Skin in the Game: Hidden Asymmetries in Daily Life

by Nassim Nicholas Taleb

ERGODICITY To take stock: a situation is deemed non-ergodic when observed past probabilities do not apply to future processes. There is a “stop” somewhere, an absorbing barrier that prevents people with skin in the game from emerging from it—and to which the system will invariably tend. Let us call these situations “ruin,” as there is no reversibility away from the condition. The central problem is that if there is a possibility of ruin, cost-benefit analyses are no longer possible. Consider a more extreme example than the casino experiment. Assume a collection of people play Russian roulette a single time for a million dollars—this is the central story in Fooled by Randomness. About five out of six will make money. If someone used a standard cost-benefit analysis, he would have claimed that one has an 83.33 percent chance of gains, for an “expected” average return per shot of $833,333. But if you keep playing Russian roulette, you will end up in the cemetery. Your expected return is … not computable.