In premodern social systems politics was the task of members of privileged social strata who were born into these rights. Modern political systems are based on the universal inclusion of all citizens who participate in politics with equal rights. A political system consists of public roles, performance roles, public opinion, political parties, elections and of institutions such as parliament and government who are staffed on the basis of election results. In contrast to the legal system or the system of science or the system of art, there is no form of knowledge indispensable for the participation in politics. The political system deals incessantly with ever new societal problems, but in political terms it knows nothing about these problems. The polity is a decision system, but not a knowledge system. The essay analyses the structures of political systems resulting from this condition. Among these consequences are the dependence on nonpolitical experts and the acceptance of functionally specialised organisations to whom the polity entrusts decisions which would overtax it. At its core the polity is a system without knowledge which must incessantly be provided with cognitions to be able to operate.