Free Broca's Brain by Carl Sagan Page B

explanation by coincidence.
    After my experience I did not write a letter to an institute of parapsychology relating a compelling predictive dream which was not borne out by reality. That is not a memorable letter. But had the death I dreamt actually occurred, such a letter would have been marked down as evidence for precognition. The hits are recorded, the misses are not. Thus human nature unconsciously conspires to produce a biased reporting of the frequency of such events.
    THESE CASES —Alexander the Oracle-Monger, Keene, astral projection, the Fox sisters, the Cardiff Giant, Clever Hans and precognitive dreams—are typical of claims made on the boundary or edge of science. Anamazing assertion is made, something out of the ordinary, marvelous or awesome—or at least not tedious. It survives superficial scrutiny by lay people and, sometimes, more detailed study and more impressive endorsement by celebrities and scientists. Those who accept the validity of the assertion resist all attempts at conventional explanation. The most common correct explanations are of two sorts. One is conscious fraud, usually by those with a financial interest in the outcome, as with the Fox sisters and the Cardiff Giant. Those who accept the phenomena have been bamboozled. The other explanation often applies when the phenomena are uncommonly subtle and complex, when nature is more intricate than we have guessed, when deeper study is required for understanding; Clever Hans and many precognitive dreams fit this second explanation. Here, very often, we bamboozle ourselves.
    I have chosen the foregoing cases for another reason. They are all closely involved with everyday life—human or animal behavior, evaluating the reliability of evidence, occasions for the exercise of common sense. None of these cases involve technological complexities or arcane theoretical developments. We do not need an advanced degree in physics, let us say, to have our skeptical hackles rise at the pretensions of modern spiritualists. Nevertheless, these hoaxes, impostures and misapprehensions have captivated millions. How much more dangerous and difficult to assess must be borderline claims at the edge of less familiar sciences—about cloning, say, or cosmic catastrophes or lost continents or unidentified flying objects?
    I make a distinction between those who perpetrate and promote borderline belief systems and those who accept them. The latter are often taken by the novelty of the systems, and the feeling of insight and grandeur they provide. These are in fact scientific attitudes and scientific goals. It is easy to imagine extraterrestrial visitors who looked like human beings, and flew space vehicles and even airplanes like our own, and taught our ancestors civilization. This does not strain our imaginative powers overly and is sufficiently similar tofamiliar Western religious stories to seem comfortable. The search for Martian microbes of exotic biochemistry, or for interstellar radio messages from intelligent beings biologically very dissimilar is more difficult to grasp and not as comforting. The former view is widely purveyed and available; the latter much less so. Yet I think many of those excited by the idea of ancient astronauts are motivated by sincere scientific (and occasionally religious) feelings. There is a vast untapped popular interest in the deepest scientific questions. 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.
    Advocates of ancient astronauts—the most notable being Erich von Däniken in his book
Chariots of the Gods?
—assert that there are numerous pieces of archaeological evidence that can be