God’s Possibility and the Compossibility of Ideas. How Leibniz Tries to Lay the Foundations for Descartes’ Ontological Proof (Part II)

Abstract

Leibniz tries to prove God’s possibility on the basis of absolutely positive and simple perfections. I primarily want to show, how these controversial perfections can be made comprehensible by working out their foundations in Plato’s theory of ideas. After having concentrated on the Cartesian proof and Leibniz’s criticism in the first part of my paper, I now focus on his own version of the proof and its Platonic background. First, I discuss the structure, the advantages and disadvantages of the famous argument in “Quod ens perfectissimum existit” [1676]. Then I investigate his reasons for assuming absolutely positive and simple perfections by tracing them back to Platonic ideas, including the paradigmatic role of the kosmos noȇtos for the compossibility of essences in the regio idearum . I also consider in which sense Plato’s theory of ideas already preforms the structure of ontological proofs, and how it tells against the assumption of a strictly univocal meaning of existence.