Professors McGinnis and Rappaport propose a new theory of the Constitution: supermajoritarianism.   A constitutive thesis maintains that the important processes of government, from treaty-making to legislating, are supermajoritiarian rules of varying strictness; as a normative matter, it is argued that such rules are attractive because they often improve the outputs of government. A formation thesis asserts that the Constitution is formed and amended by strict supermajority rules.  The authors classify supermajority rule as a distinctive American innovation in the science of constitutionalism, and suggest that supermajoritarian underpinnings strongly support an originalist approach to constitutional interpretation.