Debunked! is short and highly readable. It tells good stories about human foolishness masquerading as science. It offers useful assistance to citizens trying to tell the difference between sense and nonsense. When it was published in France,* the title was Devenez sorciers, devenez savants, which means literally, “Become magicians, become experts,” or more freely translated, “Learn to do magic and learn to see through it.” The English title misses the point. The book is saying that the best way to avoid being deceived by magic tricks is to learn to do the tricks yourself.

The translator is a medical school faculty member who has written books about probability theory for doctors designing clinical trials. His knowledge of French language and culture was acquired from his family. He has added a preface explaining how he dealt with the problems of translation. He says, “Very long sentences in a distinctive, glorious Gallic rhetorical style have been reduced in frequency by rewriting but not eliminated completely…. I opted for intelligibility rather than the unalloyed preservation of style.” Few of his sentences are painfully long, and none are unintelligible. What remains of the distinctive Gallic rhetorical style is to be found in some passages where the authors express a lofty contempt for those who disagree with them. “Is it acceptable,” they ask, “that university colleagues, due to laziness, lack of rigor, lack of competence, or love of media attention, should go along with a pack of errors, untruths, nonsense, or lies, and label it an honorable point of view?” The translator has retained enough of the elegant style to give us the flavor of the French original. But the polemical passages are few. The greater part of the book is straight storytelling. The stories are well told and are allowed to speak for themselves.

The name of Georges Charpak brings back memories of fifty years ago, when I was living on the side of a mountain above the village of Les Houches, in the high alpine region of France close to Mont Blanc. I was teaching physics at the Les Houches Summer School, an institution that was then three years old and is now still flourishing. It was founded by Cécile DeWitt, who was then a young postdoctoral student, with the avowed purpose of rejuvenating French physics. Cécile is no longer running the school, but she is still very much alive and helping to keep the enterprise going. In 1951, when she founded the school, theoretical physics in France was at a low ebb, with academic jobs in the leading universities monopolized by old men out of touch with new developments. Cécile raised her own meager funds and built her school in a faraway corner of France, out of reach of the mandarins in Paris. She bought an abandoned farm and made the buildings more or less habitable as best she could. Students flocked to the school from all over Europe. The class of students that I taught that summer were the best I ever had. Many of them later became famous as scientific leaders in their own countries. The brightest of all was Georges Charpak.

We lived together in a cowshed and the students listened to lectures in a barn. I gave a tough course with the title Advanced Quantum Mechanics. I worked hard teaching and the students worked hard learning. But the formal lectures were the least important part of the school. Much more memorable were the informal sessions, the meals and the hikes, the daily hardships of mud and rain that we all shared. In a few short years the school became a prime mover of the renaissance of physics, not only in France but all over Europe. It has continued to be a cen-ter of excellence, bringing together gifted young people and giving them the opportunity to work together and learn together, creating friendships that last a lifetime. The cowsheds have long ago been replaced by solid permanent buildings, the muddy farmyard by a terrace ornamented with modern sculpture. In the year 1954 when I was at Les Houches, all of us, Cécile and the lecturers and the students, were young. We were intoxicated with joie de vivre. We were Europeans, we had survived the war and the dismal years of impoverishment that followed it, and now we finally saw Europe rising from the ashes and rebuilding itself. Les Houches was a visible symbol of the rebuilding, which was spiritual as well as physical. We knew we were lucky to be a part of it.

Somewhere on the farm, Georges Charpak found an old skull of a bull with horns attached, and he liked to wear these horns on his head. The horns fitted well with his bull-like physique and character. I have a vivid memory of Georges roaring around a muddy field with the horns, pretending to be a bull. His newly wed wife Dominique, armed with a long spoon from the school kitchen, was pretending to be a matador. For most of his life, Georges has been a leader of experiments at CERN, the European Centre for Nuclear Research, on the border between France and Switzerland. CERN is not far from Les Houches and is another symbol of the scientific rejuvenation of Europe. It came as no surprise in 1992 when I heard that Georges was the first of our students to win a Nobel Prize for physics. It comes as no surprise to meet him again in this book, fighting fiercely against the enemies of scientific reason.


Henri Broch, the second author of this book, is a professor of physics at the University of Nice. He is not as famous as Charpak as a physicist, but he is famous as an investigator of paranormal phenomena such as extrasensory perception and telepathy. He has investigated many claims of people who believe that they possess paranormal powers. His success in demolishing paranormal claims is owing to his skill as a magician. He has mastered the art of doing magical tricks, so that he can reproduce the alleg-edly paranormal phenomena in public demonstrations.

