Facts fail to banish spirits, wholly

After two abortive (and rather public) attempts to make him an ordinary member, the National Academy of Sciences of the United States instead awarded Carl Sagan its Public Welfare Medal in 1994, the highest honour it can bestow. This carries most of the privileges of membership without having to pay the dues. This was one of the rare occasions in that august institution's history when justice was both done and seen to be done, as should be obvious to the reader of this excellent book.

To the distinction of being perhaps the most successful populariser of science in our time, Sagan adds a sharply critical philosophical and historical intelligence that gives him a clear view of the nature of science and its relation to the cultural context in which it operates. It is this second facet of his interests that is the focus of the present book.

Perhaps central to the book is an in-depth discussion of pseudoscience, superstition and antiscience over the ages, with a focus on Sagan's own contacts with UFO and alien abduction enthusiasts, but with intriguing detours into such subjects as the chilling history of the witchcraft trials of early modern Europe (we learn that the last execution was in Poland in 1793), the great "crop circle" hoax in England, and the rise and fall of Lysenkoism in the Soviet Union. He is particularly convincing on the psychological similarities between ancient beliefs in demonic possession, their later manifestations in belief in witchcraft, and the modern phenomenon of "alien abduction", implying the same background in hallucinations, suggestion and realistic dreaming. It is an ironic twist that for so many people science merely serves as a new way to dress up hallucinatory fantasies in terms of aliens rather than witches, warlocks and demons.

The crop circle story comes as welcome comic relief: two blokes at a pub called the "Percy Hobbes" dreamt up the scheme over several pints and put it into action in a local wheat field that very night with ropes and a log; they quit, and finally confessed, 16 years later when they turned 60, having inspired reams of utter superstitious nonsense, a legion of copycat hoaxers and even official reports to the royal family. Very effective also is a chapter full of responses from the public to some of his writings on the "alien" phenomena.

On the factual substrate of these studies Sagan builds an eloquent plea for better science education and for more enlightened treatment of science and pseudoscience in the media. He argues that science and democracy are closely related and mutually reinforcing; that science in its pragmatism and its enlightened scepticism is a mode of thought that becomes increasingly essential to survival in a society that is also becoming more and more complex and technological.

Sagan argues that students are taught science too little and too late, that more often than not what science they get is memorisation drudgery and that the domination of teaching by education theorists abets the disaffection with science among teenagers. Almost the only bright spot is the movement towards "science centers" and exploratoriums in the US.

His criticism of the media is harsh, specific and thoroughly justified. The popular media is dominated Q even glutted Q by reports on the paranormal and the pseudoscientific. There are ten columns on astrology for every one on science. But even the respectable media, the BBC, the networks in the US, the major dailies, the news magazines, are biased in favour of the lunatic fringe and of the sensation-hunters. Sagan, as a founding member of the Committee for Scientific Investigation of Claims of the Paranormal and a regular contributor to its magazine, the Skeptical Inquirer, is very familiar with this problem. The amount of media attention given to the minute fraction of scientists who support claims of the paranormal is overwhelmingly disproportionate to their importance in science itself, not to mention the marginal-to-zero product of their efforts. It is wonderful that Sagan and his small band of compatriots are willing to take on the thankless task of leading this battle.

Even a recent report on the new science of consciousness in this very journal felt it necessary to drag in, seemingly by the heels, the subject of extrasensory perception, which is by no means any part of the recent scientific growth of interest in the subject. Yet another recent example was the extensive publicity given by the BBC to the science-fiction writer, Arthur C. Clarke, and his "prediction" that cold fusion would solve the world's energy problem. With Lysenkoism, cold fusion is a good paradigm for what really happens when we have "socially constructed" science.

An aspect of media treatment Sagan deplores is the image of the scientist who comes across as either a particular sort of nerd or a devious scoundrel. The profession contains both, but on the whole we have more of the public-spirited whistleblowers like Linus Pauling, Andrei Sakharov and Sherry Rowland per capita than any other profession. Sagan rewards the reader with vivid descriptions of both types.

What did I miss in the book? First, despite disclaimers, the image of the scientist was a bit too good to be credible. To me the most convincing lesson of the history of science is to see truth prevail in spite of the venality or stupidity of individual scientists; to read the stories of such as Ros Yalow, Ray Dart or Barbara McClintock winning in the end over prejudice and inertia. Second, although Sagan has some interesting insights into the reasons for the human preference for magic and mystification, I found it hard to credit how optimistic he is that the human animal can be totally rational. For most of our species' history gulliblilty on these matters must have been a survival characteristic. Somehow, science's enlightened scepticism must learn to live with, rather than to eliminate the magical and, for better or for worse, our minds seem to be sufficiently irrational to do just that.

Third, one aspect of the scientists' epistemology was underestimated: consistency. All too few laymen appreciate the degree to which the advancement of science has meant that almost every branch of science Q every new discovery Q both leans on and supports every other one. For instance, our understanding of the very composition of the rocks of which earth is made requires information from radioactivity, the time scale of evolution, plate tectonics, celestial mechanics and Lord knows what else.

Of almost every theory we have it can be said: "If we didn't have it, we'd have to invent it." It is consistency of the total fabric that leaves one with very rigid constraints on what new piece (telekinesis? alien visitors? cold fusion? errant planets a la Velikovsky?) can be added without creating total shambles. This "seamless web" of relationships among the sciences is to me the most beautiful and exciting aspect of modern science, although it is perhaps the hardest to share with the layperson. One of the most disturbing modern trends in academia is an outbreak of antiscientism among philosophers and historians of science under the banner of "social constructivism", a trend Sagan also targets; and the "seamless web" is the strongest answer to such criticisms.

But the scientist or even the academic is clearly not the book's intended reader. Sagan is careful to meet the opposition at least halfway, and probably wisely so. The solution, as he so clearly sees, to the dilemma of the public perception of science is to do, to the best of our capacity, exactly as he has done: to try to express, as clearly and to as wide an audience as possible, exactly what science is and what it can do for the human race.

Philip W. Anderson is professor of physics, Princeton University, and a Nobel laureate.