Social interaction involving groups is sometimes easy to understand when all the participants behave as if they were a collective individual, as at sports events where fans are cheering for one team or the other, or at political rallies where all are exhibiting a common candidate preference. But often individuals make decisions in response to the environment they perceive or anticipate, and in doing so alter that environment, for example when different racial groups enter previously segregated neighborhoods, or when people in poor health join insurance groups that had covered people without known health risks. In these cases individual choices might influence choices made by other individuals and alter the group status. It is useful to understand the group dynamics of such cases.
To explain how individual decisions operate in the aggregate, when they are combined with the decisions of others making related decisions, Schelling wrote a book entitled Micromotives and Macrobehavior.1 Micromotives are the individual’s decisions, and the macrobehavior is the resulting conduct of the many decisions in the aggregate. Schelling’s book features easily understood models, or social studies constructs, that demonstrate the underlying features of many such situations.
Models simplify situations by embodying the relationships involved in some transparent manner and make the phenomenon that is taking place more easily recognized. They may help make aggregate behavior easier to predict and to encourage good outcomes or prevent negative ones. The outcomes of aggregate decisions may not always reflect individual preferences, though policy planners sometimes assume that they do. Is the fact that segregated neighborhoods continue to exist proof that people are prejudiced or desire to live in segregated neighborhoods? It would be jumping to an unsubstantiated conclusion to make such an assumption based on the result of existing segregation alone, as a Schelling model presented in Chapter 18 will demonstrate.
Models in social science are often “first approximations” presenting a simple underlying structure for a situation that can be elaborated on to represent more accurately what one hopes to understand. A block of wood sliding across the floor could be a first approximation model for an automobile. The first approximation model of a national economy might be presented as a formula that illustrates the interaction of consumption, government spending, investment, and net exports. This basic national economy model can be elaborated on to include more and more factors,