The Demon-Haunted World: Science as a Candle in the Dark - Carl Sagan, Ann Druyan (1997)

Chapter 10. The Dragon in My Garage

[M]agic, it must be remembered, is an art which demands collaboration between the artist and his public.

E.M. Butler, The Myth of the Magus (1948)

A fire-breathing dragon lives in my garage.’ Suppose (I’m following a group therapy approach by the psychologist Richard Franklin) I seriously make such an assertion to you. Surely you’d want to check it out, see for yourself. There have been innumerable stories of dragons over the centuries, but no real evidence. What an opportunity!

‘Show me,’ you say. I lead you to my garage. You look inside and see a ladder, empty paint cans, an old tricycle - but no dragon.

‘Where’s the dragon?’ you ask.

‘Oh, she’s right here,’ I reply, waving vaguely. ‘I neglected to mention that she’s an invisible dragon.’

You propose spreading flour on the floor of the garage to capture the dragon’s footprints.

‘Good idea,’ I say, ‘but this dragon floats in the air.’

Then you’ll use an infrared sensor to detect the invisible fire.

‘Good idea, but the invisible fire is also heatless.’

You’ll spray-paint the dragon and make her visible.

‘Good idea, except she’s an incorporeal dragon and the paint won’t stick.’

An so on. I counter every physical test you propose with a special explanation of why it won’t work.

Now, what’s the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there’s no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists? Your inability to invalidate my hypothesis is not at all the same thing as proving it true. Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder. What I’m asking you to do comes down to believing, in the absence of evidence, on my say-so.

The only thing you’ve really learned from my insistence that there’s a dragon in my garage is that something funny is going on inside my head. You’d wonder, if no physical tests apply, what convinced me.The possibility that it was a dream or a hallucination would certainly enter your mind. But then why am I taking it so seriously? Maybe I need help. At the least, maybe I’ve seriously underestimated human fallibility.

Imagine that, despite none of the tests being successful, you wish to be scrupulously open-minded. So you don’t outright reject the notion that there’s a fire-breathing dragon in my garage. You merely put it on hold. Present evidence is strongly against it, but if a new body of data emerges you’re prepared to examine it and see if it convinces you. Surely it’s unfair of me to be offended at not being believed; or to criticize you for being stodgy and unimaginative, merely because you rendered the Scottish verdict of ‘not proved’.

Imagine that things had gone otherwise. The dragon is invisible, all right, but footprints are being made in the flour as you watch. Your infrared detector reads off-scale. The spray paint reveals a jagged crest bobbing in the air before you. No matter how sceptical you might have been about the existence of dragons - to say nothing about invisible ones - you must now acknowledge that there’s something here, and that in a preliminary way it’s consistent with an invisible, fire-breathing dragon.

Now another scenario: suppose it’s not just me. Suppose that several people of your acquaintance, including people who you’re pretty sure don’t know each other, all tell you they have dragons in their garages, but in every case the evidence is maddeningly elusive: All of us admit we’re disturbed at being gripped by so odd a conviction so ill-supported by the physical evidence. None of us is a lunatic. We speculate about what it would mean if invisible dragons were really hiding out in garages all over the world, with us humans just catching on. I’d rather it not be true, I tell you. But maybe all those ancient European and Chinese myths about dragons weren’t myths at all ...

Gratifyingly, some dragon-size footprints in the flour are now reported. But they’re never made when a sceptic is looking. An alternative explanation presents itself: on close examination it seems clear that the footprints could have been faked. Another dragon enthusiast shows up with a burned finger and attributes it to a rare physical manifestation of the dragon’s fiery breath. But again, other possibilities exist. We understand that there are other ways to burn fingers besides the breath of invisible dragons. Such ‘evidence’ - no matter how important the dragon advocates consider it - is far from compelling. Once again, the only sensible approach is tentatively to reject the dragon hypothesis, to be open to future physical data, and to wonder what the cause might be that so many apparently sane and sober people share the same strange delusion.

Magic requires tacit cooperation of the audience with the magician - an abandonment of scepticism, or what is sometimes described as the willing suspension of disbelief. It immediately follows that to penetrate the magic, to expose the trick, we must cease collaborating.

