University of Chicago Law School Chicago Unbound Journal Articles Faculty Scholarship 1999 Availability Cascades and Risk Regulation Cass R. Sunstein Timur Kuran Follow this and additional works at: https://chicagounbound.uchicago.edu/journal_articles Part of the Law Commons Recommended Citation Cass R. Sunstein & Timur Kuran, "Availability Cascades and Risk Regulation," 51 Stanford Law Review 683 (1999). This Article is brought to you for free and open access by the Faculty Scholarship at Chicago Unbound. It has been accepted for inclusion in Journal Articles by an authorized administrator of Chicago Unbound. For more information, please contact [email protected]. Availability Cascades and Risk Regulation Timur Kuran* and Cass R. Sunstein** An availability cascade is a self-reinforcing process of collective belief formation by which an expressedperception triggers a chain reaction that gives the perception increasingplausibility through its rising availability in public discourse. The driving mechanism involves a combination of informationaland reputational motives: Individuals endorse the perception partly by learning from the apparent beliefs of others and partly by distorting their public re- sponses in the interest of maintainingsocial acceptance. Availability entrepre- neurs-activists who manipulate the content ofpublic discourse-strive to trig- ger 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 environ- ment, Professors Timur Kuran and Cass R. Sunstein analyze availability cas- cades and suggest reforms to alleviate theirpotential hazards. Their proposals include new governmental structures designed to give civil servants better in- sulation against mass demandsfor regulatory change and an easily accessible scientific databaseto reducepeople's dependence on popular (mis)perceptions. * Professor of Economics and King Faisal Professor of Islamic Thought and Culture, Univer- sity of Southern California. ** Karl N. Llewellyn Distinguished Service Professor, Law School and Department of Political Science, University of Chicago. We are grateful to Bruce Ackerman, Nicholas Argyres, Ian Ayres, Mary Anne Case, Tyler Cowen, Richard Epstein, Jack Goldsmith, David Hirshleifer, Saul Levmore, Jane Mansbridge, Bentley Macleod, Vai-Lam Mui, Martha Nussbaum, Linwood Pendleton, Eric Posner, Richard Posner, and Roberta Romano for helpful comments, and to Julie Hupton, Tolga K6ker, Brian Leh- man, and Margaret Peterlin for research assistance. We also received valuable help from partici- pants in legal theory workshops at the Washington University School of Law and Yale Law School, and at economics workshops at George Mason University and the University of Southern Califor- nia. HeinOnline -- 51 Stan. L. Rev. 683 1998-1999 684 STANFORD LAWREVIEW [Vol. 51:683 INTRODUCTION ............................................................................................................... 685 1. COSTLY AVAILABILITY ERRORS .............................................................................. 691 A . Love Canal...................................................................................................... 691 B . Alar ................................................................................................................. 698 C . TWA Flight 800 ............................................................................................... 702 II. INTERPRETING MASS SCARES ABOUT MINOR RISKS ................................................ 703 A . Cognitive Processes........................................................................................ 705 1. Biases and heuristics............................................................................... 705 2. Prospecttheory ....................................................................................... 707 3. The relative acceptability ofrisks ............................................................ 708 4. Beyond individualpsychology: the role ofsocial influences ................... 710 B. InteractionsBetween Social and Cognitive Influences: The Centrality of the Availability Heuristic ............................................................................ 711 III. AVAILAB ILITY CASCADES ....................................................................................... 715 A. The Social Construction ofRisk Judgments and Preferences......................... 717 B . Inform ationalCascades .................................................................................. 720 C. The Distortion ofPublic DiscourseThrough Social Pressures...................... 723 1. Expressive distortions.............................................................................. 724 2. Depth and width ofa public consensus ................................................... 725 3. Social subdivisions and other complexities ............................................. 725 4. Reputationalinsurance ............................................................................ 727 D . Reputational Cascades ................................................................................... 727 E. Socialization and Its Lim its ............................................................................. 729 F. The Self-Reinforcement ofAvailability ........................................................... 730 G . A vailability Campaigns................................................................................... 733 H. Roles of the Media and PoliticalInstitutions .................................................. 735 IV. POPULIST FIRESTORMS AND DEMOCRATIC RISK REGULATION ................................. 736 A . ResistingA vailability Errors........................................................................... 738 B. Social Influences on Cognitive Processes....................................................... 741 C. UndesirableLaw and Policy........................................................................... 742 D . EnduringH arm ............................................................................................... 743 E. UncoordinatedLaw ........................................................................................ 744 V. INSTITUTIONAL SAFEGUARDS AGAINST HARMFUL CASCADES: TOWARD COM PREHENSIVE RATIONALITY .............................................................................. 746 A . Passionsand Constraints................................................................................ 747 B . ProductD efam ation Laws ............................................................................. 749 C . Congress ......................................................................................................... 751 1. Risk oversight.......................................................................................... 752 2. Cost-benefit analysis ............................................................................... 753 D . The Executive Branch ..................................................................................... 754 1. Peerreview .............................................................................................. 754 2. Risk Information Site on the World Wide Web ........................................ 755 3. Office ofInformation and Regulatory Affairs .......................................... 757 E. Courts ............................................................................................................. 758 F. Sum m ary: Revisiting the Cases ....................................................................... 760 CONCLUSIONS AND EXTENSIONS ..................................................................................... 761 HeinOnline -- 51 Stan. L. Rev. 684 1998-1999 April 1999] A VAILABILITY CASCADES 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 heu- ristic, 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.' 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