"1. Institutions shape politics. The rules and standard operating procedures that make up institutions leave their imprint on political outcomes by structuring political behavior. Outcomes are not simply reducible to the billiard-ball interaction of individuals nor to the intersection of broad social forces. Institutions influence outcomes because they shape actors' identities, power, and strategies. 2. Institutions are shaped by history. Whatever other factors may affect their form, institutions have inertia and "robustness." They therefore embody historical trajectories and turning points. History matters because it is "path dependent": what comes first (even if it was in some sense "accidental") conditions what comes later. Individuals may "choose" their institutions, but they do not choose them under circumstances of their own making, and their choices in turn influence the rules within which their successors choose."