How can further progress be made in this emotionally laden, controversial and vexing subject? Patients might exercise caution about therapists quick to deduce or confirm alien abductions. Those treating abductees might explain to their patients that hallucinations are normal, and that childhood sexual abuse is disconcertingly common. They might bear in mind that no client can be wholly uncontaminated by the aliens in popular culture. They might take scrupulous care not subtly to lead the witness. They might teach their clients scepticism. They might recharge their own dwindling reserves of the same commodity.

Purported alien abductions trouble many people and in more ways than one. The subject is a window into the internal lives of our fellows. If many falsely report being abducted, this is cause for worry. But much more worrisome is that so many therapists accept these reports at face value, with inadequate attention given to the suggestibility of clients and to unconscious cuing by their interlocutors.

I’m surprised that there are psychiatrists and others with at least some scientific training, who know the imperfections of the human mind, but who dismiss the idea that these accounts might be some species of hallucination, or some kind of screen memory. I’m even more surprised by claims that the alien abduction story represents true magic, that it is a challenge to our grip on reality, or that it constitutes support for a mystical view of the world. Or, as the matter is put by John Mack, There are phenomena important enough to warrant serious research, and the metaphysics of the dominant Western scientific paradigm may be inadequate fully to support this research.’ In an interview with Time magazine, he goes on to say:

I don’t know why there’s such a zeal to find a conventional physical explanation. I don’t know why people have such trouble simply accepting the fact that something unusual is going on here... We’ve lost all that ability to know a world beyond the physical.*

[* ‘ And then, in a sentence that reminds us how close the alien abduction paradigm is to messianic and chiliastic religion, Mack concludes, ‘I am a bridge between those two worlds.’]

But we know that hallucinations arise from sensory deprivation, drugs, illness and high fever, a lack of REM sleep, changes in brain chemistry and so on, And even if, with Mack, we took the cases at face value, their remarkable aspects (slithering through walls and so on) are more readily attributable to something well within the realm of ‘the physical’ - advanced alien technology -than to witchcraft.

A friend of mine claims that the only interesting question in the alien abduction paradigm is ‘Who’s conning who?’ Is the client deceiving the therapist, or vice versa? I disagree. For one thing, there are many other interesting questions about claims of alien abduction. For another, those two alternatives aren’t mutually exclusive.

Something about the alien abduction cases tugged at my memory for years. Finally, I remembered. It was a 1954 book I had read in college, The Fifty-Minute Hour. The author, a psychoanalyst named Robert Lindner, had been called by the Los Alamos National Laboratory to treat a brilliant young nuclear physicist whose delusional system was beginning to interfere with his secret government research. The physicist (given the pseudonym Kirk Alien) had, it turned out, another life besides making nuclear weapons: in the far future, he confided, he piloted (or will pilot - the tenses get a little addled) interstellar spacecraft. He enjoyed rousing, swashbuckling adventures on planets of other stars. He was ‘lord’ of many worlds. Perhaps they called him Captain Kirk. Not only could he ‘remember’ this other life; he could also enter into it whenever he chose. By thinking in the right way, by wishing, he could transport himself across the light years and the centuries.

In some way I could not comprehend, by merely desiring it to be so, I had crossed the immensities of space, broken out of time, and merged with - literally became - that distant and future self... Don’t ask me to explain. I can’t, although God knows I’ve tried.

Lindner found him intelligent, sensitive, pleasant, polite and perfectly able to deal with everyday human affairs. But, in reflecting on the excitement of his life among the stars, Alien had found himself a little bored with his life on Earth, even if it did involve building weapons of mass destruction. When admonished by his laboratory supervisors for distraction and dreaminess, he apologized; he would try, he assured them, to spend more time on this planet. That’s when they contacted Lindner.

Alien had written 12,000 pages on his experiences in the future, and dozens of technical treatises on the geography, politics, architecture, astronomy, geology, life forms, genealogy and ecology of the planets of other stars. A flavour of the material is given by these monograph titles: “The Unique Brain Development of the Chrysto-peds of Srom Norba X’, ‘Fire Worship and Sacrifice on Srom Sodrat IF, ‘The History of the Intergalactic Scientific Institute’, and ‘The Application of Unified Field Theory and the Mechanics of the Stardrive to Space Travel’. (That last is the one I’d like to see; after all, Alien was said to have been a first-rate physicist.) Fascinated, Lindner pored over the material.

