Expectations and Informal Rules in Coalition Formation

Why do informal rules emerge alongside—and at variance with—the formal constitutional constraints that shape bargaining over coalition governments? The presence of informal rules at odds with formal rules appears as an anomaly within both institution-free and institution-focused theories of coalitions. The author argues that politicians create informal rules in order to alter formal institutions that do not function to their benefit. The costs of a formal change in institutions offer incentives to politicians to invent informal rules as alternatives to such change, and repeated interactions teach politicians what to expect and then invent. The author's emphasis on the manipulability of rules echoes long-standing themes in the study and practice of politics.