What an enticing prospect: A-Z elucidation, or at least the admission in print that most of life’s pressing questions are never answered. But won’t all the entries begin with ‘W’? Where has youth gone? Why dost thou lash that whore? Why are you looking at me like that? And of course the question that trails us from playgroup to dementia ward: well, if you will go on like that, what else did you expect?

But of course we’re not dealing with that kind of unexplained. The clue is on the cover: a person with popping eyes, flying through the air. This dictionary’s greatest fans will be people more interested in the exception than the rule, and often, it must be said, ignorant of what the rule is. To many of us, a great deal of what we encounter daily is unexplained. If you are in mid-life now, it is possible to have received what was described at the time as a good education and still know nothing of science or technology. Those on the other side of the cultural divide complain that the artists are proud of their deficiency, but this is seldom so. It’s easy, if you can read, to brush up your Shakespeare, but not so easy to use your spare half-hours to catch up on the inorganic chemistry you missed. It’s the people cringing from their scientific illiteracy who buy Stephen Hawking books they can’t read, as if having them on the shelf will make the knowledge rub off; they snap up tracts on atheism, too, to show that if they’re ignorant they’re at least rational. But still, our understanding of the mechanisms of the world remains fuzzy around the edges. If we were told that our computer worked because there was an angel inside, some of us couldn’t disprove it. The cultures were undivided in Leonardo’s day, but now those of us who deal in metaphors don’t know how to make machines. If we wanted to move a mountain, we would have to rely on faith.

The compilers of the dictionary have adopted a gentle, judicious, sometimes jaunty tone. There is at least one gratifying juxtaposition: the entry for Padre Pio, recently canonised under the papal fast-track procedure, appears on the same page as ‘pious fraud’. The entries, the editors say, represent the full range of positions ‘from the hostile sceptic to the credulous believer’. They have tried to operate without bias, avoid empty speculation and run to earth misconceptions, and they have cross-referenced liberally and cleverly. On the whole, a sobriety of tone prevails. Only a few entries feature sentences like: ‘The aliens returned, exchanging barking sounds with one another as they stripped him naked and sponged him down.’ The compilers are good at pinning down the origin of urban legends, and rural ones too. Alligators in the sewers of New York? Probably not, though alien big cats are real enough. Spectral pedestrians are never children, though many children are killed on the roads. They are better attested than phantom hitch-hikers, though the latter predate the motor car: there is a 17th-century case in Sweden in which a sleigh is involved. In keeping with the casualness of modern corpse disposal, phantom funeral processions are less popular than they were. On the whole, though, the older the world gets, the less we can explain and the more mysteries proliferate. Most anomalous phenomena are marginal, and are dull if only the strict truth is told, so even people anxious to be factual will embroider them in an effort to secure attention for the strange thing they witnessed, or half-witnessed. Maybe people once felt some reticence if they saw a spectre, a UFO, or the great god Pan in a grove, but we are a society beyond embarrassment now. Accordingly, the dictionary is in large part a record of mass hysteria, as well as factoids and fakes. Meet the Mad Gasser of Mattoon, Gef the Talking Mongoose and, more prosaically, Doug and Dave, self-confessed manufacturers of crop circles. Thrill to ‘penis panic’ – five dead in Benin. If that’s too culture-specific, consider joining an epidemic of mass-psychogenic illness: dizzy spells and vomiting seem to be international in their appeal and destined to be more popular than ever as odourless poison gas released by terrorists seeps into the places of the psyche no suicide bomber can reach.

Some people will be offended by the existence of the dictionary and its efforts at even-handedness, and will want to turn first to ‘scepticism’ and ‘hoaxes’. The American sociologist Marcello Truzzi discerned various categories of sceptic. First there are ‘proponents’, who have encountered one specific oddity, or hatched one peculiar idea, and want to bring it within the ambit of scientific knowledge, make it respectable; single-track obsessives, they are not interested in being dragged into the swamp of the paranormal. ‘Anomalists’, more broadly, seek to enhance scientific knowledge. Confronted with puzzling phenomena, they are willing to take an interdisciplinary approach, and realise that what is under investigation may not fit existing paradigms. They apply Occam’s razor, and try to test claims using existing methodology. They put the burden of proof on the claimant. A third category, ‘mystery-mongers’, are ‘fundamentally unscientific’. They don’t really want explanations. What they are sceptical about is the scientific consensus. Broadly, they are out for fun, at the expense of the establishment; but perhaps we should put in this category those who get little pleasure and much pain from paranoid ideas about how the world works: simmering psychosis finds a ready vocabulary in pseudoscience. Among the most angry, hostile and sceptical people of all are those who are about to divorce from the general consensus of how the world works, because they are convinced that a big secret about the cosmos is being kept from them by a conspiracy among their friends.

