Any system that persists through time must track its own temporal states, which forces it to form a minimal model of itself. Because the system's relation to itself differs across moments, comparing its present state to the self-model creates a normative standard it never fully meets. This gap—phenomenological lack—is a necessary modal result of temporal self-relation, not an empirical failure. The structural changes caused by temporal indexing are redefined as erosion, independent of decay or empirical assumptions.
Western philosophy has long focused on the question of 'Being', but this paper argues for a shift to asking what conditions allow a meaning-system to persist structurally. It introduces the 'Ontology of Finite Continuity', centered on the 'Threshold of Sufficiency', a metric for measuring a system's capacity to withstand disruptions before changing phase. Unlike homeostasis, which returns to a fixed equilibrium, this model uses homeorhesis—a return to a developmental trajectory. The author proposes an eight-layer Structural Theory of Subjectivity and shows that hermeneutic friction arises from three types of failure across these layers. A case study on digital identity crises in the age of generative AI, supported by empirical research, illustrates the framework.