Investors have too often extrapolated from recent experience. In the 1950s, who but the most rampant optimist would have dreamt that over the next fifty years the real return on equities would be 9% per year? Yet this is what happened in the U.S. stock market. The optimists triumphed. However,...

Our ability to forecast degrades rapidly the further out we predict. Even if we do manage to accurately forecast an event, the magnitude and consequences of that event usually astonish us. On the rare occasion where we manage to accurately forecast the event, its magnitude and consequences, our...