Authors: Kuper & Kuper
Summary: The entry defines the term, and distinguishes between empirical and theoretical approaches to studying the concept. Coalitions are groups of people who band together to accomplish some goal.
The empirical approach to their study consists of establishing which individuals or groups work together, usually in some institutional setting. Alliance formation is another example of the empirical tradition; all forms of government require coalitions to obtain and retain power, and empirical researchers investigate what coalitions in fact exist.
Theoretical work on coalitions attempts to solve various problems. One such problem concerns the size of winning coalitions. Riker, for instance, argued that in cases of complete information, coalitions would be of minimal winning size, so that the pay-off to the coalition would be split up among the fewest possible members. Another theoretical problem concerns the basis on which coalitions form. The most frequent hypothesis is that coalition formation depends on shared values, but that a variety of other factors such as friendship or past experiences could influence this process. A third theoretical problem concerns the distribution of pay-offs among members of the winning coalition. It might be, for instance, that different coalition members are rewarded with different kinds of pay-offs--for example, one party might obtain legislation that it thinks is important, while another might receive visibility in the next election campaign). A final theoretical problem concerns the duration of coalitions.