Alien was not in the least shy about presenting his writings to Lindner or discussing them in detail. Unflappable and intellectually formidable, he seemed not to be yielding an inch to Lindner’s psychiatric ministrations. When everything else failed, the psychiatrist attempted something different:

I tried ... to avoid giving in any way the impression that I was entering the lists with him to prove that he was psychotic, that this was to be a tug of war over the question of his sanity. Instead, because it was obvious that both his temperament and training were scientific, I set myself to capitalize on the one quality he had demonstrated throughout his life... the quality that urged him toward a scientific career: his curiosity ... This meant... that at least for the time being I ‘accepted’ the validity of his experiences ... In a sudden flash of inspiration it came to me that in order to separate Kirk from his madness it was necessary for me to enter his fantasy and, from that position, to pry him loose from the psychosis.

Lindner highlighted certain apparent contradictions in the documents and asked Alien to resolve them. This required the physicist to re-enter the future to find the answers. Dutifully, Alien would arrive at the next session with a clarifying document written in his neat hand. Lindner found himself eagerly awaiting each interview, so he could be once more captivated by the vision of abundant life and intelligence in the galaxy. Between them, they were able to resolve many problems of consistency.

Then a strange thing happened: ‘The materials of Kirk’s psychosis and the Achilles heel of my personality met and meshed like the gears of a clock.’ The psychoanalyst became a co-conspirator in his patient’s delusion. He began to reject psychological explanations of Alien’s story. How sure are we that it couldn’t really be true? He found himself defending the notion that another life, that of a spacefarer in the far future, could be entered into by a simple effort of the will.

At a startlingly rapid rate... larger and larger areas of my mind were being taken over by the fantasy... With Kirk’s puzzled assistance I was taking part in cosmic adventures, sharing the exhilaration of the sweeping extravaganza he had plotted.

But eventually, an even stranger thing happened: concerned for the well-being of his therapist, and mustering admirable reserves of integrity and courage, Kirk Alien confessed: he had made the whole thing up. It had roots in his lonely childhood and his unsuccessful relationships with women. He had shaded, and then forgotten, the boundary between reality and imagination. Filling in plausible details and weaving a rich tapestry about other worlds was challenging and exhilarating. He was sorry he had led Lindner down this primrose path.

‘Why,’ the psychiatrist asked, ‘why did you pretend? Why did you keep on telling me…?’

‘Because I felt I had to,’ the physicist replied. ‘Because I felt you wanted me to.’

‘Kirk and I reversed roles,’ Lindner explained,

and, in one of those startling denouements that make my work the unpredictable, wonderful and rewarding pursuit it is, the folly we shared collapsed ... I employed the rationalization of clinical altruism for personal ends and thus fell into a trap that awaits all unwary therapists of the mind... Until Kirk Alien came into my life, I had never doubted my own stability. The aberrations of mind, so I had always thought, were for others ... I am ashamed by this smugness. But now, as I listen from my chair behind the couch, I know better. I know that my chair and the couch are separated only by a thin line. I know that it is, after all, but a happier combination of accidents that determines, finally, who shall lie on the couch, and who shall sit behind it.

I’m not sure from this account that Kirk Alien was truly delusional. Maybe he was just suffering from some character disorder which delighted in inventing charades at the expense of others. I don’t know to what extent Lindner may have embellished or invented part of the story. While he wrote of ‘sharing’ and of ‘entering’ Alien’s fantasy, there is nothing to suggest that the psychiatrist imagined he himself voyaged to the far future and partook of interstellar high adventure. Likewise, John Mack and the other alien abduction therapists do not suggest that they have been abducted; only their patients.

What if the physicist hadn’t confessed? Might Lindner have convinced himself, beyond a reasonable doubt, that it really was possible to slip into a more romantic era? Would he have said he started out as a sceptic, but was convinced by the sheer weight of the evidence? Might he have advertised himself as an expert who assists space travellers from the future who are stranded in the twentieth century? Would the existence of such a psychiatric speciality encourage others to take fantasies or delusions of this sort seriously? After a few similar cases, would Lindner have impatiently resisted all arguments of the ‘Be reasonable, Bob’ variety, and deduced he was penetrating some new level of reality?

