many organizations, of assigning people the task of playing devil's advocate-of making the strongest possible case against a proposed course of action. In the United States, the President is required to ensure that no single political party dominates important agencies, including the Federal Trade Commission, the Securities and Exchange Commission, the Nuclear Regulatory Commission, the National Labor Relations Board, and the Federal Communications Commission. These diversity-building practices counteract the human tendency to conformity. They protect disclosure and dissent. They increase the likelihood that more information will emerge, to the benefit of all.

The point holds during both war and peace. A high-level official during World War 11, Luther Gulick, attributed the successes of the Allies, and the failures of Hitler and the other Axis powers, to the greater ability of citizens in democracies to scrutinize and dissent and hence to improve past and proposed courses of action." Dissent and scrutiny were possible because skeptics were not punished by the law and because informal punishments, in the form of social pressures, were relatively weak. I will suggest that an understanding of group influences and their potentially harmful effects casts new light on a remarkably wide range of issues, including feuds, extremism, terrorism, and war; the institutions of the American constitution; corporate failure and success; the importance and nature of free speech; what is good, and what is bad, about freedom of association; both compliance and noncompliance with law; the value of diversity on the federal judiciary; the (uncomfortably?) close relationship between public opinion at any given time and the meaning of the Constitution at any given time; and the case for affirmative action in higher education.

In a way, my emphasis on dissent goes against the grain of contemporary political theory. In recent decades and more, the emphasis has been on the need for consensus. To take the most prominent example, John Rawls stressed the value of an "overlapping consensus" among citizens who disagree on the most fundamental


issues. I? At a more practical level, many people have bemoaned "adversariallegalism" in American culture, urging that Americans tend to solve their problems through legal contest rather than by searching for consensual solutions. 18 Nothing here is meant to take issue with Rawls or to support adversarial legalism. But the emphasis on agreement and consensus has missed a great deal. We have, I believe, given far too little attention to the dangers of conformity and agreement itself.

Two Influences and Three Phenomena

Throughout I focus on two factors that influence individual belief and behavior. The first involves the information conveyed by the actions and statements of other people. If a number of people seem to believe that some proposition is true, there is reason to believe that that proposition is in fact true. By a large margin, most of what we think comes not from firsthand knowledge but from what we learn from what others do and think. This is true even though they too may be merely following the crowd. When people are responding to the information conveyed by what others do, we have a distinctive kind of conformity. Of course, some people have more influence than others. We are especially likely to follow those who are in positions of authority, who have special expertise, who seem most like us, or whom we otherwise trust.

The second influence is the pervasive human desire to have the good opinion of others. If a number of people seem to believe something, there is an incentive not to disagree with them, at least not in public. The desire to maintain the good opinion of others breeds conformity and squelches dissent, especially but not only in groups that are connected by bonds of affection. Those bonds can therefore impair group performance. We shall see that close-knit groups, discouraging conflict and disagreement, often do badly because of this type of conformity. The problem is that people are failing to disclose what they know and believe.