Existential Vulnerability and the Structure of Subjectivity: A Defense and Empirical Specification of the Dual-Closure Framework

Contemporary philosophy of mind faces a methodological crisis: functionalist theories explain cognitive capacities while leaving the hard problem untouched, and physicalist accounts cannot distinguish genuine consciousness from sophisticated mimicry. This paper argues that the Dual-Closure framework—which grounds authentic feeling in non-duplicable existential vulnerability—not only withstands major objections from functionalism, physicalism, and psychological continuity theory but generates unique empirical predictions that competing theories cannot match. Through systematic engagement with Parfit's fission cases, Dennett's functionalism, neuroscientific counterexamples, and constructivist ethics, I demonstrate that objections to the framework reveal the inadequacies of alternative accounts rather than undermining Dual-Closure claims. The framework stakes its validity on five testable empirical conditions—including consciousness survival through cryonic revival, upload discontinuity, and copy-indifference resistance—thereby meeting scientific falsifiability standards while preserving philosophical rigor. I introduce "denial trajectory analysis" as a diagnostic method for evaluating metaphysical frameworks and show that the escalating implausibility required to deny Dual-Closure constitutes independent evidence for its validity. The framework successfully explains phenomena across multiple domains—the hard problem, personal identity, animal consciousness, normative grounding, and AI ethics—within a unified account that competing theories cannot match.