His scientific training helped to save Kirk Alien from his madness. There was a moment when therapist and patient had exchanged roles. I like to think of it as the patient saving the therapist. Perhaps John Mack was not so lucky.

Consider a very different approach to finding aliens the radio search for extraterrestrial intelligence. How is this different from fantasy and pseudoscience? In Moscow in the early 1960s, Soviet astronomers held a press conference in which they announced that the intense radio emission from a mysterious distant object called CTA-102 was varying regularly, like a sine wave, with a period of about 100 days. No periodic distant source had ever before been found. Why did they convene a press conference to announce so arcane a discovery? Because they thought they had detected an extraterrestrial civilization of immense powers. Surely, that’s worth calling a press conference for. The report was briefly a media sensation, and the rock group, The Byrds, even composed and recorded a song about it. (‘CTA-102, we’re over here receiving you./ Signals tell us that you’re there./ We can hear them loud and clear...’)

Radio emission from CTA-102? Certainly. But what is CTA-102? Today we know that CTA-102 is a distant quasar. At the time, the word ‘quasar’ had not even been coined. We still don’t know very well what quasars are; and there is more than one mutually exclusive explanation for them in scientific literature. Nevertheless, no astronomers today, including those involved in that Moscow press conference, seriously contend that a quasar like CTA-102 is some extraterrestrial civilization billions of light years away with access to immense power levels. Why not? Because we have alternative explanations of the properties of quasars that are consistent with known physical laws and that do not invoke alien life. Extraterrestrials represent a hypothesis of last resort. You reach for it only if everything else fails.

In 1967, British scientists found a much nearer intense radio source turning on and off with astonishing precision, its period constant to ten or more significant figures. What was it? Their first thought was that it was a message intended for us, or maybe an interstellar navigation and timing beacon for spacecraft that ply the space between the stars. They even gave it, among themselves at Cambridge University, the wry designation LGM-1 - LGM standing for Little Green Men.

However, they were wiser than their Soviet counterparts. They did not call a press conference. It soon became clear that what they were observing was what is now called a ‘pulsar’, the first pulsar to be discovered. So, what’s a pulsar? A pulsar is the end state of a massive star, a sun shrunk to the size of a city, held up as no other stars are, not by gas pressure, not by electron degeneracy, but by nuclear forces. It is in a certain sense an atomic nucleus a mile or so across. Now that, I maintain, is a notion at least as bizarre as an interstellar navigation beacon. The answer to what a pulsar is has to be something mighty strange. It isn’t an extraterrestrial civilization. It’s something else: but a something else that opens our eyes and our minds and indicates unguessed possibilities in Nature. Anthony Hewish won the Nobel Prize in physics for the discovery of pulsars.

The original Ozma experiment (the first intentional radio search for extraterrestrial intelligence), the Harvard University/ Planetary Society META (Megachannel Extraterrestrial Assay) programme, the Ohio State University search, the SERENDIP Project of the University of California, Berkeley, and many other groups have all detected anomalous signals from space that make the observer’s heart palpitate a little. We think for a moment that we’ve picked up a genuine signal of intelligent origin from far beyond our solar system. In reality, we have not the foggiest idea what it is, because the signal does not repeat. A few minutes later, or the next day, or years later you turn the same telescope to the same spot in the sky with the same frequency, bandpass, polarization, and everything else, and you don’t hear a thing. You don’t deduce, much less announce, aliens. It may have been a statistically inevitable electronic surge, or a malfunction in the detection system, or a spacecraft (from Earth), or a military aircraft flying by and broadcasting on channels that are supposed to be reserved for radio astronomy. Maybe it’s even a garage door opener down the street or a radio station a hundred kilometres away. There are many possibilities. You must systematically check out all the alternatives, and see which ones can be eliminated. You don’t declare that aliens have been found when your only evidence is an enigmatic non-repeating signal.

