We have trouble distinguishing a 90 percent chance that the plane will land safely from a 99 percent chance or a 99.9999 percent chance, even though these imply vastly different things about whether we ought to book our ticket. With practice, our estimates can get better. What distinguished Tetlock’s hedgehogs is that they were too stubborn to learn from their mistakes. Acknowledging the real-world uncertainty in their forecasts would require them to acknowledge to the imperfections in their theories about how the world was supposed to behave—the last thing that an ideologue wants to do.
