Descartes' philosophy concerning the relationship between God and the eternal truths has been an unresolved and problematic issue since he first declared it. For Descartes, God's power is limitless and nothing can exist independently of Him. The problem is that if that is true, things such as "God knows that he does not exist" are possible because the truth of that proposition rests on God's power. In fact, the existence of any eternal truth depends on God’s power. Examples of such truths are: "the interior angles of a triangle are equal to two right angles," "3+4=7," and "two contraries cannot exist together." Descartes built his entire metaphysics around a certain conception of God, a conception that includes His not being a deceiver. But if it turns out that God is as limitless as Descartes thinks He is, Descartes' philosophy does not rest on as firm a foundation as he believes. In fact, it is inconsistent: we know what we clearly and distinctly perceive because God would not deceive us and his power is unlimited. But since His power is absolutely unlimited, it might be the case that God is not a deceiver and everything we know is true, but at the same time we have been misled by God and there is an actual reality we are not, and will never be, privy to. There have been a number of attempts to make Descartes’ view consistent. I consider two of the most recent and promising lines of interpretation. The first, Universal Possibilism, holds that God’s power is utterly limitless and He can make any proposition true, including problematic ones such as “I think, but I am not.” This theory argues that what we can and cannot conceive are merely epistemic limits rather than indicators of truth. The second, Limited Possibilism, maintains that God has power over the possibility of any proposition. Any proposition, under this view, is possibly possible; this preserves the integrity of the connection between what we conceive as true and what is actually true. The major drawback to this line of thought is that it puts an unintuitive limit on God: He can make something possible, but he can’t then do the seemingly simple task of making that thing true. I argue that a proper understanding of Descartes' conception of the meanings of "possible," "impossible," "contingent,". "necessary" and God's nature renders his position consistent. Descartes holds that God necessarily exists, and his nature is immutable and the existence of anything else is contingent. If one interprets Descartes' God to hold limitless power over contingent propositions, but not over his nature or existence, Descartes' position is no longer inconsistent.

Much ado has been made regarding Descartes's understanding of the creation of what he called the "eternal truths" because he described them, paradoxically, as both the free creations of God, and necessary. While there are many varying interpretations of Cartesian modality, the issue has heretofore been treated in a vacuum, as a niche issue having little import beyond being an interesting puzzle for Descartes Scholars. I argue that this treatment is misguided, and that in order to properly understand Cartesian philosophy at all, one must properly understand Descartes's theory of modality. This, however, is no small feat; in order to understand Descartes's seemingly peculiar view on modality, one must first make sense of what Descartes understood the nature of God to be. One reason for this, I argue, is the systematic nature of Cartesian philosophy; indeed when dealing with a dense inter-connection of philosophical issues, one must move from what is more known in itself to what is more known to us, and not the other way around. I argue that in the literature on Cartesian modality, insufficient attention has been paid to the influence of the French School of Spirituality (in particular the work of Cardinal Bérulle) on the Cartesian notion of the divine. I argue that this influence pushed Descartes to criticize traditional attempts (Aquinas's in particular) to split the horns of Plato's Euthyphro dilemma as violating a proper understanding of the doctrine of divine simplicity. Descartes's commitment to a radical form of the doctrine of divine simplicity leads him to a version of divine voluntarism wherein all `things' depend on God for their existence, and God cannot have had antecedent reason to prefer the creation of anything over anything else. There is little doubt that Descartes embraced the voluntarist horn of the Euthyphro dilemma, but just what that means for Cartesian modality and philosophy generally remains a contentious issue. I argue that Descartes is best read as what I call an `agnostic quietist' regarding God (and modality generally) given textual, historical, and systematic considerations. One virtue of an agnostic quietist reading is that I am able to square the passages where Descartes discusses the inconceivability of God's power with the conclusions reached regarding God's non-deceiving nature in the Meditations and elsewhere. Further virtues that I explore are the effects that a quietist reading has on the Cartesian scientific programme, the infamous mind-body problem, Descartes's seemingly inconsistent view regarding human free-will and Descartes's refusal to engage in "theology." Traditionally, Cartesian epistemology has been understood to be a purely a priori undertaking, which succumbs to deep and insurmountable problems. One of the greatest problems facing the Cartesian was the move from the mind to the world. Simon Blackburn, for example, says of the Cartesian epistemological project in the Meditations that Descartes "has put himself on a desert island from which there is no escape." This view is echoed by, and even motivates some of the contemporary views concerning Cartesian modality. I argue, however, that a proper understanding of the Cartesian doctrine of clear and distinct ideas circumvents this famous problem. By highlighting the proper understanding and application of the doctrine of clear and distinct ideas, I show that such ideas not only guarantee the existence of an external truth-maker, but also that such ideas do not do much more than show that there is a truth-maker. I argue that in instances of clear and distinct perception, the truth of the idea is normatively certain, but what makes it true is yet to be established. In this way, clear and distinct ideas are both powerful, in terms of guaranteeing truth, and relatively unhelpful, in that further work is required in order to determine to what the ideas conform. I argue that this is the case not only for actual truths, but for some clearly intuited truths about possibility. As an illustration of my overall thesis, I address the Cartesian argument for the separability of mind and body, and entertain the various interpretations of Descartes's view of human freedom. I argue that in order to understand Cartesian views on either of these issues, one must first make sense of his modal commitments. In both of these cases Descartes claims that finite minds can know that something is possible, even though what makes it possible is well beyond what they can understand.