And if the signal did repeat, would you then announce it to the press and the public? You would not. Maybe someone’s hoaxing you. Maybe it’s something you haven’t been smart enough to figure out that’s happening to your detection system. Maybe it’s some previously unrecognized astrophysical source. Instead, you would call scientists at other radio observatories and inform them that at this particular spot in the sky, at this frequency and bandpass and all the rest, you seem to be getting something funny. Could they please see if they can confirm? Only if several independent observers - all of them fully aware of the complexity of Nature and the fallibility of observers - get the same kind of information from the same spot in the sky do you seriously consider that you have detected a genuine signal from alien beings.

There’s a certain discipline involved. We can’t just go off shouting ‘little green men’ every time we detect something we don’t at first understand, because we’re going to look mighty silly - as the Soviet radio astronomers did with CTA-102 - when it turns out to be something else. Special cautions are necessary when the stakes are high. We are not obliged to make up our minds before the evidence is in. It’s permitted not to be sure.

I’m frequently asked, ‘Do you believe there’s extraterrestrial intelligence?’ I give the standard arguments - there are a lot of places out there, the molecules of life are everywhere, I use the word billions, and so on. Then I say it would be astonishing to me if there weren’t extraterrestrial intelligence, but of course there is as yet no compelling evidence for it.

Often, I’m asked next, ‘What do you really think?’

I say, ‘I just told you what I really think.’

‘Yes, but what’s your gut feeling?’

But I try not to think with my gut. If I’m serious about understanding the world, thinking with anything besides my brain, as tempting as that might be, is likely to get me into trouble. Really, it’s okay to reserve judgement until the evidence is in.

I would be very happy if flying saucer advocates and alien abduction proponents were right and real evidence of extraterrestrial life were here for us to examine. They do not ask us, though, to believe on faith. They ask us to believe on the strength of their evidence. Surely it is our duty to scrutinize the purported evidence at least as closely and sceptically as radio astronomers do who are searching for alien radio signals.

No anecdotal claim - no matter how sincere, no matter how deeply felt, no matter how exemplary the lives of the attesting citizens - carries much weight on so important a question. As in the older UFO cases, anecdotal accounts are subject to irreducible error. This is not a personal criticism of those who say they’ve been abducted or of those who interrogate them. It is not tantamount to contempt for purported witnesses.* It is not, or should not be, arrogant dismissal of sincere and affecting testimony. It is merely a reluctant response to human fallibility.

[* They cannot be called, simply, witnesses - because whether they witnessed anything (or, at least, anything in the outside world) is often the very point at issue.]

If any powers whatever may be ascribed to the aliens - because their technology is so advanced - then we can account for any discrepancy, inconsistency or implausibility. For instance, one academic UFOlogist suggests that both the aliens and the abduct-ees are rendered invisible during the abduction (although not to each other); that’s why more of the neighbours haven’t noticed. Such ‘explanations’ can explain anything, and therefore in fact nothing.

American police procedure concentrates on evidence and not anecdotes. As the European witch trials remind us, suspects can be intimidated during interrogation; people confess to crimes they never committed; eyewitnesses can be mistaken. This is also the linchpin of much detective fiction. But real, unfabricated evidence - powder burns, fingerprints, DNA samples, footprints, hair under the fingernails of the struggling victim - carry great weight. Criminalists employ something very close to the scientific method, and for the same reasons. So in the world of UFOs and alien abductions, it is fair to ask: where is the evidence - the real, unambiguous physical evidence, the data that would convince a jury that hasn’t already made up its mind?

Some enthusiasts argue that there are ‘thousands’ of cases of ‘disturbed’ soil where UFOs supposedly landed, and why isn’t that good enough? It isn’t good enough because there are ways of disturbing the soil other than by aliens in UFOs - humans with shovels is a possibility that springs readily to mind. One UFOlogist rebukes me for ignoring ‘4,400 physical trace cases from 65 countries’. But not one of these cases, so far as I know, has been analysed with results published in a peer-reviewed journal in physics or chemistry, metallurgy or soil science, showing that the ‘traces’ could not have been generated by people. It’s a modest enough scam compared, say, with the crop circles of Wiltshire.