Henri Broch plays the same role in France that the Amazing Randi plays in America. Like Broch, the Amazing Randi is a skilled magician. He challenges any possessor of psychic powers to perform wonders that he cannot duplicate. I once participated in a session in San Diego at which the Amazing Randi confronted the famous Israeli spoon-bender Uri Geller. Geller gave a public performance at which he bent metal objects such as spoons and keys without touching them, using his psychic powers. To make his performances more impressive, he used the word “telekinesis” to describe what ordinary people call spoon-bending. The session was conducted in a big public auditorium, and a large crowd came. I took my family along to see the show.

Following his usual routine, Geller invited volunteers from the audience to come up on stage, bringing spoons or keys with them. My daughter Emily, then twelve years old, volunteered and went up with an old key that we had brought with us. The key was no longer in use, and we did not mind if Geller succeeded in bending it. Geller examined the key carefully and handed it back to Emily, telling her to hold on to it and not let go. Then he chatted with the audience about telekinesis. He described to us how the atoms in the key were rearranging themselves in response to his psychic powers, while Emily stood waiting on the stage. Then he turned suddenly to Emily and said, “Now, let’s look at your key.” She handed him the key, and there it was, bent. He gave it back to her, and she came down to show it to the audience. She said she could have sworn that she was watching the key the whole time and never let it out of her sight. After that, Geller continued with other volunteers, bending various other objects. Then Geller departed and Randi’s performance began.

Randi went through the same rituals as Geller and was equally successful. A succession of volunteers went up on stage, and came down as mystified as Emily had been. Then Randi explained how he did it. The actual bending of the key was the easy part. He bent it with one hand, inserting the tip into a hole in a second key and squeezing the two keys together. This was done while he was chatting with the audience about psychic powers. The more difficult part of the trick was the exchange of keys. The exchange had to be done twice. At the beginning when the volunteer first handed him the key, and at the end when he gave it back to her, he quickly exchanged her key for a similar key that he had hidden in his hand. Each time he made the exchange, he distracted her attention and the attention of the audience with a loud remark or a sudden movement of the other hand. The essential skill of the magician is the ability to distract attention at the moment when the trickery is done. Emily said that if she had not seen Randi’s demonstration she would not have believed that she could be so easily deceived. After Randi had reproduced all of Geller’s tricks and explained how they were done, he entertained the audience with a number of even more amazing tricks which he did not explain.

Henri Broch describes, in a section of the book entitled “Practice Telepathy,” a splendid demonstration of his ability to send information telepathically to an accomplice a few miles away. The demonstration is made in a private house where a group of friends, in no way involved in the trickery, are gathered. First Broch invites the group to provide a deck of cards, to shuffle them thoroughly, and to pick a card at random. Broch sits in the room while this is done, so it is obvious that he could have had no influence on the picking of the card, and no prior knowledge of which card would be picked. Let us suppose that the five of clubs is picked. Broch then glances at an address book that he carries in his pocket, writes down the name and telephone number of the accomplice on a piece of paper, and asks the friends to choose a representative who goes to another room to call the number. While the call is made, Broch sits in his chair gazing at the card with a look of intense concentration, groaning with the effort of exercising his telepathic powers. The accomplice answers the phone and says, “We have several brothers living here, which of us do you want to talk to?” So the friend gives the name and the accomplice says, “Speaking.” The friend explains that a card has been picked and that Broch is trying to transmit the image of the card telepathically. After a suitable pause for dramatic effect, the accomplice says, “The card you picked is the five of clubs,” and the friend rushes back to tell Broch and the rest of the assembled company that the message has got through.


Hardly anyone who witnesses this performance and is not an expert magician can see through it. To the uninitiated it looks like good solid scientific evidence for telepathy. The essential clue, which almost everyone misses, is the address book that Broch glances at before writing down the name of the accomplice. The address book contains a list of the 53 cards in a standard deck, each paired with a common French first name. The accomplice has another copy of the same list. As soon as the accomplice hears the name, he knows the card.

The book also has a good chapter on “Amazing Coincidences.” These are strange events which appear to give evidence of supernatural influences operating in everyday life. They are not the result of deliberate fraud or trickery, but only of the laws of probability. The paradoxical feature of the laws of probability is that they make unlikely events happen unexpectedly often. A simple way to state the paradox is Littlewood’s Law of Miracles. Littlewood was a famous mathematician who was teaching at Cambridge University when I was a student. Being a professional mathematician, he defined miracles precisely before stating his law about them. He defined a miracle as an event that has special significance when it occurs, but oc-curs with a probability of one in a million. This definition agrees with our common-sense understanding of the word “miracle.”

