Availability Cascades and Risk Regulation
Kuran, Timur, Sunstein, Cass R., Stanford Law Review
An availability cascade is a self-reinforcing process of collective belief formation by which an expressed perception 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 risks 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 scientific database to reduce people's dependence on popular (mis)perceptions.
The purpose of this article is to identify a set of interlinked social mechanisms that have important, sometimes desirable, but at other times harmful effects on risk regulation. The harmful effects range from inconsistent health regulations to mass anxiety about foods with no scientifically confirmed health hazards. The underlying mechanisms help shape the production of law through their effects on legislators, administrative agencies, and courts.
The mechanisms presented below are mediated by the availability heuristic, a pervasive mental shortcut whereby the perceived likelihood of any given event is tied to the ease with which its occurrence can be brought to mind. Cognitive psychologists consider the availability heuristic to be a key determinant of individual judgment and perception. They have demonstrated that the probability assessments we make as individuals are frequently based on the ease with which we can think of relevant examples.(1) Our principal claim here is that this heuristic interacts with identifiable social mechanisms to generate availability cascades--social cascades, or simply cascades, through which expressed perceptions trigger chains of individual responses that make these perceptions appear increasingly plausible through their rising availability in public discourse. Availability cascades may be accompanied by counter-mechanisms that keep perceptions consistent with the relevant facts. Under certain circumstances, however, they generate persistent social availability errors--widespread mistaken beliefs grounded in interactions between the availability heuristic and the social mechanisms we: describe.(2) The resulting mass delusions may last indefinitely, and they may produce wasteful or even detrimental laws and policies.
An availability cascade subsumes two of the special cascades that have recently received considerable attention in the social sciences, though not in law: informational cascades and reputational cascades.(3) An informational cascade occurs when people with incomplete personal information on a particular matter base their own beliefs on the apparent beliefs of others. To be more specific, suppose that the words and deeds of certain individuals give the impression that they accept a particular belief. In response to their communications, other individuals, who lack reliable information, may accept that belief simply by virtue of its acceptance by others. As long as members of the relevant group are heterogeneous along one or more dimensions (e.g., initial personal information, willingness to rely on others for information, timing of social contacts), the transformation of the distribution of beliefs can take the form of a cascade, known also as a bandwagon or snowballing process. …