Maximizing Objective Act-Consequentialism (MOAC) holds that an action is morally right iff no alternative would produce better consequences. One central challenge to MOAC is the Collective Action Problem (CAP), roughly the observation that in some collective decision situations, apparently right individual actions fail to bring about the best possible outcomes. This has been seen as a violation of the Principle of Moral Harmony (PoMH)—the idea that adequate moral theories should guarantee that their adherents collectively produce the best achievable world.

I argue that this critique misdiagnoses the problem: rather than generating incorrect moral assessments, MOAC theories are deontically incomplete, i.e., they fail to generate any (non-conditional) deontic assessments in the relevant class of collective decision situations. CAP, then, is the result of the consequentialist attempt to obscure its own deontic incompleteness.

To address this nexus of problems holistically, I propose a Multi-Agent Criterion of Rightness (MA-CoR), which extends MOAC using game-theoretic principles and mixed strategies to determine morally right actions in collective contexts. By addressing CAP without compromising MOAC’s core commitments, this approach offers a structurally robust conservative extension of the established consequentialist framework for handling collective moral decision-making, transforming an apparent weakness of MOAC into a comparative advantage.