A week before Christmas, the slow-motion collapse of Argentina suddenly turned swift and violent. Two days of rioting brought down the government and left 31 people dead. All but one were killed by gunfire from shopkeepers and police. Some died while shouting political slogans, others while looting food that they had no money to buy. A few died in their homes, hit by stray bullets, and many were killed outside grocery stores. One woman was shot in front of a Wal-Mart. Most of the demonstrators in the streets were young men--the average age of the dead was 22. What led them to revolt? We will probably never know exactly what combination of popular fury, terrified self-defense, political opportunism, and simple larceny drove the uprising. But consider for a moment the life course of a typical young protestor: Born during the last military dictatorship, he would have lived most of his life under a democracy, but one that offered little more than unemployment and social exclusion. When he...