Before we can develop a theory of politics we must have a framework for representing individual preferences. Individual human beings form the body politic, no matter what the society or political system under consideration looks like. Interest groups, parties, nations, legislatures, and politburos consist of individuals who shape the character of these institutions. Even the procedures, traditions, and constitutions that guide and regulate people's choices within collectivities are the product of individual decisions. The maintenance and longevity of these things, moreover, depend on the willingness of people to tolerate outcomes under them compared with the outcomes wrought by revolution, political activism, and alternative procedures. A framework that focuses solely on individual choice is inadequate, however, because people in politics choose in an environment made up of other persons’ choices, and these choices affect and condition each other. By and large, “nature” in Chapter 1 is neither a deity nor some unthinking creature, but other persons who pursue their goals. A theory that does not incorporate this reality cannot say anything about what political scientists study.

Our central concern is the study of public outcomes such as the laws and regulations that legislatures authorize, the policies that victorious election candidates implement, the interpretation of laws that courts render, the actions that public bureaucrats take under the authority that legislators and executives give them, and the decisions to go to war or the conditions of peace that nations establish. But this chapter seeks to dissuade readers from believing that such outcomes follow in some simple, obvious way from individual preferences. Our argument begins with the observation that institutions mediate between all public outcomes and individual preferences.