Nassim Taleb: Throw Out the Probability Models

Found via Farnam Street.

After the events that started in 2007 and the subsequent reactions by economists, anyone who takes the current economics establishment seriously needs to spend time in a sanatorium.

This does not mean we should write off the entire body of knowledge. By now, we can see what works and what does not work. Simply, a certain class of consequential rare events, what I’ve called “black swans,” are not predictable and their probabilities unmeasurable, so anything that relies on a computation of the probability of these events should go out of the window. Now. Such models induce fragilities and bring harm. We're better off with no model than with a defective model, something people understand intuitively, but they tend to forget when they don’t have “skin in the game.” If you are a passenger on a plane and the pilot tells you he has a faulty map, you get off the plane; you don’t stay and say “well, there is nothing better.” But in economics, particularly finance, they keep teaching these models on grounds that “there is nothing better,” causing harmful risk-taking. Why? Because the professors don’t bear the harm of the models.