AN AXIOMATIC FORMULATION OF ONTOLOGICAL TAWHI ̄D: . Divine Oneness, Non-Duality, and the Phenomenal World: A Comparative and Critical Study

Problem. Tawhıd — the Islamic affirmation of divine oneness — has been extensively treated in theological and ritual registers, but its structure as an ontological postulate remains under-formalised. In particular, no existing account supplies a non-circular proof of singular existence, a rigorous treatment of how phenomenal multiplicity is consistent with ontological unity, or a precise positioning of Islamic non-dualism within contemporary analytic metaphysics. Approach. We present an axiomatic formulation of Ontological Tawh ̄ıd . grounded in three axioms — no existence besides E; every appearance is ontologically identical with E; phenomenal differentiation is a cognitive construct — situated within the modal system S5 under a conditional necessity reading that preserves phenomenological modesty. The methodology combines formal proof, ontosemantic analysis of Qur’anic pronominal shifts, cross-tradition comparison, and engagement with analytic metaphysics. Results. The main formal contribution is a non-circular proof of singular existence, replacing the circular use of the identity axiom with an independently motivated principle (OD) — reconstructed using Fine’s grounding operator as (OD∗) — grounded in a restricted Principle of Sufficient Reason and an anti-regress argument. The framework is identified as Exclusive Monism, distinguished from Schaffer’s Priority Monism and Mereological Nihilism, and shown to generate detectably different verdicts on the combination problem, mathematical Platonism, and the problem of evil. An explicit acknowledgement of the is–ought gap in the ethical derivation is provided. Significance. The framework contributes to Islamic metaphysics, comparative theology (Advaita Veda ̄nta, Wahdat al-Wuju ̄d), and analytic metaphysics simultaneously, offering a shared formal vocabulary for non-dual positions across traditions while identifying the precise points at which they diverge.