Likewise, not only can photographs easily be faked, but huge numbers of alleged photographs of UFOs have without a doubt been faked. Some enthusiasts go out night after night into a field looking for bright lights in the sky. When they see one, they flash their flashlights. Sometimes, they say, there’s an answering flash. Well, maybe. But low-altitude aircraft make lights in the sky, and pilots are able, if so inclined, to blink their lights back. None of this constitutes anything approaching serious evidence.

Where is the physical evidence? As in satanic ritual abuse claims (and echoing ‘Devil’s marks’ in the witch trials), the most common physical evidence pointed to are scars and ‘scoop marks’ on the bodies of abductees - who say they have no knowledge of where their scars came from. But this point is key: if the scars are within human capacity to generate, then they cannot be compelling physical evidence of abuse by aliens. Indeed, there are well-known psychiatric disorders in which people scoop, scar, tear, cut and mutilate themselves (or others). And some of us with high pain thresholds and bad memories can injure ourselves accidentally with no recollection of the event.

One of John Mack’s patients claims to have scars all over her body that are wholly baffling to her physicians. What do they look like? Oh, she can’t show them; as in the witch mania, they’re in private places. Mack considers this compelling evidence. Has he seen the scars? Can we have photographs of the scars taken by a sceptical physician? Mack knows, he says, a quadriplegic with scoop marks and considers this a reductio ad absurdum of the sceptical position; how can a quadriplegic scar himself? The argument is a good one only if the quadriplegic is hermetically sealed in a room to which no other human has access. Can we see his scars? Can an independent physician examine him? Another of Mack’s patients says that the aliens have been taking eggs from her since she was sexually mature, and that her reproductive system baffles her gynaecologist. Is it baffling enough to write the case up and submit a research paper to The New England Journal of Medicine”? Apparently it’s not that baffling.

Then we have the fact that one of his subjects made the whole thing up, as reported by Time magazine, and Mack didn’t have a clue. He bought it hook, line and sinker. What are his standards of critical scrutiny? If he allowed himself to be deceived by one subject, how do we know the same wasn’t true of all?

Mack talks about these cases, the ‘phenomena’, as posing a fundamental challenge to western thinking, to science, to logic itself. Probably, he says, the abducting entities are not alien beings from our own universe, but visitors from ‘another dimension’. Here’s a typical, and revealing, passage from his book:

When abductees call their experience ‘dreams’, which they often do, close questioning can elicit that this may be a euphemism to cover what they are sure cannot be that, namely an event from which there was no awakening that occurred in another dimension.

Now the idea of higher dimensions did not arise from the brow of UFOlogy or the New Age. Instead, it is part and parcel of the physics of the twentieth century. Since Einstein’s general relativity, a truism of cosmology is that space-time is bent or curved through a higher physical dimension. Kaluza-Klein theory posits an eleven-dimensional universe. Mack presents a thoroughly scientific idea as the key to ‘phenomena’ beyond the reach of science.

We know something about how a higher-dimensional object would look in encountering our three-dimensional universe. For clarity, let’s go down one dimension: an apple passing through a plane must change its shape as perceived by two-dimensional beings confined to the plane. First it seems to be a point, then larger apple cross-sections, then smaller ones, a point again, and finally - poof! - gone. Similarly, a fourth- or higher-dimensional object - provided it’s not a very simple figure such as a hypercyl-inder passing through three dimensions along its axis - will wildly alter its geometry as we witness it passing through our universe. If aliens were systematically reported as shape-changers, I could at least see how Mack might pursue the notion of a higher-dimensional origin. (Another problem is trying to understand what a genetic cross between a three-dimensional and a four-dimensional being means. Are the offspring from the 3ldimension?)

What Mack really means when he talks about beings from other dimensions is that, despite his patients’ occasional descriptions of their experiences as dreams and hallucinations, he hasn’t the foggiest notion of what they are. But, tellingly, when he tries to describe them, he reaches for physics and mathematics. He wants it both ways - the language and credibility of science, but without being bound by its method and rules. He seems not to realize that the credibility is a consequence of the method.

The main challenge posed by Mack’s cases is the old one of how to teach critical thinking more broadly and more deeply in a society - conceivably even including Harvard professors of psychiatry - awash in gullibility. The idea that critical thinking is the latest western fad is silly. If you’re buying a used car in Singapore or Bangkok, or a used chariot in ancient Susa or Rome, the same precautions will be useful as in Cambridge, Massachusetts.