Then there is another category, the large and familiar category of ‘scoffers’. Scoffers begin by assuming that anomalous phenomena are invalid. They are mentally rigid and doctrinaire, and insist that science – that wilting flower – is under threat from those who are not as good as they are at critical thinking. Though commonly elitist in their assumptions, they present themselves as stout defenders of the public interest, standing between the great unwashed and the army of charlatans out to make fools of them. They idealise scientific procedures and what they take to be the scientific mindset, claiming that scientists are pure because they work from a position of ignorance to a position of knowledge; really, of course, they work from a position of expectation. The crudity of public discourse means that the mystery-mongers and the scoffers get all the attention. The anomalists have history on their side. The writer of the dictionary’s preface takes their part when he says, ‘Most of our subjects are not science – yet.’

There is a long list of natural phenomena and human inventions that lurked on the fringes of science before they became officially credible. At the end of the 18th century, the French Academy of Sciences said with impeccable Gallic logic that, as there were no rocks in the sky, no rocks could fall from the sky. In 1803, more than two thousand meteorites fell on a village in Normandy – after that, and an investigation by the scientist Jean-Baptiste Biot, the Academy was less sniffy. The eminent scientist Lord Kelvin said that Roentgen’s X-rays were a hoax. Edison’s electric lamp was declared an impossibility, and because it was an impossibility his fellow researchers wouldn’t go to see it even when Edison used it to light up the streets around his laboratory. From 1904, the Wright brothers made flights over fields bordered by a main highway and a railway line in Ohio: but though hundreds of people saw them in the air, the local press failed to publish reports because they didn’t believe the witnesses, and didn’t send their own witnesses because it couldn’t be true. Two years after their first flight, Scientific American dismissed the feats of the flying brothers; if there had been anything in it, the journal said, wouldn’t the local press have picked it up?

But maybe it’s easier now to evade taboos and get a hearing for nonsense. The internet has so vastly increased the potency of urban legends, so quickened the circulation of rumours, that we may soon be the most deluded generation ever born. It seems strange that some scientists are so angry with the sacred books of old-time religions, when so many challenges to rationality are generated by half-understood, miscommunicated information, much of it masquerading as science, available online and in the press. The internet is the great source of light and of darkness; it trashes the status of knowledge, undermines its ownership, and scants the principle of editing and review. The laconic conventions that govern online communication favour the proliferation of irony, of a two-way split of meaning in every line, so that the knowing prevail effortlessly over the naive. Fleeting and flitting, self-generating, double-faced, the internet is the natural home for anomalous phenomena, which have a primitive quality, yet track social paradigms; like science fiction, they dance like sprites around the scientific consensus, sometimes seeming to follow, sometimes to lead, sometimes to head off by themselves into an ancient inner landscape.

Until the idea of space flight became credible, there were no aliens; instead there were green men who hid in the woods. In the same way, psychotic delusions keep up with scientific change: the people once pursued by phantasms of the dead are now pestered by living celebrities who watch them from inside their TV sets, and those who used to confess themselves possessed now say there is a bomb inside them. The dictionary attests to the power and antiquity of the need to believe we are sharing the planet with beings not animal and not human, with ‘little greys’ from spacecraft, with goblins and domestic deities: beings who suspend the laws of nature wherever they pop up, and suspend moral laws too, for household sprites and pucks often have a fierce, childlike sense of justice, and retaliate without fear if they are slighted; aliens who want sex never ask nicely. On the lonely road by moonlight, the parts of ourselves oppressed by our intelligence come out to play. We meet ancestral selves, neither gods nor demons but short semi-humans with hairy ears and senses differently attuned – the eyesight of an eagle, the nose of a hound. The phenomena are internal, generated by the psychological mechanisms that connect us to each other and to our evolutionary past.

