In today’s world, everyone predicts the future. We don’t think of it in that way, of course, but we do. If you go grocery shopping for special pasta to entertain friends on the coming weekend, you’re essentially predicting the future — that you and they will be there and healthy and will enjoy a pasta dinner. Businesses that plan next year’s product line are making predictions about the future. Making contributions to a retirement plan is another form of prediction. In a way, so even is voting for a political candidate. Science fiction writers try to make a living by predicting the future in a fashion that is, hopefully, both intriguing and enjoyable. Economists make their living by trying to predict economic trends.

Most of this kind of prediction is based on extrapolation, on taking existing knowledge and trends and merely extending these trends into the future. Such past-based extrapolation can at times be not only inaccurate, but extremely dangerous, as has been the case with the business and economic types who predicted that good economic times, ever-rising housing and stock prices, and enormous personal deficit financing could continue indefinitely.

Extrapolation can be very effective, if used cautiously, because technology and semi-basic human social patterns normally do not change that quickly, and it’s usually years, if not decades, before “new” technology is fully deployed and adopted throughout society. In addition, most changes are either incremental or cosmetic. For example, most western men wear trousers of some sort most of the time, and it’s been almost two centuries since trousers replaced breaches and stockings. In industrialized nations, the internal combustion engine powers most surface ground transport and has for almost a century. And in most of the world, women remain largely subject to male control and oversight, and in the rest of it, most men — and some women — are resisting further changes in the balance of power between the genders. For all the claims about human adventurism, on balance, we’re a conservative species, and that makes biological sense… until or unless or environment changes radically.

The problem with this mental conservatism is that, when the future cannot be accurately predicted on the basis of extrapolation from past experience, most people, including experts, tend to get it wrong. Conservatism and experience have combined in most people so that for years, the majority tended to be skeptical of global warming and the possible speed of climate change. Many still are, even though the latest measurements of arctic ice and glacier melting in Greenland and Antarctica indicate that the “radical” estimates of the effects on the oceans were far too conservative. The same thing happened with last year’s financial melt-down. But attempts to predict massive and radical change can be equally wrong. Forty years ago, most “experts” were convinced that space travel would be commonplace — and yet, it’s been something like 37 years since any human being even stood on the Moon. And for all the predictions of an “information singularity” or “spike,” it still hasn’t occurred.

As both a writer and as an economist, I’d love to be able to predict accurately beyond the extrapolated future, and so would many, many others, but few ever have, successfully, and perhaps, in some ways, that’s for the best. Cassandra could prophesy beyond the expected, according to Greek myth and the playwright Aeschylus, but her curse was that no one ever believed her, especially when she warned the Trojans against bringing the wooden horse into Troy.