When you buy a used car, you might very much want to believe what the salesman is saying: ‘So much car for so little money!’ And anyway, it takes work to be sceptical; you have to know something about cars, and it’s unpleasant to make the salesman angry at you. Despite all that, though, you recognize that the salesman might have a motive to shade the truth, and you’ve heard of other people in similar situations being taken. So you kick the tyres, look under the hood, go for a test drive, ask searching questions. You might even bring along a mechanically inclined friend. You know that some scepticism is required and you understand why. There is usually at least a small degree of hostile confrontation involved in the purchase of a used car and nobody claims it’s an especially cheering experience. But if you don’t exercise some minimal scepticism, if you have an absolutely untrammelled gullibility, there’s a price you’ll have to pay later. Then you’ll wish you had made a small investment of scepticism early on.

Many homes in America now have moderately sophisticated burglar alarm systems, including infrared sensors and cameras triggered by motion. An authentic videotape, with time and date denoted, showing an alien incursion - especially as they slip through the walls - might be very good evidence. If millions of Americans have been abducted, isn’t it strange that not one lives in such a home?

Some women, so the story goes, are impregnated by aliens or alien sperm; the foetuses are then removed by the aliens. Vast numbers of such cases are alleged. Isn’t it odd that nothing anomalous has ever been seen in routine sonograms of such foetuses, or in amniocentesis, and that there has never been a miscarriage producing an alien hybrid? Or are medical personnel so doltish that they idly glance at the half-human, half-alien foetus and move on to the next patient? An epidemic of missing foetuses is something that would surely cause a stir among gynaecologists, midwives, obstetrical nurses, especially in an age of heightened feminist awareness. But not a single medical record has been produced substantiating such claims.

Some UFOlogists consider it a telling point that women who claim to have been sexually inactive wind up pregnant, and attribute their state to alien impregnation. A goodly number appear to be teenagers. Taking their stories at face value is not the only option available to the serious investigator. Surely we can understand why, in the anguish of an unwanted pregnancy, a teenager living in a society flooded with accounts of alien visitation might invent such a story. Here, too, there are possible religious antecedents.

Some abductees say that tiny implants, perhaps metallic, were inserted into their bodies, high up their nostrils, for example. These implants, alien abduction therapists tell us, sometimes accidentally fall out, but ‘in all but a few of the cases the artefact has been lost or discarded’. These abductees seem stupefyingly incurious. A strange object, possibly a transmitter sending telemetered data about the state of your body to an alien spaceship somewhere above the Earth, drops out of your nose; you idly examine it and then throw it in the garbage. Something like this is true, we are told, of the majority of abduction cases.

A few such ‘implants’ have been produced and examined by experts. None has been confirmed as of unearthly manufacture. No components are made of unusual isotopes, despite the fact that other stars and other worlds are known to be constituted of different isotopic proportions from the Earth. There are no metals from the transuranic ‘island of stability’, where physicists think there should be a new family of non-radioactive chemical elements unknown on Earth.

What abduction enthusiasts considered the best case was that of Richard Price, who claims that aliens abducted him when he was eight years old and implanted a small artefact in his penis. A quarter century later a physician confirmed a ‘foreign body’ embedded there. After eight more years, it fell out. Roughly a millimetre in diameter and four millimetres long, it was carefully examined by scientists from MIT and Massachusetts General Hospital. Their conclusion? Collagen formed by the body at sites of inflammation plus cotton fibres from Price’s underpants.

