Although supermajority rules originally emerged as an alternative to unanimity to address the risk of human fallibility, in the modern era, supermajority rules are typically used to remedy the risks associated with unfettered majority decision making. Drawing on the work of Condorcet, we have seen that the strongest justification for supermajority rules is to bias decision making to reduce the probability of serious moral or epistemic error. Condorcet developed two key arguments on behalf of supermajority rules. First, supermajority rules bias our decisions when consequence of acting wrongly is much greater than not acting at all; when one option (acquittal) is clearly preferable to an erroneous choice (false conviction), as in Condorcet’s example of the jury; or perhaps when a rule is proposed that would generate inequality among the citizens. Second, because more individuals must be persuaded, supermajority rules prevent hasty decision making and ensure full consideration of reasons.

To mitigate such risks, of course, is a central goal of constitutionalism. One key aim of constitutionalism is to introduce a strong status quo bias into democratic decision making. This is, first, because stability is intrinsically desirable, as it affords the security of expectations. Second, a status quo bias enables ordinary political life, including legislation, to operate without constant renegotiation of the terms. An unstable framework hinders political and economic development, and potentially generates interminable conflict over the core structures of politics. But constitutionalism also seeks to reduce familiar normative risks: the threat of “tyranny of the majority,” of violations of the rights of minorities in particular, of a partisan majority acting to alter the terms of the political arrangement to enhance its reelection prospects, and so on.