Like many major revolutions in history, the East European Revolution of 1989 caught its leaders, participants, victims, and observers by surprise. This paper offers an explanation whose crucial feature is a distinction between private and public preferences. By suppressing their antipathies to the political status quo, the East Europeans misled everyone, including themselves, as to the possibility of a successful uprising. In effect, they conferred on their privately despised governments an aura of invincibility. Under the circumstances, public opposition was poised to grow explosively if ever enough people lost their fear of exposing their private preferences. The currently popular theories of revolution do not make clear why uprisings easily explained in retrospect may not have been anticipated. The theory developed here fills this void. Among its predictions is that political revolutions will inevitably continue to catch the world by surprise.

A feature shared by certain major revolutions is that they were not anticipated. Here is an explanation, which hinges on the observation that people who come to dislike their government are apt to hide their desire for change as long as the opposition seems weak. Because of this preference falsification, a government that appears unshakeable might see its support crumble following a slight surge in the opposition's apparent size, caused by events insignificant in and of themselves. Unlikely though the revolution may have appeared in foresight, it will in hindsight appear inevitable because its occurrence exposes a panoply of previously hidden conflicts.

An availability cascade is a self-reinforcing process of collective belief formation by which an expressedperception triggers a chain reaction that gives the perception increasing plausibility through its rising availability in public discourse. The driving mechanism involves a combination of informational and reputational motives: Individuals endorse the perception partly by learning from the apparent beliefs of others and partly by distorting their public responses in the interest of maintaining social acceptance. Availability entrepreneurs-activists who manipulate the content of public discourse-strive to trigger availability cascades likely to advance their agendas. Their availability campaigns may yield social benefits, but sometimes they bring harm, which suggests a need for safeguards. Focusing on the role of mass pressures in the regulation of risk associated with production, consumption, and the environment, Professors Timur Kuran and Cass R. Sunstein analyze availability cascades and suggest reforms to alleviate their potential hazards. Their proposals include new governmental structures designed to give civil servants better insulation against mass demands for regulatory change and an easily accessible scientzfic database to reduce people S dependence on popular (mis)perceptions.

Although a millennium ago the Middle East was not an economic laggard, by the 18th century it exhibited clear signs of economic backwardness. The reason for this transformation is that certain components of the region's legal infrastructure stagnated as their Western counterparts gave way to the modern economy. Among the institutions that generated evolutionary bottlenecks are the Islamic law of inheritance, which inhibited capital accumulation; the absence in Islamic law of the concept of a corporation and the consequent weaknesses of civil society; and the waqf, which locked vast resources into unproductive organizations for the delivery of social services. All of these obstacles to economic development were largely overcome through radical reforms initiated in the nineteenth century. Nevertheless, traditional Islamic law remains a factor in the Middle East's ongoing economic disappointments. The weakness of the region's private economic sectors and its human capital deficiency stand among the lasting consequences of traditional Islamic law.