In recent decades, many economists have advised governments to stabilize, privatize, and liberalize markets. Economists do know how markets work, and they can often predict how mature market economies will respond to certain events and policies. But developing economies lack both mature markets and the institutions that support them—including institutions that define property rights, enforce contracts, convey prices, and bridge gaps between buyers and sellers. These are precisely the institutions that political leaders must establish and then modify as economic growth introduces new problems and opportunities. The work of the Commission on Growth and Development tended to confirm that political leaders play pivotal roles in the success—and the failure—of economic development. As detailed in its publication The Growth Report, the commission closely examined 13 nations whose gross domestic product (GDP) grew at least 7 percent a year for at least 25 years after World War II. In other words, these economies at least doubled in size each decade. Although these high-growth countries used different economic models and political structures and had different resources and histories, their governments followed broadly similar paths. Often ushered in by a crisis, new leadership chose a promising economic model and then stabilized the nation long…