The third set of surveyors igo examines found the average American in a very different place. The biologist Alfred Kinsey, a professor at the University of Indiana (naturally), set out to discover how the average American has sex. What he discovered was that the average American was a pervert. That’s not how Dr. Kinsey would have put it, of course. From an unprecedented course of 5,300 interviews, Sexual Behavior in the Human Male, Kinsey’s research team specified how many times their subjects obtained “sexual outlet”: masturbation, nocturnal emission, heterosexual petting, heterosexual intercourse, homosexual outlet, and, yes, “animal contacts.” What they found was that under the existing sex laws, 95 percent of American men were criminals, and that 37 percent of men had had homosexual contact. And that was a result the doctor preferred to find. He was a closet sexual liberationist who believed that enlightened rationality could strike from the earth what he saw as the tyranny of sex laws and norms, rooted in shame, hypocrisy, and ignorance.

But were his findings right? The debate has raged ever since. His underlying methodological flaw was that a person had to be willing to submit to the most probing sexual interview imaginable to show up in the data. As one angry critic charged, “no normal moral man or woman” would ever do that. The critic had a point. People who were comfortable with sex did seem to be over-represented in his sample; as some of Igo’s examples make clear, for many the thought of being interviewed by Kinsey was in itself a sexual thrill. The problem was compounded when Kinsey turned his attention to Sexual Behavior in the Human Female. “Given reigning conventions about female modesty, the idea of women submitting to interviews with the all-male research team was especially unsettling,” Igo notes. “Many concluded that Kinsey’s female interviewees must have been prostitutes, or at the very least seriously maladjusted.”

The American inclination to believe that the American who is typical is for that reason good was about to receive a workout as never before. These people were not “good”—the very fact that they answered Kinsey’s questions was evidence of that. Therefore they could not be typical. How did critics of the study know? They were typical Americans, and they didn’t do any of these things. “I have lived with one woman for 46 years,” wrote one, “and I do not agree with your findings . . . when you show as one magazine reports that 62 percent of adult women practice masturbation.”

Such letters weren’t that different from the letters Gallup got. The vast majority of letter writers, Igo reports, “were troubled that a science claiming to speak for them had never bothered to ask their opinion in the first place.” Kinsey and Gallup, after their fashion, each argued that the average American had a special moral standing. So if you disagreed, you probably weren’t average. Worse, they may have been suggesting that something was wrong with you. Such were the wages of averaging Americans. (No one ever wrote Gallup to complain, “How dare you claim my opinion is in the majority?”) It is a uniquely American problem. Alexis de Tocqueville, after all, was fascinated by the paradox that in this most free of all nations, the one in which self-invention was supposed to be an accepted part of life, demands for conformity were more pervasive than in the unfree nations of Europe. E pluribus unum sometimes means denying that “the many” exist in the first place.

Rick Perlstein is the author of Before the Storm: Barry Goldwater and the Unmaking of the American Consensus. His new book, Nixonland: The Politics and Culture of the American Berserk, 1965-1972, is forthcoming.