Littlewood’s Law of Miracles states that in the course of any normal person’s life, miracles happen at a rate of roughly one per month. The proof of the law is simple. During the time that we are awake and actively engaged in living our lives, roughly for eight hours each day, we see and hear things happening at a rate of about one per second. So the total number of events that happen to us is about thirty thousand per day, or about a million per month. With few exceptions, these events are not miracles because they are insignificant. The chance of a miracle is about one per million events. Therefore we should expect about one miracle to happen, on the average, every month. Broch tells stories of some amazing coincidences that happened to him and his friends, all of them easily explained as consequences of Littlewood’s Law.

A large number of people calling themselves parapsychologists have tried to study paranormal phenomena using rigorous scientific methods. Their favorite tool is a little deck of twenty-five cards, with one of five symbols on each card. The five symbols are squares, circles, stars, crosses, and squiggles. An ideal telepathy experiment is done with two people, the sender and the receiver, sitting in separate rooms, with careful controls to eliminate all possibility of communication between the two of them or between them and the experimenter. The sender and the receiver synchronize their activities with accurate clocks. At fixed times agreed in advance, the sender picks cards from a well-shuffled deck, gazes at them one at a time, and records the sequence of cards gazed at. At the same times, the receiver guesses the cards and records the sequence of guesses. At the end of the experiment, an impartial witness, not the experimenter, compares the two records and finds the percentage of correct guesses. If telepathy is not operating, the percentage should be close to twenty. If the percentage is persistently higher than twenty, the experimenter may claim to have found evidence for telepathy.

If this idealized picture of a telepathy experiment were real, we should long ago have been able to decide whether telepathy exists or not. In the real world, the way such experiments are done is very different, as I know from personal experience. When I was a teenager long ago, parapsychology was fashionable. I bought a deck of parapsychology cards and did card-guessing experiments with my friends. We spent long hours, taking turns at gazing and guessing cards. Unlike Henri Broch, we were strongly motivated to find positive evidence of telepathy. We considered it likely that telepathy existed and we wanted to prove ourselves to be telepathically gifted. When we started our sessions, we achieved some spectacularly high percentages of correct guesses. Then, as time went on, the percentages declined toward twenty and our enthusiasm dwindled. After a few months of sporadic efforts, we put the cards away and forgot about them.

Looking back on our experience with the cards, we came to understand that there are three formidable obstacles to any scientific study of telepathy. The first obstacle is boredom. The experiments are insufferably boring. In the end we gave up because we could not stand the boredom of sitting and guessing cards for hours on end. The second obstacle is inadequate controls. We never even tried to impose rigorous controls on communication between sender and receiver. Without such controls, our results were scientifically worthless. But any serious system of controls, stopping us from chatting and joking while we were gazing and guessing, would have made the experiments even more insufferably boring.

The third obstacle is biased sampling. The results of such experiments depend crucially on when you decide to stop. If you decide to stop after the initial spectacularly high percentages, the results are strongly positive. If you decide to stop when you are almost dying of boredom, the results are strongly negative. The only way to obtain unbiased results is to decide in advance when to stop, and this we had not done. We were not disciplined enough to make a decision in advance to do ten thousand guesses and then stop, regardless of the percentage of correct guesses that we might have achieved. We did not succeed in overcoming a single one of the three obstacles. To reach any scientifically credible conclusions, we would have needed to overcome all three.

The history of the card-guessing experiments, carried out initially by Joseph Rhine at Duke University and later by many other groups following Rhine’s methods, is a sorry story. A number of experiments that claimed positive results were later proved to be fraudulent. Those that were not fraudulent were plagued by the same three obstacles that frustrated our efforts. It is difficult, expensive, and tedious to impose controls rigorous enough to eliminate the possibility of fraud. And even after such controls have been imposed, the conclusions of a series of experiments can be strongly biased by selective reporting of the results. Littlewood’s Law applies to experimental results as well as to the events of daily life. A session with a noticeably high percentage of correct guesses is a miracle according to Littlewood’s definition. If a large number of experiments are done by various groups under various conditions, miracles will occasionally occur. If miracles are selectively reported, they are experimentally indistinguishable from real occurrences of telepathy.

