System Logic: From Formal Validity to Systemic Adequacy—An Evaluative Framework for Judgment, Action, and Long-Term Consequences in Open Systems

Formal logic has long served as the backbone of human reasoning by establishing rigorous standards of validity within closed systems. Yet when reasoning is embedded in open, dynamic, and highly coupled real-world systems, formal validity alone proves insufficient. This paper develops "system logic" as an analytical framework for judgment in complex reality and introduces "systemic adequacy" as its central concept. Systemic adequacy moves beyond isolated concerns with truth values or instrumental efficiency to examine the holistic coordination of judgments and actions within specified systemic boundaries, temporal horizons, and value constraints. Drawing on general systems theory, cybernetics, complex systems science, ethics, decision theory, and institutional analysis, the paper advances a six-element definition of systemic adequacy, articulates five operational principles, and constructs a methodological chain of four systemic stress tests. A structural evaluative profile is proposed to capture systemic adequacy as a four-dimensional configuration of value alignment, action feasibility, relational robustness, and consequence bearability. The framework bridges factual judgment, value evaluation, and complex systems analysis, offering a normative foundation for rational decision-making in open systems.