When Only Proof Remains: A Modal-Semantic Challenge to Atheism

This paper develops a novel modal-semantic ontological argument that challenges the semantic coherence of atheistic discourse itself. By introducing the Reasonability Principle (RP), it is argued that any truth — including atheism — must be supported by at least one analytic or synthetic reason. However, synthetic arguments against God’s existence, such as those based on evil, divine hiddenness, or explanatory parsimony, rely on semantic structures that presuppose the metaphysical possibility of a being whose existence they deny. If the concept of God functions as a rigid designator referring to a necessarily existing being, then — under modal logic S5 — mere possibility entails necessity. Thus, atheistic conditionals implicitly commit to God's necessary existence. The paper concludes that atheism entails a semantic self-undermining, unless it can provide a purely analytic proof of God’s incoherence — a standard not met by existing arguments. Hence, theism emerges as the semantic price of atheism’s intelligibility.