On 28 August 1995, television stations owned by Rupert Murdoch ran what was purported to be an autopsy of a dead alien, shot on 16-millimetre film. Masked pathologists in vintage radiation-protection suits (with rectangular glass windows to see out of) cut up a large-eyed 12-fingered figure and examined the internal organs. While the film was sometimes out of focus, and the view of the cadaver often blocked by the humans crowding around it, some viewers found the effect chilling. The Times of London, also owned by Murdoch, didn’t know what to make of it, although it did quote one pathologist who thought the autopsy performed with unseemly and unrealistic haste (ideal, though, for television viewing). It was said to have been shot in New Mexico in 1947 by a participant, now in his eighties, who wished to remain anonymous. What appeared to be the clincher was the announcement that the leader of the film (its first few feet) contained coded information that Kodak, the manufacturer, dated to 1947. However, it turns out that the full film magazine was not presented to Kodak, just the cut leader. For all we know, the leader could have been cut from a 1947 newsreel, abundantly archived in America, and the ‘autopsy’ staged and filmed separately and recently. There’s a dragon footprint all right - but a fakable one. If this is a hoax, as I think likely, it requires not much more cleverness than crop circles and the MJ-12 document.

In none of these stories is there anything strongly suggestive of extraterrestrial origin. There is certainly no retrieval of cunning machinery far beyond current technology. No abductee has filched a page from the captain’s logbook, or an examining instrument, or taken an authentic photograph of the interior of the ship, or come back with detailed and verifiable scientific information not hitherto available on Earth. Why not? These failures must tell us something.

Since the middle of the twentieth century, we’ve been assured by proponents of the extraterrestrial hypothesis that physical evidence - not star maps remembered from years ago, not scars, not disturbed soil, but real alien technology - was in hand. The analysis would be released momentarily. These claims go back to the earliest crashed saucer scam of Newton and GeBauer. Now it’s decades later and we’re still waiting. Where are the articles published in the refereed scientific literature, in the metallurgical and ceramics journals, in publications of the Institute of Electrical and Electronic Engineers, in Science or Nature?

Such a discovery would be momentous. If there were real artefacts, physicists and chemists would be fighting for the privilege of discovering that there are aliens among us who use, say, unknown alloys, or materials of extraordinary tensile strength or ductility or conductivity. The practical implications of such a finding, never mind the confirmation of an alien invasion, would be immense. Discoveries like this are what scientists live for. Their absence must tell us something.

Keeping an open mind is a virtue - but, as the space engineer James Oberg once said, not so open that your brains fall out. Of course we must be willing to change our minds when warranted by new evidence. But the evidence must be strong. Not all claims to knowledge have equal merit. The standard of evidence in most of the alien abduction cases is roughly what is found in cases of the apparition of the Virgin Mary in medieval Spain.

The pioneering psychoanalyst, Carl Gustav Jung, had much that was sensible to say on issues of this sort. He explicitly argued that UFOs were a kind of projection of the unconscious mind. In a related discussion of regression and what today is called ‘channelling’, he wrote

One can very well... take it simply as a report of psychological facts or a continuous series of communications from the unconscious... They have this in common with dreams; for dreams, too, are statements about the unconscious... The present state of affairs gives us reason enough to wait quietly until more impressive physical phenomena put in an appearance. If, after making allowance for conscious and unconscious falsification, self-deception, prejudice, etc., we should still find something positive behind them, then the exact sciences will surely conquer this field by experiment and verification, as has happened in every other realm of human experience.

Of those who accept such testimony at face value, he remarked

These people are lacking not only in criticism but in the most elementary knowledge of psychology. At bottom they do not want to be taught any better, but merely to go on believing -surely the naivest of presumptions in view of our human failings.

Perhaps some day there will be a UFO or alien abduction case that is well attested, accompanied by compelling physical evidence, and explicable only in terms of extraterrestrial visitation. It’s hard to think of a more important discovery. So far, though, there have been no such cases, nothing that comes close. So far, the invisible dragon has left no unfakable footprints.

Which, then, is more likely: that we’re undergoing a massive but generally overlooked invasion by alien sexual abusers, or that people are experiencing some unfamiliar internal mental state they do not understand? Admittedly, we’re very ignorant both about extraterrestrial beings, if any, and about human psychology. But if these really were the only two alternatives, which one would you pick?

And if the alien abduction accounts are mainly about brain physiology, hallucinations, distorted memories of childhood, and hoaxing, don’t we have before us a matter of supreme importance, touching on our limitations, the ease with which we can be misled and manipulated, the fashioning of our beliefs, and perhaps even the origins of our religions? There is genuine scientific paydirt in UFOs and alien abductions - but it is, I think, of a distinctly home-grown and terrestrial character.