Abstract
This dissertation develops a novel metaethical position called Moral Intersubjectivism. Against the prevailing tendency to theorize morality in individualist terms and within rigid realist/anti-realist dichotomies, it grounds moral truth, authority, and objectivity in intersubjective practice—the socially structured activity of giving and asking for moral reasons. The negative argument identifies a structural error common to nonnaturalist metaethics which conflates constitutive presuppositions of moral deliberation with ontological commitments to stance-independent moral facts. The positive account rests on two pillars. Moral truth is analyzed as indefeasibility under indefinite intersubjective moral inquiry, supported by a systematic framework of epistemic defect-markers. Moral authority is grounded in a recognitive normative order—relations of mutual accountability through which agents acknowledge one another’s standing and hold each other answerable—and carries universal scope through the principle of Recognitive Non-Closure. These two pillars converge: the community of moral inquiry is the community of mutual recognition, and moral truth and moral authority are aspects of a single intersubjective structure. A fourfold taxonomy of moral norms—natural invariants, extended invariants, contested variants, and pluralistic variants—replaces the binary objectivism/relativism framework, explaining moral variance, pathology, and progress as structural features of a graded moral objectivity that is standpoint-invariant without being stance-independent.