In the 1980s, it seemed that computers held the key to economic forecasting. With large models and sufficient processing power, predictions would become more and more accurate.
This dream did not last long. We now understand that economies are complex, dynamic, non-linear systems in which small differences to initial conditions can make large differences to final outcomes – the proverbial flapping of a butterfly's wings that causes a hurricane.
So economic crystal ball-gazing remains unscientific. The trend is the forecaster's friend. Extrapolation assumes that the future will be like the past, only more so. We project current preoccupations – the rise of China and India, global terror, climate change – with exaggerated speed and to an exaggerated degree.
We forget that our preoccupations change. The people who worry about these issues today would 20 years ago have worried about the coming economic hegemony of Japan and the cold war. These issues were resolved in ways that few predicted.
It is a safe prediction – and the only one I shall make – that the topics that grab our attention 20 years from now will differ from those that consume us today and, if anyone has guessed what they are, it is only by accident. The future is unknowable. As Karl Popper observed, to predict the creation of the wheel is to invent it. To anticipate a new political force or economic theory, or even a new product, is to take the main step in bringing it into being.