Aware of this, and acknowledging that, as the dictionary says, ‘a small percentage of the population appear to have such vivid imaginations that they can find it hard to distinguish between reality and illusion,’ should the rationalist who is confronted by alternative explanations for the world be steaming mad, mildly irritated or sadly amused? It is not hard to see that human activity may be valuable and interesting, without being amenable to scientific analysis. Most work by ‘psychics’ hovers between therapy, art and entertainment. You can’t repeat it under test conditions, and you can’t measure it; you can’t be objective about it, because the subjective is of its essence. When eccentric thinking is cultivated by powerful political interests, scientists do need to throw their weight behind the consensus; one thinks of Aids denialism in South Africa, a heresy with fatal consequences for patients who were denied antiretroviral drugs. But eccentricities of thought, though they collect adherents, usually affect small numbers and are grounded in private lives. Alternative medicine and its practitioners are seldom so dangerous that they merit the scathing attacks mounted on them by the orthodox. Patients who turn to alternative therapies often do so because their illness has a large psychosomatic component which their doctors don’t take into account, or because they want to take charge of themselves in a way that the system doesn’t permit; given that most conditions are self-limiting, they come to no harm, and by thinking about their situation and making their own choices they potentiate the placebo effect. The unverifiable practices of healers are usually neither as profitable nor as outrageous as the conduct of the drugs companies, who have invented whole categories of disease, such as ‘social anxiety disorder’, as a means of off-loading their products. Truzzi’s ‘scoffers’ have a strong belief that people need to be protected from themselves, but sometimes they identify the threat in the wrong quarter.

In fact, if you hang around the anomalous long enough, you see that most people within its range have an unexpressed but quite sophisticated sense of ambiguity. They go to a ‘psychic fayre’ in a spirit of temporary suspension of disbelief; it is just as if they had picked up a novel. For a limited time, events unfold around them as a powerful second reality. They read the story, or listen to the dead talk in a public hall; two hours pass; they close the book or rise from their seat, they shut down that other world, run out into the high street and go looking for a pizza. In Britain, where mainstream religion is dwindling into a mix of apathy and superstition, alternative views are not part of the counter-culture but part of popular culture, with its extensive TV spooks programming and Mind-Body-Spirit events held every weekend in sports halls up and down the country: the ineffable now smells of stale sweat and hot feet. An olla podrida of new age hogwash is served up to anyone who has a spare tenner and seems likely to part with it. We are only in the market for fun-size beliefs, unlike the US, where the aggressive fundamentalist irrationality of evangelical Christianity moves real money around, affects how children are educated, and darkens believers’ perceptions of other cultures. On the whole, we have the better part: superstition is easier to accommodate in the body politic than religion. It is less divisive: no one ever went to war about what you should chant when you see a magpie, or was burned at the stake for denying the reality of the Loch Ness Monster.

Again, it’s debatable which set of people do more damage in society – the credulous, or the dogmatic. The worst case is that they get together: keen believers enthralled by doctrinaire fanatics. The devil appeared in modern society during the ‘satanic ritual abuse’ scandal of the 1980s, a panic that affected gullible social workers in this country and led to the removal of children from their families in Rochdale, Nottingham and the Orkneys. This malign fashion seemed to break out simultaneously in the UK, Australia, New Zealand and the Netherlands, but actually followed, the dictionary says, the visits of ‘experts’ in the field from the US. It was a folk-panic; it made us think of the Salem witches. But then, the 1980s were like that. According to the dictionary, there were social occasions – like Abigail’s Party, but more paranormal – which featured ‘groups of people, sitting in a circle, shouting at cutlery in an attempt to make it bend’. You were safer at home watching TV – at least until 1992, when the BBC broadcast Ghostwatch. Supposedly a live broadcast from a haunted house somewhere in London, with well-known presenters linking to Michael Parkinson in the studio, it was in fact a scripted recording; the reports from the house, interrupted by invented telephone calls from ‘concerned viewers’, degenerated into contrived havoc, and were ended by evil forces invading the studio, and ‘Parkinson grunting incoherently at the camera, supposedly possessed by an entity from the house’.

