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

THERE is a classic story about a scientist who kept a horseshoe over the door to his laboratory. One day one of his colleagues asked him, "You don't seriously believe that thing brings you good luck, do you?"

"Of course not," responded the scientist. "But it seems to work whether you believe in it or not."

I can imagine Carl Sagan commenting on that story. There is a distressing survival of superstition and pseudoscience among people who ought to know better. Even college graduates believe in UFO abductions, crop circles as signals from alien beings, astrology, faith healing, and so on. Often they convince themselves that a superstitious practice "works" because of anecdotal evidence.

In short, many people believe whatever they want to believe, and support their belief with bad reasoning. What such credulous people need, according to Carl Sagan, is a "baloney-detector kit." (The term actually used in scientific circles is more pungent.) A baloney detector is simply a good grasp of logical reasoning and investigative procedure. Thus, Sagan urges us to obtain independent confirmation of facts, to avoid getting overly attached to our own ideas, and to distinguish between falsifiable and unfalsifiable hypotheses.

Critical thinking so defined is obviously desirable in principle; the controversial part is that Sagan applies the detector only to other people's baloney. He mainly picks on easy targets like UFO abductions, faith healers, and New Age spirit guides. No doubt some people need to be told that Dr. John Mack (the Harvard Medical School professor who believes the UFO-abduction reports) is so lacking in judgment that even his fellow Harvard professors were embarrassed enough to spend long committee hours seeking some legally defensible way to get rid of him. The kind of readers who buy 457-page books about scientific reasoning could use something a bit more challenging.

For example, if it is a serious error to confuse correlation with causation, what does Sagan think about the methodology by which the cause of AIDS was determined? (The theory that HIV causes AIDS is based almost entirely on a correlation between antibodies to the virus and death from a variety of previously unrelated ailments, all of which sometimes occur in the absence of HIV infection.) How are citizens to distinguish between scare tactics and genuine science when environmentalists demand that some chemical be banned? The work of Berkeley biochemist Bruce Ames, showing that industrial products attacked as potential carcinogens are frequently less carcinogenic than many naturally occurring chemicals, would have made an excellent case study.

Instead of addressing meaty scientific topics like these, this rambling book is filled with off-hand opinions supported mainly by anecdotal evidence, in flagrant violation of Sagan's own professed standards. When it comes to social programs, for instance, Sagan reasons a lot like that scientist who relied on the horseshoe. He tells us that "recent research shows" that malnutrition causes reduced academic performance, and that federal programs aimed at preventing malnutrition "have been shown to work." No description of the research accompanies these pronouncements.

In an exhibition of credulity that would embarrass Dr. John Mack, Sagan describes a literacy program for children as successful on the basis of subjective judgments by participating parents and teachers about vaguely defined items like "improved self-confidence." The decisive proof of success is that "not one of the children had to repeat any grade in elementary school." There is no mention of control groups or standardized reading tests. And these days what child has to repeat a grade, whether or not he can read?

Sagan wants to convince students that science is exciting, and to that end he favors encouraging them to question everything, because "there is no such thing as a dumb question." It turns out that there is one question that really is too dumb to bother with, however, and that is whether a Creator might have played some role in the history of life. Sagan treats anyone who asks that question with undisguised contempt:

I meet many people who are offended by evolution, who passionately prefer to be the personal handicraft of God than to arise by blind physical and chemical forces over aeons from slime. They also tend to be less than assiduous in exposing themselves to the evidence. Evidence has little to do with it. What they wish to be true, they believe is true. Only 9 per cent of Americans accept the central finding of modern biology that human beings (and all the other species) have slowly evolved by natural processes from a succession of more ancient beings with no divine intervention needed along the way.

Plainly, one thing that is missing from Carl Sagan's baloney-detector kit is a device capable of distinguishing science as a method of investigation from scientific atheism, a philosophy uncritically accepted by many scientists. Have scientific experiments demonstrated that non-living chemicals can arrange themselves spontaneously into living organisms? Does the claim that natural selection can turn a bacterium into a butterfly rest mainly upon an unsupported extrapolation from instances of variation within a species? Perhaps we should consider the alternative hypothesis that it is the dogmatic Darwinists who are less than assiduous in exposing themselves to the evidence, and that the reason so many Americans are skeptical of the more expansive claims of Darwinism is that they have their own baloney detectors working.

Currently, the state Board of Education in Alabama is attempting to encourage critical thinking about evolution by requiring the insertion of a sort of truth-in-advertising notice in biology textbooks. The Alabama statement notes that the textbooks use the term "evolution" in a shifting and hence misleading way, illustrating the process with examples of small-scale variation within the species and then claiming to have demonstrated that purposeless material forces can account for the entire history of life. The statement charges that the books also ignore evidence, particularly fossil evidence, which tends to falsify the orthodox neo-Darwinian theory.

The charges can be supported by voluminous citations from the textbooks and scientific literature, but the Carl Sagans of scientific atheism are not likely to give them a fair hearing. When the common people start getting skeptical about the wrong things, it's time to take their baloney detectors away.