Musing on the rows of discarded crutches on display at Lourdes, the journalist H.L. Mencken observed that no wooden legs were in evidence. Why, one might ask, has this paradox not presented itself to the faithful? Mencken also remarked that faith could be defined as an illogical belief in the occurrence of the improbable.

Shermer, who has engaged in public debates on the Holocaust, has been scrupulous in meeting political rhetoric with dispassionate reason, and has, by his own account, got the better of his adversaries. He sets out in meticulous detail the historic evidence that should scotch the dialectic of the noisy lunatic fringe, but of course this is not how the world wags.

Shermer sees himself as a champion of rationality. He holds that the antidote to superstition and unreason is science, or at least the "scientific method." Scientists worthy of the name are free of the rats' nests that infest the brains of the less fortunate. This is pleasing to hear, but wait: Aristotle, the great observer, insisted that women had fewer teeth than men, and though, as Bertrand Russell indignantly pointed out, he was twice married, he never thought to verify his hypothesis by inspection. Elie Metchnikoff, one of the founders of the science of immunology, believed that ageing was engendered by toxins from gut bacteria and that yogurt, being rich in lactobacillus, was thus the elixir of youth. Or then again, two of the most illustrious physicists of the late nineteenth century, Sirs Oliver Lodge and William Crookes (who gave us the cathode-ray tube), habitually communicated with "the other side" through mediums. And Francis Galton took it for granted that both intelligence and criminality were inherited, and urged eugenic measures to promote the one and suppress the other.

Still, Shermer is worth reading for the gruesome examples of credulity and intellectual contortion that he lays bare. Take, for example, the "recovered memory syndrome," invented by psychiatrists (the witchfinders of our day), who have estimated that one third to one half of American women were sexually abused in childhood. There is a good account of the cliff-hanger in the U.S. Supreme Court, when 72 Nobel laureates and some other luminaries challenged the constitutional validity of a law enacted by the State of Louisiana, decreeing equal and parallel treatment of evolution and creationism in schools. There is a brisk analysis of the race-and-intelligence debate, and an absorbing tale of the bizarre cult that gathered around the novelist Ayn Rand, described by one of her followers as "the greatest human being who has ever lived."

Shermer is more labored and less incisive than (among many others) Bertrand Russell in his numerous essays. Nor does he answer the question of the title. The Flat Earth Society still thrives, and I do not doubt that many people believe that garbage is collected twice a week by the leprechauns and that the moon is the repository of broken vows and unfulfilled desires (which, as we now know, is not the case). These propositions differ little from the conclusion (dressed up in the language of science) of Arthur Koestler and Sir Alastair Hardy, Latterly Professor of Zoology at Oxford, that life's coincidences had supernatural origins.

Dr. Johnson said that wonders are willingly told and willingly heard, and so the majestic dictum of eighteenth century philosopher David Hume, which Shermer quotes with approval - that "no testimony is sufficient to establish a miracle unless the testimony be of such a kind, that its falsehood would be more miraculous than the fact which it endeavours to establish" - is disregarded. The improbable is just more interesting, and there's an end of it.