Our model is based on the fact that across history, what creates the risk of political instability is the behavior of elites, who all too often react to long-term increases in population by committing three cardinal sins. First, faced with a surge of labor that dampens growth in wages and productivity, elites seek to take a larger portion of economic gains for themselves, driving up inequality. Second, facing greater competition for elite wealth and status, they tighten up the path to mobility to favor themselves and their progeny. For example, in an increasingly meritocratic society, elites could keep places at top universities limited and raise the entry requirements and costs in ways that favor the children of those who had already succeeded.

Third, anxious to hold on to their rising fortunes, they do all they can to resist taxation of their wealth and profits, even if that means starving the government of needed revenues, leading to decaying infrastructure, declining public services and fast-rising government debts.

Such selfish elites lead the way to revolutions. They create simmering conditions of greater inequality and declining effectiveness of, and respect for, government. But their actions alone are not sufficient. Urbanization and greater education are needed to create concentrations of aware and organized groups in the populace who can mobilize and act for change.