This conspiracy goes deeper than you thought. Fox Mulder, high priest of UFO conspiracy theory, was a triple agent all along. The faded poster always in shot during heated debates in Mulder’s basement office proclaimed the fatal fallacy at the heart of the UFO creed: ‘I Want To Believe’. If a belief is based on need, it is unlikely to be based on objective fact. Or, as any science student will confirm, if a scientist sets out to prove a predetermined theory, it is all too tempting for them to embrace facts that support that theory and jettison the rest.

The very term UFO has been abused; an unidentified flying object is just that, rather than an interstellar voyager which must be knowingly referred to as a UFO in case The Man is tapping our calls. UFO theorists tend to be creative and sensitive people, so sensitive that they’re afraid of cutting themselves on Occam’s Razor. To paraphrase that principle, to stand any chance of being truthful, a theory should dispense with as many far flung or bizarre assumptions as possible. It is one thing to see strange lights in the sky; it is an outrageous leap to suppose that because we can’t explain them they must be extra-terrestrial tourists.

Not that extra-terrestrial visits are impossible; they are just wildly improbable compared to the mundane truth of most sightings. The list of suspects is long and distinguished: hallucination, collective or otherwise; weather balloons; satellites, falling or orbiting; aircraft of all shapes and sizes; atmospheric, magnetic and solar phenomena; meteorites; our own spacecraft. From time to time, a sighting will defy explanation, but that doesn’t entitle us to pin a fantasy to it. For example, can we really presume to know everything about how our own atmosphere interacts with our solar system?

As for a military conspiracy, is there really anything strange or sinister about cutting edge military contractors not sharing their latest findings with the world? Secrecy in matters of defence technology is de rigueur and always has been. Some now familiar aeronautical marvels were once jealously guarded secrets whose outlandish appearance might have sparked all kinds of yarn-weaving before their public debut. The SR71 first flew more than forty years ago, the B2 more than twenty: military science doesn’t stand still and doesn’t shout about its achievements. Any public servant or defence contractor who signs the Official Secrets Act is in on the conspiracy, if you feel compelled to call it that.

Besides, don’t conspiracy theories of all kinds give too much credit to governments? Considering the intelligence failures, whistle-blowing, and domestic and foreign policy disasters of the last decade alone, can government as we know it really be capable of stage-managing the kind of labyrinthine and delicate conspiracies that Mulder used to be so fond of? How can it be that the nation which salvaged a bone fide spacecraft at Roswell has only just managed to create a supersonic VTOL fighter and is still soldiering on with the crude and dangerous Space Shuttle?

Perhaps I want to disbelieve in UFO conspiracies. Am I just as guilty of cherry-picking facts to fit a preconceived case? Maybe. Yet I believe wholeheartedly in extra-terrestrial life. Such is the incomprehensible size of our universe, it seems inconceivable that we are entirely alone. However, UFO theorists should think hard about spacetime rather than space in isolation. Not only could we be separated from other sentient life by millions of light years, we could equally well be separated by millions of calendar years, and that’s without considering travelling time. Even if another sentient species had mastered FTL travel and propelled itself in the right direction, the odds against them occupying a sufficiently proximate niche in spacetime to happen upon us are, well, astronomical.

And if such a mighty civilisation managed this feat, would they have done so just to probe the gullible, molest cattle and tease airline pilots? I wouldn’t presume to know how an advanced xenoc thinks or feels about such matters, but the activities usually ascribed to them don’t seem to justify the effort involved in getting here. Having said that, the Apollo programme cost $25 billion in 1969 dollars and the benefits might not be obvious to an outside observer: one unsatisfactory game of golf, an extreme sports holiday for 21 Americans and a quantity of interesting rocks moved 250,000 miles.

The most objectionable aspect of UFO conspiracy theories is the old fashioned geocentric hubris behind it. We can’t resist seeing ourselves as the centre of the universe and therefore the most fascinating thing in it. Even when we colour in the vast blank spaces left by UFO sightings, we create spacecraft crewed by humanoids who reflect the cultural preoccupations of our times. In the white heat of the Cold War, they’re obsessed with our technological advances. In a more climatologically aware age, they’re fleeing a barren homeworld for our blue-green oasis. Choose whatever fairy tale suits you.

As some good and bad sci-fi writers have suggested, for any xenoc race to go to the time and trouble of getting here, they’d have to have a very good reason. We wouldn’t be shaking hands and staging light shows with frail, benevolent humanoids interested only in curing cancer and swapping CD collections. We might find ourselves quite reasonably regarded as vermin by superior and incomprehensible beings who want our real estate. We should be careful what we wish for.

If you want to believe a thing before you’ve even seen it, the chances of your seeing the truth are slim indeed. I must sign off. The Man is buying me lunch.