Abstract: The more complex the political institutions, the more stable and socially efficient the outcomes will be. This book develops an extensive analysis of this relationship. The discussion is theoretical, historical, and comparative. Concepts, questions, and insights are based on social choice theory, while an empirical focus is cast on about 40 countries and a few international organizations from late medieval times to the present. Political institutions are conceived here as the formal rules of the game, especially with respect to the following issues: who can vote, how votes are counted, and what is voted for. Complexity signifies that multiple winners exist, as in plural electorates created by broad voting rights, in multi-party systems based upon electoral systems of proportional representation, and in frameworks of division of powers between the executive and the legislative or between the central government and noncentral units. The efficiency of outcomes is evaluated for its social utility, which is to say, the aggregation of individuals’ utility that is obtained with the satisfaction of their preferences. This is a book that emphasizes the advantages of median voter's cabinets and presidents, divided government, and federalism. Pluralistic democratic institutions are judged to be better than alternative formulas for their higher capacity of producing socially satisfactory results.

Keywords: division of powers, electoral systems, federalism, institutions, median voter, parliamentarism, presidentialism, social choice, social utility, voting rights