The monograph is a generalization of the theory and methodology of comparative political studies in the post-war period in the West. It analyzes the main stages of the history of comparative political science, the essence and problems of comparing the content of empirical theory and models of democracy. A systematic presentation of democracy indices is given. Modern methodological approaches to political comparison are investigated - the theory of rational choice and neo-institutionalism. The possibility of Boolean algebra in the study of democratic processes and systems is being dismantled.