The Cost of Dual Persistence: Radicalised Constraints and the Price of ExistenceThis paper presents a unifying conceptual framework for understanding persistent failure, harm, and escalation across biological, cognitive, social, and technological systems. Rather than attributing such outcomes to error, malign intent, or external disruption, the work proposes that many real-world pathologies arise from radicalised constraints—local enforcement mechanisms that continue operating beyond their legitimate scope after losing recall and reintegration authority. The analysis is grounded in a persistence-first ontology, where outcomes are not chosen but emerge because configurations that continue necessarily outlast those that do not. Within this view, duality—the capacity for systems to act locally while persisting globally—requires reversible participation across scales. Harm arises when constraints cross this bridge of duality and fail to return, often through the acquisition of self-reinforcing "hot" mechanisms that bypass cooling, checkpoints, or stand-down conditions. Using brief structural illustrations from biology (including cancer, immune responses, viral mechanisms, and DNA repair), the paper demonstrates how functionally correct processes can become misplaced without malfunction or intent. It further identifies a hidden evolutionary pressure intrinsic to dual systems: the continual exploration and capture of opportunity wherever persistence permits, producing both adaptation and pathology as equally valid expressions of continuation. The work reframes intervention away from suppression and toward governance, recall, scope, and reintegration, arguing that radicalised constraints are not anomalies but the unavoidable price of dual existence. This framework is intended as a conceptual keystone, clarifying recurring patterns across domains and explaining why many force-based solutions systematically fail.