Superforecasting: The Art and Science of Prediction

by Philip E. Tetlock

If we take “highly improbable” to mean a 1% or 0.1% or 0.0001% chance of an event, it may take decades or centuries or millennia to pile up enough data. And if these events have to be not only highly improbable but also impactful, the difficulty multiplies. So the first-generation IARPA tournament tells us nothing about how good superforecasters are at spotting gray or black swans. They may be as clueless as anyone else—or astonishingly adept. We don’t know, and shouldn’t fool ourselves that we do. Now if you believe that only black swans matter in the long run, the Good Judgment Project should only interest short-term thinkers. But history is not just about black swans. Look at the inch-worm advance in life expectancy. Or consider that an average of 1% annual global economic growth in the nineteenth century and 2% in the twentieth turned the squalor of the eighteenth century and all the centuries that preceded it into the unprecedented wealth of the twenty-first.7 History does sometimes jump. But it also crawls, and slow, incremental change can be profoundly important.