When I was a boy I always assumed that economists knew their stuff so I hurt my cerebellum trying to understand theories surrounding production, distribution, consumption, inflation, recession, the law of supply and demand, Adam Smith, JM Keynes, Karl Marx, Thatcherism, laissez faire, market forces, interventionism, the common market, five-year plans and much else. Now, I look back and think what a strange child I must have been.

Strange and heartbreakingly naive, that is. About a couple of centuries ago, Thomas Carlyle called economics the "dismal science" and mocked Reverend Malthus's theory that lack of food production and a growing population would lead to mass starvation. Which makes Carlyle sound likeable until you discover that he argued that slavery was a good thing in that it regulated labour markets. Looking back, we can say with some confidence that both these confident fellows were wrong in these particular views (although some say the good Reverend could yet be proven correct).

More recently, Nigel Lawson, once a finance journalist, managed to make such a mess of the UK economy that his boss, Margaret Thatcher, drafted in her own special advisor. Lawson now advises us that climate change is a myth. And Gordon Brown hailed the end of boom and bust -- not very long before a bust.

Both Tories and Labour claimed "light touch" legislation had been the making of London as capital of the world's largest financial institutions and a boon for British taxpayers. Now we tax payers own many of the world's largest institutions, all of which employed large numbers of economists to control risk.

Most economists -- and everybody is an economist these days -- are wrong if you go back and look at the tundra separating prediction from reality. Our own Chancellor was mocked for predicting an emergence from recession this year; we seemed to general surprise to be emerging... and then surprised economists by sinking back.

Of course, someone gets it right. Vince Cable is lauded as the man who predicted the recession but it's not at all obvious that his call wasn't merely a fluke. To establish his expertise, he would have to forecast correctly the next boom and bust. And he can't do that because economics is dependent on a huge number of factors, supplemented by a stream of new-arrival factors, all of which have weightings that tend to move up and down with the changing of the seasons and the tides of the sea, never mind the price of pork bellies.

If I'm unconvinced by economists, I'm equally unconvinced by those who predict changes in technology markets. That's because, just like economics, technology is an uncertain, hugely dynamic field. So nobody thought Pointcast would fail, nobody saw Twitter or Facebook coming. Even the web itself only popped up on futurologists' lists shortly after it stared them in the face.

Industry watchers talk of the importance of watching trends such as cloud computing, capacity planning and becoming proactive about new developments. The truth is we haven't got a clue what will happen next. We might be better of sticking to what we do best: whistling in the dark and making sure we move PDQ when we need to.