Truth-commitment and constitutional choice

This paper develops a Calculus of Consent -inspired model that focuses on how strongly citizens believe there are moral truths in politics. This truth-commitment is treated as an environmental parameter that shifts external-cost and decision-cost schedules while maintaining the contractarian objective of minimizing their sum. Two results follow. First, the optimal threshold tightens when truth-commitment steepens external costs relative to decision costs and loosens in the reverse case; under a plausible configuration, higher truth-commitment implies stricter rules. Second, even at the optimal rule, the minimized sum of external and decision costs weakly increases whenever truth-commitment raises either component at a fixed rule. The analysis is agnostic about the existence of political moral truth. An interpretive section situates these results in Buchanan’s procedural liberalism under moral anti-realism and explains why popular belief in moral truth tends to elevate the costs of collective organization, providing a contractarian rationale for his skepticism. Extensions sketch how consensus and conviction operate as orthogonal channels, how rights can substitute for higher thresholds, how heterogeneous truth-commitments aggregate, and how perception shifts tied to truth-commitment can distort observed rules. The paper brings metaethical beliefs into the positive theory of constitutional choice, providing a tractable formal account of how truth-commitment shapes optimal rules and the costs of collective organization.