Natural Theology and the Concept of Perfection in Descartes, Spinoza and Leibniz

One of the hallmarks of the early modern rationalists was their confidence that a great deal of metaphysics could be done by purely a priori reasoning. They thought so at least partly because they inherited via Descartes Anselm's confidence that the existence of God could be established by purely a priori reasoning in an ontological argument. They also inherited a Thomistic and scholastic confidence that the concept of God as supremely perfect being, if subjected to serious and deep analysis, would yield sound doctrine. Descartes, Spinoza, and Leibniz all three took it that they had in their stock of ideas an idea of God sufficiently clear and detailed that a little analytic work could produce real metaphysical results, not only about God himself, but also about the universe in which they found themselves (for Spinoza, these turned out to be the same thing). Though they start with what purport to be ideas of the same God, they get radically different results in their analyses.