Availability cascades and risk regulation.

AuthorKuran, Timur

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.

INTRODUCTION

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.(4) Not every member of a society experiencing an informational cascade need be influenced; those with considerable private information may remain unswayed. Under the right conditions, however, many or most of the society's members, potentially even all, will end up with essentially identical beliefs, which may well be fanciful.

Insofar as society is socially fragmented, it may exhibit local informational cascades. A local informational cascade is one limited, for example, to a geographical area, a demographic subgroup, or a core of activists who share a political objective. Local informational cascades are quite common and, as we shall see, potentially quite important.

Like an informational cascade, a reputational cascade is driven by interdependencies among individual choices. It differs, however, in the underlying personal motivations. In the case of a reputational cascade, individuals do not subject themselves to social influences because others may be more knowledgeable. Rather, the motivation is simply to earn social approval and avoid disapproval. In seeking to achieve their reputational objectives, people take to speaking and acting as if they share, or at least do not reject, what they view as the dominant belief. Everyone has had the experience of modifying public statements or actions in order to win praise or avoid censure. If a particular perception of an event somehow appears to have become the social norm, people seeking to build or protect their reputations will begin endorsing it through their words and deeds, regardless of their actual thoughts. As in the informational case, the outcome may be the cleansing of deviant perceptions, arguments, and actions from public discourse. And just as informational cascades may be limited in their reach, there may exist local reputational cascades--self-reinforcing processes that reshape the public pronouncements of particular subgroups without affecting those of the broader group.

Reputational and informational cascades are not mutually exclusive. Ordinarily, they exhibit interactions and even feed on one another.(5) The resulting composite process, which is generally triggered by a salient event, is what we are calling an availability cascade.(6)

Social agents who understand the dynamics of availability cascades and seek to exploit their insights may be characterized as availability entrepreneurs. Located anywhere in the social system, including the government, the media, nonprofit organizations, the business sector, and even households, these entrepreneurs attempt to trigger availability cascades likely to advance their own agendas.(7) They do so by fixing people's attention on specific problems, interpreting phenomena in particular ways, and attempting to raise the salience of certain information. For example, availability entrepreneurs acting on behalf of corporations focus on cases of strikingly large punitive damages awards as a means of building support for tort reform.(8) Likewise, environmental organizations draw attention to apparent disasters (e.g., Love Canal, Chernobyl, Three Mile Island) to support their calls for tighter regulation.(9)

Such availability campaigns often produce social benefits by overcoming public torpor and fueling debates on long-festering though rarely articulated problems. These desirable effects can arise in domains as diverse as economic regulation, identity politics, and social customs. At the same time, availability campaigns sometimes do great harm by producing widespread availability errors.(10) This danger points to the need for institutional safeguards to ensure better priority-setting and fuller use of scientific knowledge. Proper safeguards, which need not entail either "more" regulation or "less" regulation, can save both lives and dollars.

Offering recent examples of availability cascades that have resulted in socially harmful regulatory responses, we shall propose institutional reforms to insulate the government and the legal system against the political pressures generated by harmful cascades. Insofar as the reforms turn out to be effective, they would ensure that when government responds to political pressures, it does so because the underlying problems are serious. Although our proposals are developed with special reference to the tripartite governmental system of the United States, with minor modifications they can be applied to any democratic system. Our analytical framework and policy conclusions carry major implications for both populist and deliberative conceptions of democracy. A central theme in contemporary debates on democracy is that political judgments should reflect much more than a technocratic exercise; these judgments should be based on the facts, to be sure, but also on people's reflective values, including their tolerance for uncertainty. The analysis below is followed by concrete proposals on how these objectives can be advanced.

All of our major illustrations involve availability cascades pertaining to the regulation of risks,(11) a topic especially well-suited to exploring interactions between democracy and law. We hasten to point out, however, that the general framework can be applied to a wide variety of other areas. Among the diverse social transformations that exhibit striking examples of availability cascades are the rise and decline of McCarthyism; the straggle for black civil rights; the student rebellions of the 1960s; the spread of affirmative action and the recent explosion of public opposition to it; the rise of feminism, the anti-tax movement, and the religious right; ongoing campaigns against pornography, hate speech, smoking, health maintenance organizations, and the burning of black churches; the spread of ethnic and religious separatism across the world; the persistence and sudden fall of communism; the global turn toward...

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