Abstract

According to leibniz, Descartes' ontological argument establishes that if God possibly exists then God exists. To complete the argument a proof that God possibly exists is required. Leibniz attempts a proof-Theoretic demonstration that 'god exists' is consistent and concludes from this that 'god possibly exists is true'. In this paper I formalize leibniz's argument in a system of modal logic. I show that a principle which leibniz implicitly uses, 'if a is consistent then a is possibly true' is either mistaken or useless in completing the ontological argument