Anyone who has encountered Anselm’s ontological argument for God’s existence probably felt like he was wrestling with a chimera or staring at an image that’s always changing. From Anselm’s contemporary Gaunilo to Thomas Aquinas to David Hume and Immanuel Kant, philosophers through the ages have disputed the internal logic of Anselm’s claim that God’s existence logically follows merely from the definition of God. Thomas’s critiques are some of the more famous and devastating, given that he and Anselm share the same basic premises about the nature of perfection and the nature of God (not so for some of Anselm’s more modern detractors). But what may perhaps be surprising to many readers is that the strongest defense of Anselm in the face of Thomas’s critique comes not from a medieval, but from René Descartes: the very philosopher many people call the father of modernity. While many people blame Descartes for the loss of medieval scholasticism and the beginning of all the ills of modern thought—whether rightly or wrongly we do not have the space to adjudicate here—an examination of his Meditations on First Philosophy will show that he was one of history’s staunchest defenders of Anselm’s argument—while not mentioning Anselm by name—and he did so through the use of Thomas’s own arguments for the existence of God and the traditional scholastic categories of objective and formal existence.
Anselm’s Ontological Argument
In his Proslogion Anselm famously attempts to understand by reason what he grasps by faith—namely the nature of God. In his opening prayer, he says, “I do not seek to understand so that I may believe, but I believe so that I may understand.”[1] He then sets out to understand that God exists and that he is what Christians believe him to be, arguing that the knowledge of the latter logically entails the former.[2] God can be defined as “that than which nothing greater can be thought.”[3] Of course, Anselm recognizes that to be able to conceive of something doesn’t necessarily entail its existence, for the artist can conceive of a painting and never bring it into existence. Yet it cannot be denied that even the fool who says in his heart “there is no God” can understand the concept of God as “that than which no greater can be thought,” and thus have the true concept of God in his understanding. From here, all Anselm needs to prove is that to have God in the understanding as “that than which nothing greater can be conceived” does necessitate his actual existence, unlike the painter and his painting. He does this by reference to the definition itself, for if this thought exists only in the understanding, “it is possible to think of it existing also in reality, and that is greater.”[4] Since existence in reality is greater than mere existence in the understanding, “that than which nothing greater can be conceived” must exist in reality for it to be greater than any other thing that can be thought.[5] Further, it is impossible to think of God as not existing insofar as someone truly understands that which God is, for God “is of such a kind of existence that he cannot be thought not to exist.”[6] Anselm’s argument is elegant, for he starts with a definition of the mind—what can be conceived—and by this starting point, argues that the mind’s ability to conceive provides a foundation of proof for God’s actual existence. Or, to put it another way: to understand who God is entails that he most certainly exists.
Anyone who has wrestled with Anselm’s proof must affirm that he had a dizzying intellect. Often, I find this proof to be like those ambiguous images that look one way and then suddenly look like something else, alternating between two perspectives that render each unstable and hard to keep fixed in one’s sight. On certain days, the proof seems unassailable, while on other days, it seems incredibly flimsy and almost impossible to grasp, depending merely on word games. Many theologians have tried to dismantle Anselm’s argument, while others vehemently defend its logical soundness, even if it doesn’t always seem persuasive. One of the most famous critiques of Anselm’s argument is by Thomas in Summa Theologica Part 1, Question 2, Article 1.
Thomas’s Critique of Anselm’s Ontological Argument
Thomas asks whether God’s existence is self-evident, articulating Anselm’s position in Objection 2 before rejecting it. First, Thomas argues that while the proposition God exists is self-evident in itself—for the predicate “is” is the same as the subject “God” since God is “self-subsistent being”—it is not self-evident to us because we do not know the essence of God, and thus we require things better known to us—God’s effects—to aid us in our knowledge of God.[7] Second, Thomas argues that man’s innate knowledge of God is only knowledge of God in “a general and confused way”—such as God being man’s true happiness, which all men desire, although man may not define happiness as God and thus not know him clearly and distinctly.[8] Having established this, Thomas then argues that Anselm’s argument fails, for even if everyone understood that God signifies “that than which nothing greater can be thought,” it doesn’t follow that “what the name signifies exists actually, but only that it exists mentally.”[9] In other words, the gap between “actual existence” (formal existence) and “mental existence” (objective existence/thought) is too great. To be able to conceive of something (even God) does not necessitate that it actually exists, but merely that it exists in the mind. Thus, in order for the ontological proof to work—according to Aquinas—it must be shown that the very ability to conceive of God necessitates his actual existence, thus bridging the gap between thought and “actual existence.” Anselm, Thomas claims, is unable to bridge this gap merely through the definition of God, for the definition itself is only grasped in terms of its “existing mentally” unless it has already been proven that “that than which no greater thing can be thought” exists actually, which would be circular, being the very thing he set out to prove. Thus, in order to bridge this gap between thought and actual existence, it is required to investigate the cause of thought. Or to put it another way, the actual existence of God must be shown to be the source of one’s understanding of God as “that than which nothing greater can be conceived.” Enter René Descartes to bridge the gap.
