From Private Good to Public Good: The System Logic of Social Cooperation—A System Logic Framework for Cooperation, Institutional Alignment, and Civilizational Evolution

The first five papers in the System Logic series established systemic adequacy, boundary and time, local optimization and systemic failure, feedback and systemic correction, and the Systemic Impact Ledger as core tools for evaluating judgments and actions in open systems. Together, they raise a central question: in a multi-agent, multi-level, and multi-temporal system, how do actions aimed at individual self-interest transform into outcomes beneficial to larger systems, and how do they instead transform into harm to those systems? This paper proposes a System Logic framework for analyzing the transition from private good to public good. It distinguishes private good from public good but refuses to oppose them absolutely. It argues that private good is the reasonable tendency of individual system self-maintenance and the starting point of value, while public good is the path to realizing private good at larger system boundaries. The evolution from private good to public good is not a negation of private good but its expansion and elevation at larger spatiotemporal scales. This expansion is achieved through four mechanisms: kin selection, reciprocal altruism, reputation mechanisms, and institutional alignment. The unity of private and public good requires four conditions: boundary expansion, temporal extension, institutional alignment, and cultural internalization. When these conditions are met, private good pursuit can be realized through public good pathways, forming positive-sum cooperation; when they are absent, private good pursuit may be realized through public evil pathways, forming negative-sum conflict. The paper distinguishes five levels of public good—family, community, nation, humanity, and ecology—and analyzes the psychological foundations, social conditions, pathological forms, and the "detour" strategy of public good evolution. It demonstrates the framework through cases from market exchange, public goods provision, organizational cooperation, social governance, environmental protection, public health, educational equity, and international climate cooperation. Finally, it discusses theoretical boundaries and falsifiability conditions, providing foundations for subsequent research on institutional adaptation and civilizational risk.