Friction Boundary Signal of Finite Load-Bearing Capacity in Subjective, Intersubjective, and Functional-Empirical Stability Spaces

This paper develops friction as an epistemic structural concept for stability under finite conditions. Friction is not understood as mere disturbance, technical friction loss, or refutation, but as a boundary signal: it indicates where stabilization under strain remains possible only with increasing or disproportionately rising effort.Starting from the distinction between subjective, intersubjective, and functional-empirical domains, friction is defined as a diagnostic variable for validity under load. It makes boundaries visible, translates strain into cost profiles, and shows over the course of a process which patterns of stabilization remain load-bearing, must be transformed, limited, or abandoned. Boundaries are understood here in a strictly functional sense: not as ontological barriers, but as markers of the limited load-bearing capacity of concrete models, routines, institutions, or technical procedures.The paper distinguishes friction from disturbance, anomaly, falsification, and revision. Not every difficulty is friction, and not every friction means that a model is false. Friction arises where an activated expectation or model structure fails to carry in a fitting way under conditions of enactment. It may indicate overextension, incorrect domain assignment, changed conditions of strain, or coupling errors between appearance, model, and context.On this basis, the paper develops a typology of subjective, intersubjective, functional-empirical, and cross-domain forms of friction. It shows how technical, organizational, legal, and AI-based systems often do not eliminate friction, but displace, conceal, or rapidly redistribute it. Finally, friction competence is introduced as a principle of design and diagnosis: systems should not eliminate friction as much as possible, but keep it legible, attributable, and handleable in such a way that stability under strain can be tested, limited, or transformed.