Technocrats claim to know how to solve the social and economic problems of complex modern societies. But this would require predicting how people will act once technocrats impose their policy solutions. Power Without Knowledge argues that people’s ideas, w hich govern their deliberate actions, are too heterogeneous for their behavior to be reliably predicted. Thus, a technocracy of social-scientific experts cannot be expected to accomplish its objectives. The author also shows that a large part of contemporary mass politics, even populist mass politics, is technocratic, as members of the general public often assume that they are competent to decide which policies or politicians will be able to solve social and economic problems. How, then, do “citizen-technocrats” make these decisions? Drawing on political psychology and survey research, the author contends that people often assume that the solutions to social problems are self-evident, such that politics becomes a matter of vetting public officials for their good intentions and strong wills, not their knowledge. Turning to the more conventional meaning of technocracy, the author argues that social scientists, too, drastically oversimplify technocratic realities, but in an entirely different manner. Neoclassical economists, for example, theorize that people respond rationally to the incentives they face. This theory is simplistic, but it creates the appearance that people’s behavior is predictable. Without such oversimplifications, the author argues, technocracy would be seen by technocrats themselves to be chimerical.