely to be a revolution in which far more people are killed than under the previous regime? What does the experience of other revolutions suggest? Are all revolutions against oppressive regimes desirable and in the interests of the people?);
¶ weasel words (e.g., The separation of powers of the U.S. Constitution specifies that the United
States may not conduct a war without a declaration by Congress. On the other hand, Presidents are given control of foreign policy and the conduct of wars, which are potentially powerful tools for getting themselves re-elected. Presidents of either political party may therefore be tempted to arrange wars while waving the flag and calling the wars something else—”police actions,” “armed incursions,” “protective reaction strikes,” “pacification,” “safeguarding American interests,” and a wide variety of “operations,” such as “Operation Just Cause.” Euphemisms for war are one of a broad class of reinventions of language for political purposes. Talleyrand said, “An important art of politicians is to find new names for institutions which under old names have become odious to the public”).
R OTARY CLUB of ALO ALTO.CALIF. tary Pini n PRESIDENT: Sara Pantin.PRESIDENT-ELECT: Le Levy.PAST-PRESIDENT: John Kidd DIRECTORS: Annette Glanckopf, Iris Korol, Pam Brandin, Hal Mickelson, Nick Nichols, Rick Tipton TREASURER: Dick Carlson.SECRETARIES: Dick Freeman.Bob McCowan. Sandra Wallace . CLUB RECORDS: Joyce Cusick, [email protected]. MAIL: P.O. Box 592,
Conducted at the Center for Experimental and Applied Skin Physiology and Clinical Research Center for Hair and Skin Physiology of the University Clinic Effectiveness Study Tests regarding the penetration of caffeine from a shampoo formula Following successful tests at the University of Jena on the hair organ culture model regarding the effi cacy of caff eine as a hair growt