Trained as a physicist, Emanuel Derman once served as the head of quantitative analysis at Goldman Sachs and is currently a professor of industrial engineering and operations research at Columbia University. With "Models Behaving Badly" he offers a readable, even eloquent combination of personal history, philosophical musing and honest confession concerning the dangers of relying on numerical models not only on Wall Street but also in life.

Mr. Derman's particular thesis can be stated simply: Although financial models employ...