Charpak and Broch see the modern growth of astrology and other pseudosciences as a rising menace that they are called upon to fight to the death. They are horrified by the prevalence of unscientific thinking among students in France today. They sum up their response to these irrationalities in another elegant Gallic sentence: “The question is inescapable: Isn’t scientific thought the indispensible companion to wisdom, to clear thinking, and to the love of those virtues, which is expressed not only in vain incantations to the sky but also in logical actions?” They have here touched on a question which goes to the heart of the matter. What are the proper limits of science?

There are two extreme points of view concerning the role of science in human understanding. At one extreme is the reductionist view, holding that all kinds of knowledge, from physics and chemistry to psychology and philosophy and sociology and history and ethics and religion, can be reduced to science. Whatever cannot be reduced to science is not knowledge. The reductionist view was forcibly expressed by Edward Wilson in his recent book Consilience. At the other extreme is the traditional view, that knowledge comes from many independent sources, and science is only one of them. Knowledge of good and evil, knowledge of grace and beauty, knowledge of ethical and artistic values, knowledge of human nature derived from history and literature or from intimate acquaintance with family and friends, knowledge of the nature of things derived from meditation or from religion, all are sources of knowledge that stand side by side with science, parts of a human heritage that is older than science and perhaps more enduring. Most people hold views intermediate between the two extremes. Charpak and Broch are close to the reductionist extreme, while I am close to the traditional extreme.

The question of the proper limits of science has a strong connection with the possible existence of paranormal phenomena. Charpak and Broch and I agree that attempts to study extrasensory perception and telepathy using the methods of science have failed. Charpak and Broch say that since extrasensory perception and telepathy cannot be studied scientifically, they do not exist. Their conclusion is clear and logical, but I do not accept it because I am not a reductionist. I claim that paranormal phenomena may really exist but may not be accessible to scientific investigation. This is a hypothesis. I am not saying that it is true, only that it is tenable, and to my mind plausible.

The hypothesis that paranormal phenomena are real but lie outside the limits of science is supported by a great mass of evidence. The evidence has been collected by the Society for Psychical Research in Britain and by similar organizations in other countries. The journal of the London society is full of stories of remarkable events in which ordinary people appear to possess paranormal abilities. The evidence is entirely anecdotal. It has nothing to do with science, since it cannot be reproduced under controlled conditions. But the evidence is there. The members of the society took great trouble to interview first-hand witnesses as soon as possible after the events, and to document the stories carefully. One fact that emerges clearly from the stories is that paranormal events occur, if they occur at all, only when people are under stress and experiencing strong emotion. This fact would immediately explain why paranormal phenomena are not observable under the conditions of a well-controlled scientific experiment. Strong emotion and stress are inherently incompatible with controlled scientific procedures. In a typical card-guessing experiment, the participants may begin the session in a high state of excitement and record a few high scores, but as the hours pass, and boredom replaces excitement, the scores decline to the 20 percent expected from random chance.

I am suggesting that paranormal mental abilities and scientific method may be complementary. The word “complementary” is a technical term introduced into physics by Niels Bohr. It means that two descriptions of nature may both be valid but cannot be observed simultaneously. The classic example of complementarity is the dual nature of light. In one experiment light is seen to behave as a continuous wave, in another experiment it behaves as a swarm of particles, but we cannot see the wave and the particles in the same experiment. Complementarity in physics is an established fact. The extension of the idea of complementarity to mental phenomena is pure speculation. But I find it plausible that a world of mental phenomena should exist, too fluid and evanescent to be grasped with the cumbersome tools of science.

I should here declare my personal interest in the matter. One of my grandmothers was a notorious and successful faith healer. One of my cousins was for many years the editor of the Journal of the Society for Psychical Research. Both these ladies were well educated, highly intelligent, and fervent believers in paranormal phenomena. They may have been deluded, but neither of them was a fool. Their beliefs were based on personal experience and careful scrutiny of evidence. Nothing that they believed was incompatible with science.

Whether paranormal phenomena exist or not, the evidence for their existence is corrupted by a vast amount of nonsense and outright fraud. Before we can begin to evaluate the evidence, we must get rid of the hucksters and charlatans who have turned unsolved mysteries into a profitable business. Charpak and Broch have done a fine job, sweeping out the money-changers from the temple of science and exposing their tricks. I recommend this book to believers and skeptics alike. It is good entertainment, whether or not you believe in astrology.

This Issue

March 25, 2004