Some commentators have worried that Descartes‘s ontological proof is a kind ofafterthought, redundancy, or even embarrassment. Descartes has everythingneeded to establish God as the ground of certainty by Meditation Three, so whybother with yet another proof in Meditation Five? Some have even gone so far asto doubt his sincerity.1Past literature on this topic is of daunting variety andmagnitude, dating back to the seventeenth century.2The current discussion hasfocused on Descartes‘s premises in relation to the coherence of his concept ofGod.3I wish to (...) take up this issue from a somewhat different tack, showing that Descartes‘s ontological proof actually involves a subtle change in the direction ofhis argument from a reflective to a recollective theory of innateness. In the FifthMeditation, Descartes does not simply expand on his previous discussion of God,which arose out of reflection on his self; rather, the ontological proof depends ona kind of recollection of God‘s being that could only be based on the causalpositivity, or ―power,‖ of His existence. God is the structural cause of our idea ofhim and thereby restricts the way in which we may think of Him, in the sameway as the essence of a triangle structurally determines the ways we must thinkof it.4We are not free to construct such ideas in any way we want, so there mustbe a cause, or a reason, that restricts such construction.The specific argument of Meditation Five, however, must be understoodin its larger context, for part of the structurally determined idea of God containsnecessary existence, which Descartes interprets in terms of causal power. In theprocess of explaining this causal power, first to Caterus and, later to Arnauld,Descartes develops a way of interpreting God‘s causal relationship to himself, interms of a scholastic distinction between God as causa sui and ens a se, whichpreserves the universality of the causal principle and allows us to understand whyGod can be considered as the formal cause of His own being—the self-groundingground of all existence—an idea of subsequent importance to Malebranche andSpinoza, among others. Understanding this position on God and cause allows usto see a complementarity between Mediations III and V that has previously beenoverlooked.5While the principle of eminent causality found in Meditation Threeis central to the structural causation argument of Meditation Five, it is God‘spower, the positivity of His causal relationship to himself, that allows theargument from his effects to his existence in the first place.The dualistic structure to Descartes‘s arguments for God‘s existence inMeditations Three and Five mirrors Anselm‘s approach in the Monologion andthe Proslogion. Appreciating this stylistic debt is crucial for understandingDescartes‘s attempts to improve on Anselm‘s arguments, as well as his attempt totruly ground all knowledge in the certainty of God‘s existence. Yet whileAnselm‘s dual argument is ultimately based on a negative intuition of God‘sbeing, described in the Monologion as that without which the world cannot be,Descartes‘s dual argument in Meditations Three and Five is based on a positiveintuition or recollection of God‘s being as a necessary structural restriction on our concepts of the world. The ontological proof is primarily based on thisrecollective theory of innateness. It is God as causa sui, recollected as thenecessary ground of all things, that is the sole efficient cause of the existence ofevery finite, limited thing—especially human beings and their clear and distinctideas. (shrink)