Reassembling Identity: A Multi‑Tier Framework for the Ship of Theseus in Contemporary Bio‑, Zoo‑, Tech‑, and Digital Ethics

Reassembling Identity: A Multi‑Tier Framework for the Ship of Theseus in Contemporary Bio‑, Zoo‑, Tech‑, and Digital EthicsAuthor: Khan Tahsin AbrarAffiliation: Independent Researcher, BangladeshEmail: khan.tahsin.abrar.kta@gmail.com ORC-iD: https://orcid.org/0009-0009-4631-6768 AbstractThe Ship of Theseus paradox interrogates whether an object that undergoes piecemeal replacement remains "the same." Twenty‑first‑century debates now span organ transplantation, adoption law, companion‑animal status, blockchain‑asset upgrading, artificial intelligence persistence, and virtual avatar identity, yet few accounts differentiate among the ontological strata involved. This conceptual paper proposes a comprehensive four‑tier taxonomy: living conscious superiors (LCS), living conscious mid‑ to low‑level beings (LCML), inanimate objects (IO), and digital entities (DE), and advances an Enhanced Informational‑Functional Continuity (IFC) criterion that reframes identity as persistence of informational state and social function rather than strict material sameness. Classical philosophy, immunology, developmental psychology, animal‑law precedents, blockchain technology, and artificial intelligence research are triangulated to test IFC across seven pressure‑test cases: solid‑organ transplantation, legal adoption, household‑pet rehoming, vintage‑asset refurbishment, digital asset evolution, AI memory persistence, and avatar identity formation. Analysis shows that (a) LCS identities are narratively thick and non‑transferable; (b) LCML identities are behaviorally contingent and partially transferable; (c) IO identities are owner‑indexed and broadly transferable. IFC accommodates these gradients while dissolving reductive mereological debates and addressing emerging technological challenges in digital identity management. Implications include tighter consent regimes in regenerative medicine, ethically justified restrictions on child commodification, nuanced legal recognition of companion animals as "quasi‑kin," blockchain‑based identity verification protocols, and frameworks for AI rights and avatar embodiment. The paper closes by outlining empirical and normative research agendas for policymakers, technologists, philosophers, and digital rights advocates.