Found via Farnam Street.
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.