Conformity CONFORMIT Y The Power of Social Influences Cass R. Sunstein NEW YORK UNIVERSITY PRESS New York NEW YORK UNIVERSITY PRESS New York www.nyupress.org © 2019 by New York University All rights reserved References to Internet websites (URLs) were accurate at the time of writing. Neither the author nor New York University Press is responsible for URLs that may have expired or changed since the manuscript was prepared. Library of Congress Cataloging-in-Publication Data Names: Sunstein, Cass R., author. Title: Conformity : the power of social influences / Cass R. Sunstein. Description: New York : New York University Press, 2019. | Also available as an ebook. | Includes bibliographical references and index. Identifiers: LCCN 2018041768| ISBN 9781479867837 (cl ; alk. paper) Subjects: LCSH: Sociological jurisprudence. | Law—Social aspects. | Conformity. | Social influence. Classification: LCC K370 .S83 2019 | DDC 340/.115—dc23 LC record available at https://lccn.loc.gov/2018041768 New York University Press books are printed on acid- free paper, and their binding materials are chosen for strength and durability. We strive to use environmentally responsible suppliers and materials to the greatest extent possible in publishing our books. Manufactured in the United States of America 10 9 8 7 6 5 4 3 2 1 Also available as an ebook Contents Acknowledgments vii Preface ix Introduction: The Power of Social Influences 1 Chapter 1: How Conformity Works 11 Chapter 2: Cascades 35 Chapter 3: Group Polarization 79 Chapter 4: Law and Institutions 101 Conclusion: Conformity and Its Discontents 147 Notes 153 Index 173 About the Author 183 v Acknowledgments This short book has traveled a long and winding road. In early 2003, I delivered the Oliver Wendell Holmes, Jr., Lec- tures at Harvard Law School, under the title “Conformity and Dissent.” With the help of the comments I received dur- ing and after the presentation, the lectures were reoriented, expanded, and transformed into a book, Why Societies Need Dissent, published by Harvard University Press in late 2003. There is of course a significant overlap between the original text and that book. But I retained a fondness for the original lecture text, which was not only significantly shorter but also more focused, less polemical, and a bit less preachy— and also more quizzical, and in some ways (I like to think) more enduring. As of this writing, there is mounting worldwide attention to the problem of conformity, and also to associated questions about identity, extremism, cascades, polarization, and diversity. This book is a contemporary version of the original text, with a new preface and a variety of changes, mostly for updating and clarity of exposition. I am acutely aware that with respect to the underlying social science, there have been significant develop- ments since 2003. I have done my best to summarize the lead- ing developments and to avoid relying on controversial claims and findings, though the field continues to progress. vii Acknowledgments It took a village. For valuable discussions and comments, I am grateful to Jacob Gersen, Reid Hastie, David Hirshleifer, Christine Jolls, Catharine MacKinnon, Martha Nussbaum, Susan Moller Okin, Eric Posner, Richard Posner, Lior Stra- hilevitz, Edna Ullmann-M argalit, and Richard Zeckhauser. Special thanks to my agent, Sarah Chalfant, for help and sup- port, and to my editor, Clara Platter, for valuable suggestions throughout and above all in connection with the preface. Andrew Heinrich and Cody Westphal provided excellent re- search assistance. viii Preface Conformity is as old as humanity. In the Garden of Eden, Adam followed Eve’s lead. The spread of the world’s great religions is partly a product of conformity. Books remain to be written on this topic, with special attention to Christianity, Islam, and Judaism.1 Generosity and kindness, concern for the vulnerable, considerateness, protection of private prop- erty, respect for human dignity—a ll of these are fueled by conformity, which provides a kind of social glue.2 Conformity also makes atrocities possible. The Holocaust was many things, but it was emphatically a tribute to the im- mense power of conformity. The rise of Communism also re- flected that power. Contemporary terrorism is not a product of poverty, mental illness, or a lack of education. It is a prod- uct, in large part, of the pressure that some people put on other people. That pressure has everything to do with con- formity. When people of one political party march together, develop dogmas and rages, and ridicule people of another political party, conformity is at work. In its worst forms as well as its best, nationalism is fueled by conformity. As we shall see, the idea of conformity is far more interest- ing and less simple than it seems. But two ideas capture much of the territory. First, the actions and statements of other people provide information about what is true and what is ix