The Relational Necessity of Determinacy: Why Determinate Being Cannot Be Grounded Non-Relationally

This paper develops a structural argument that determinacy — the fact that anything that exists is this rather than that — cannot be grounded in any non‑relational primitive. The logical space of non‑relational individuation is exhaustively mapped into two strategies: locating the individuating principle within the term (haecceities, bare substrata, primitive thisness) or outside it without genuine connection (positional or descriptive accounts). Every path through this space collapses into one of three structural failure modes: empty labelling, covert reinstatement of relation, or the dissolution of determinacy. The core result is the boundary argument: any articulated individuating feature draws a boundary, and a boundary is constitutively contrastive — an irreducibly relational structure. A prior actuality problem shows that non‑relational primitives cannot secure their own reality without regress or brute stipulation. The conclusion is transcendental: determinacy requires constitutive contrastive structure, and no non‑relational alternative can meet the conditions of individuation. The paper closes the non‑relational space and clarifies what any adequate relational account must explain.