And not just for economists.

Think of the weather. Forecasts are often wrong for tomorrow, and almost always wrong for next week. Nobody would think of asking a forecaster for next year's weather--but economists are routinely asked to forecast next year's GDP growth.

Or consider engineers. Not usually considered forecasters, but when they build a building they are, in effect, forecasting that it will not fall down. And they are pretty good--not perfect, as buildings (bridges, dams, etc) to fail from time to time because an engineer made what could be called a forecasting error. How do engineers do it? Bigger brains, perhaps? No. They typically build in huge safety buffers--100 percent or more is typical for a bridge. Well, if economists could forecast next year's GDP with that sort of error, they would never be wrong (and would never be useful, either).

Or consider stock market fund managers, often seen on Business News forecasting the markets (Louis Rukyser used to have his forecasts of where the Dow Jones would be in a year--routinely exposing the forecasters to the ridicule they deserved). Again, no good.

Is there anybody who can forecast the future?

The only case I can think of is astronomers, who for thousands of years have been able to accurately forecast the position of the planets, eclipses, sunrises, and the like. Amazingly, they were able to do this even while using what we now know to be incorrect theories (notably, the earth-centered, but nonetheless successful from a forecasting perspective, Ptolemaic model). This is because, it turns out, the movements of the plantets are pretty simple.

And ever since, forecasting has been ruined by this one success.