Hell hath no fury like an expert scorned. Consider the scenario. These are people who dedicate their waking hours to the gathering of knowledge in their chosen subject. They are all, in their little niches, masterminds. And as their expertise grows, so does their arrogance. Why not? Their specialist areas may be tiny, but inside those mini-jungles they are mighty beasts. You cross or contradict them at your peril. They know best. Their word is law!

But then something totally unexpected pops out of the undergrowth and bites them on their pompous backsides. They are thrown off balance. They lose their bearings in the jungle they thought they knew so well. What's worse, everyone has noticed. The press are laughing, or screaming for blood. After all, aren't experts supposed to predict imminent problems in their respective fields, and take steps to avert disasters - or at least to warn the rest of us? If they can't do that, what's the point of them?

I know that this bizarre annus topsi turvius still has six weeks to run. But I'm ready to sum up 2008 now. It's the Year When the Experts Lost the Plot. And with it, status and credibility. I'll go farther. This is the year in which the 21st century really started. But more of that later.

Where have we seen experts fail? Well, where do you want to start? How about in the world of high finance, where thousands of bankers and economists, in the public as well as private sector, spectacularly failed to predict what in retrospect looks like a catastrophe waiting to happen? And a catastrophe, moreover, that owed nothing to bad luck or “an act of God”, but was unwittingly wrought by financiers themselves.

Or how about in the tragedy of Baby P, and those 60 heartbreakingly pointless visits by Haringey's social workers? What was their expert training for? What did their hill of paperwork add up to, if not saving a child?

And in science? A few weeks ago the papers were full of physicists crowing about their project to create a black hole under Switzerland that would unlock the secrets of the Universe. But the only black hole created thus far has been the deafening silence when their much-hyped particle accelerator spluttered and died like a clapped-out Morris Minor on a cold morning. I don't underestimate the importance or mega-complexity of what they are trying to do. But I do question the wisdom of kicking up such a hullabaloo before the experiment even began. More egg on expert faces. More humble pie force-fed in the glare of the world's media.

Even in the inconsequential world of light entertainment, it seems, experts are now doomed to weekly humiliation. I am referring, of course, to the sturdy, not to say stolid, progress of John “Dashing White” Sergeant through the rounds of Strictly Come Dancing - propelled on a wave of “sod the experts” public fervour in the teeth of outraged opposition from the judges.

A trivial matter? Perhaps. Yet as any cultural critic will tell you, usually through gritted teeth, the Sergeant Syndrome is typical of what's going on right across the cultural world. “Give the majority what it wants” is now the overriding mantra in all the arts, especially on TV. It far outweighs notions of excellence, innovation or adventure. Experts are ridiculed as elitist or “out of touch”. Teenage bloggers get as much attention and respect as learned scholars. Quality is counted only in ratings or box-office takings.

Far more than 9/11, or the financial meltdown, or the rise and rise of China, the decline and fall of the expert in public esteem strikes me as the most significant aspect in which the 21st century thus far differs from the 20th. Fifty years ago, people generally felt that only by specialising - fragmenting business, cultural and intellectual life into a million sub-sects of a thousand different disciplines - could humanity keep tabs on an increasingly mind-boggling world. The days when a reasonably bright, curious adult could grasp and contextualise every new complexity in science, culture, politics, exploration and medicine were thought long past. Hence the phrase “Renaissance Man”. The only way that humanity could progress, it was believed, was leadership by experts.

How radically that has changed! The internet has been the prime driving force, spreading the pathetic illusion that all knowledge (and therefore all wisdom) is accessible to everybody. But it's not the only one. Almost as strong is the new belief that everyone's opinion, on every subject, is equally valid - whether that opinion is well informed or crassly ignorant. Deference to authority is dead, even where that authority is based on a lifetime of experience.

Alongside that has grown up a sentimental, Tolstoyian belief that if enough “decent ordinary people” think that something is correct or incorrect, then it must be so. And finally, we've had 11 years of the most meddlesome government in British history, using its democratic mandate to impose ruthless, top-down directives on basically honourable professionals serving the public - such as doctors and teachers. The result? Yet more devaluation of experts in the eyes of the public.

I'm all for democracy and the empowerment of ordinary people. But there must be limits. How long before surgeons have to seek an audience-vote from TV viewers on which operating procedure to use? Or airline pilots have to take a straw-poll among passengers on whether they should use the north or south runway at Heathrow? High-and-mighty experts must be kept in check. But the 21st century is in danger of being the first era in history to value mass mediocrity and water-cooler chit-chat over individual genius, expertise, courage and leadership.

Yes, the experts sometimes get things badly wrong. There are thousands of dazed former bankers wandering aimlessly round Canary Wharf who can attest to that. But if we stop trusting people who are wiser and better informed than us, the world will regress to the Dark Ages. We have to give the experts another chance.

Except, of course, on Strictly Come Dancing.

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