Several mathematicians and physicists have made this same argument. Primarily, their argument boils down to two principles: chaos and complexity. The chaotic argument being that any small difference in initial conditions will have a major effect on the end result. The complexity argument being that many small interactions can lead to unpredictable (literally speaking) macroscopic results. Stuart Kauffman has written extensively on the complexity of the economy, and I would recommend his writings to anyone interested in complexity theory.

I think today's unemployment numbers speak to the unpredictability of the economy. First we heard that unemployment wouldn't get above 8%. Then it hit ~10% and all we heard is that it was going to stay there for 2 or 3 years. Now its back to 8.5% and all the economists are making new (useless) predictions. Havel was a genius; I'm glad he could state in an accessible way what many people can only describe in numbers.