‘Parky Panned for Halloween Fright’ ran the headline in the News of the World. If it were broadcast now, no mere ‘panning’ would do; there would be executions. If I ever knew about Ghostwatch I have repressed it (see ‘cryptomnesia’), but naturally you can turn up plenty of chat about it on the internet, including the allegation (on a site called Museum of Hoaxes) that the fright it gave the nation caused women to go into labour and teenagers to commit suicide. Hoaxes build on hoaxes. The dictionary makes its readers long for the innocent days of the Jersey Devil, exhibited in Philadelphia in 1909. It was merely a kangaroo painted with bright green stripes and equipped with strap-on wings; even in those innocent days it fooled nobody. In the case of mediums, clairvoyants and other psychic operators, there’s a fine line between cheating and self-delusion, and it is worrying that people who claim to expose hoaxes are often no more scrupulous in their conduct than the people they are pursuing. The history of spiritualism is blighted not only by fraud but by the vindictive pleasure investigators have taken in exposing cheats who are often fragile and vulnerable people, caught up in scams that have run out of their control. Readers of Malcolm Gaskill’s Hellish Nell, about Helen Duncan, the spirit medium who was tried during World War Two under the 1735 Witchcraft Act, will remember the background of grim poverty and social deprivation against which Duncan’s public life began; this background is possibly more interesting than her fraudulent claims. The makers of the dictionary try hard, working within the limitations of space, to describe the context of the phenomena under review, and sometimes make a virtue of brevity. They have managed in one paragraph to describe the memory system of the Catalan mystic Ramón Llull – one of those things that generally, the more you read about it, the less you understand.

Of course, there’s nothing necessarily magical about the ‘art of memory’, which was once – as Frances Yates’s formidable book on the subject explains – as much the province of lawyers as of magi. Its cultivation depends on powers to visualise and to generate and interpret symbols that most modern people never explore. Many of the dictionary’s entries point less to the unexplained than the unexplored: to the strange potentials thrown up by the workings of the mind. The balance of the compilers’ interest, though, is discernible; they are less interested in cultural history and psychology than in the geekier topics of cryptozoology and UFOs. They tackle astrology summarily, oddly not mentioning Michel and Françoise Gauquelin, who seem natural inhabitants of these pages. Researchers who began to publish in the 1950s, the Gauquelins set out to explore the correlation, if any, between planetary positions in an individual’s horoscope and the careers which their subjects took up. There was a huge dispute in the 1970s about their methods and the statistics which resulted from them, but – to the alarm of the establishment – an anomalous ‘Mars effect’ in the charts of athletes was detected. It was rapidly undetected, by further study, but there were allegations that the debunkers themselves cheated. The row had all the hallmarks of paranormal investigations: complex disputes over protocol, allegations of bad faith, misunderstanding of the question asked and distortion of the answer given.

The Gauquelins’ research gave no comfort to practitioners of traditional astrology; perhaps it was because they were unloved on all sides that they seem to have vanished from the dictionary’s radar, or are at least lurking out of the way of any search I could make. But usually, the unexplained doesn’t simply go away. It reproduces and augments itself. A mystery-generating mechanism goes to work, whereby the allegorical becomes concrete and crude. A feeling of pervasive unease becomes a headless woman on the stairs, the wind in the trees becomes a voice with a specific complaint. Peter Weir’s 1975 film, Picnic at Hanging Rock, about a group of Australian schoolgirls who go missing, was based on a novel, not a real event, and it concerns – I think – the blink-and-you-miss-it nature of innocence. The story, the dictionary tells us, is now taken to be based on a real incident. When imaginative writers are on the scene, the mystery always deepens. The story of the Mary Celeste was only averagely mysterious before Conan Doyle got to work on it.

If the multiple oddities of the dictionary are not enough for you, you can make your own ghost. Under the heading ‘Philip Experiment’ is an account of a group of paranormalists from Toronto – presumably with time on their hands, as they were too dull to be invited to cutlery parties – who in 1972 collectively imagined an entity called Philip, and furnished him with a lurid history. They then tried to communicate with him, and in time Philip obliged by rapping on a table, in the time-honoured manner of spooks on the loose. Later, when requested, he caused the table to levitate; but ‘having established a limited range of phenomena, interest in the project waned and the group ceased their sittings in 1978.’ Why ghosts, manufactured or otherwise, are supposed to be interested in moving furniture is a topic the dictionary nowhere tackles.

The last word goes to Eleonore Zugun, born in a Romanian village in 1913, whose troubles began when her grandmother, perhaps making a metaphor, told her she had swallowed the devil. Subsequently, she was regularly mauled. She was photographed with claw-marks on her face, and when he was angry ‘Dracu’ would bite her and raise weals on her arms. She was taken to a convent, and then to ‘some form of institution’. She was shipped off to Vienna and to London, a paranormal freak who caused the mysterious movement of objects in her vicinity. What is really unexplained and perhaps inexplicable is human resilience, in the teeth of both diabolic interference and the keen international investigation to which she was subject. When she reached puberty, the devil decided to leave her be, and Eleonore went home, and became a hairdresser.