Why so much stability? An optimistic view of the possibility of rational legislative decisionmaking

Recent formal models of legislatures have proved that equilibrium outcomes are extremely unlikely without either (1) extreme restrictions upon preferences or (2) constraints upon the agenda. The implication is that constant instability or dictatorial manipulation is the norm in politics. This paper argues to the contrary, that legislatures (and other political processes) are characterized by some regularities, and that equilibrium models are the appropriate technique to use in describing these regularities. Examples from economic theory are used to illustrate this principle. The assumption of equilibrium is methodological, committing the researcher to develop models that have specific empirical implications. Using analogies from the economic theories of general equilibrium, oligopoly, and demand revealing processes, some potentially fruitful means of developing equilibrium political models are described. Assuming that legislators may freely make binding contracts has both empirical and normative advantages. Finally, institutional restrictions on legislative agendas may assure equilibrium. These include ‘constitutional’ rules, agreements to share ‘pork barrel’ projects evenly, limitation of committees to specific policy arenas, and the election of leaders who then determine the voting agenda.