WHY do certain dictators survive while others fall? Throughout history, downtrodden citizens have tried to throw off the yoke of their oppressors, but revolutions, like those sweeping through the Arab world, are rare.

Despotic rulers stay in power by rewarding a small group of loyal supporters, often composed of key military officers, senior civil servants and family members or clansmen. A central responsibility of these loyalists is to suppress opposition to the regime. But they only carry out this messy, unpleasant task if they are well rewarded. Autocrats therefore need to ensure a continuing flow of benefits to their cronies.

If the dictator’s backers refuse to suppress mass uprisings or if they defect to a rival, then he is in real trouble. That is why successful autocrats reward their cronies first, and the people last. As long as their cronies are assured of reliable access to lavish benefits, protest will be severely suppressed. Once the masses suspect that crony loyalty is faltering, there is an opportunity for successful revolt. Three types of rulers are especially susceptible to desertion by their backers: new, decrepit and bankrupt leaders.

Newly ensconced dictators do not know where the money is or whose loyalty they can buy cheaply and effectively. Thus, during transitions, revolutionary entrepreneurs can seize the moment to topple a shaky new regime.