Descartes’ Geometric Scaffolding
In his famous Meditations on First Philosophy, René Descartes sets out to prove the existence of God and the soul by demonstrable reasoning that “has no other source but [the] mind.”[10] He does not do this because he thinks faith and Scripture are insufficient for belief in God, however. In his prefatory letter to the faculty of the Sorbonne, Descartes affirms that for believers, it is enough to believe in God by the gift of faith and that the primary foundation for belief in God is Holy Scripture; in this sense, he is right in line with Anselm.[11] Nevertheless, he maintains that such arguments will not persuade the unbeliever because it will be deemed to be circular—Holy Scripture having its authority by the inspiration of the God it attests to be true.[12]
“Anyone who has wrestled with Anselm’s proof must affirm that he had a dizzying intellect.”
The first major step in Descartes’ proof lies in his methodological doubt. In order to establish the most epistemologically certain foundation for his proof, Descartes begins by tearing down everything that can be doubted. Whatever remains can be used as the starting point, for it must be self-evident, non-contradictory, and impossible to call into question. If—as Descartes claims—God and the soul are “the most certain and evident of all possible objects of knowledge for the human intellect,” then it follows that knowledge of these things rests on the most certain and evident premises.[13] To find these certain and evident premises, Descartes doubts everything that can be doubted. By doing this, he creates something akin to the common notions, definitions, and postulates in geometry—foundational ideas from which he can build all knowledge.
While his senses tell him that he is by the fire and his hands are out in front of him, he notes that his senses could be deceiving him, or he might be insane or dreaming.[14] Simply having an experience doesn’t guarantee that what one is sensing is objectively real. Nevertheless, the objects that one’s mind sees—even those in dreams—seem to be drawn from things outside of the self, which can be reduced to several classes of things: corporeal nature, extension, shape, quantity (size and number), place, and time—the things that are the most simple and general from which all composite things derive.[15] The question, then, is two-fold: 1) can the mind be trusted to know anything about these classes (such as the sum of two and three)? and 2) from whence could our knowledge of these things come (either from knowledge of self or knowledge of something outside the self)? This second question is the hinge on which Descartes’ ontological proof turns.
While it may be the case that one can trust one’s mind to have objective knowledge of these things, one cannot be certain that the mind isn’t deceived. If there is no God and all is ordered by chance, then the person may be “so imperfect as to be deceived all the time,” or at least has no certainty that he is not deceived about even the most fundamental things.[16] But supposing that there is a God, one could posit that the God is a “malicious demon” that has deceived the mind and “ensnared” the judgment so that the senses cannot be trusted.[17] In either case, one can suppose that all opinions gained from sensory experience could be false or imaginary.[18]
“Simply having an experience doesn’t guarantee that what one is sensing is objectively real.”
It must be noted that many people have misinterpreted Descartes’ claims and aims on this point. Descartes does not attempt to prove that knowledge from sense experience is false or imaginary, nor does he show that it is even reasonable to reject empirical knowledge; rather, he notes that knowledge derived from the senses produces “highly probable opinions” that he must assume are false to ensure that he doesn’t unwittingly fall into holding premises that are attained through “habitual opinion” rather than clear and evident proof.[19] Descartes recognizes that in the temporal order of knowledge, everyone comes to their most certain conclusions by means of the senses.[20] He even goes so far as to say that if the only cause to doubt empirical knowledge is the reality of a deceiving God, then this reason for doubt “is very slight.”[21] In this sense, Descartes does not reject empirical knowledge as a means of knowing, nor does he claim that empirical knowledge is by its own nature noetically suspect. Rather, he asserts that through empirical knowledge, one cannot know for certain that he is not deceived.[22] If this is the case, then knowledge not contingent on the senses is required to justify one’s trust in empirical knowledge, and this form of knowing would then be considered more certain and more foundational, even if it is not the ordinary means one uses to come to the knowledge of the truth.[23] Furthermore, he clearly states that the benefit of his method isn’t that it proves the existence of external reality, for “no sane person has ever seriously doubted these things.”[24] Rather, he seeks to show that knowledge of God and the self is even more certain than knowledge of external reality.[25] In this way, Descartes argues for the priority of the mind both as a means of certain knowledge and also as what is most central to the essence of a human being.[26]
“In order to establish the most epistemologically certain foundation for his proof, Descartes begins by tearing down everything that can be doubted.”
Having assumed his methodological doubt, he sets out to find anything “certain and unshakeable” on which he can build his proof.[27] In brief succession, he proves he exists,[28] that he is “a thinking thing,”[29] and that his knowledge of his own mind is greater than the knowledge derived from his senses, for it is the mental act of “judging” and “the scrutiny of the mind” that is more “clear and distinct” than the external knowledge of objects derived from the senses.[30] If this be the case, then even if what we experience with our senses is not real, our knowledge of how the mind functions and acts toward that stimuli is certain; thus, our knowledge of the mind is more certain than the knowledge of external physical phenomena.[31] Therefore, to determine whether anything exists outside of the mind, we must consider the mind itself, specifically how it arrives at certain thoughts and whether any of these thoughts can be said to be produced from something outside the mind.
Regardless of whether one is persuaded by Descartes’ argument for the knowledge of the mind being more clear and distinct than empirical knowledge, his following argument from causation has the greatest bearing on Thomas’s critique of Anselm, for here he explores the causes for one’s innate ideas, seeking to disprove Thomas’s claims that God isn’t known clearly and distinctly, that the idea of God isn’t innate, and that the ontological proof is logically invalid. He does this with the aid of two of Thomas’s proofs for God’s existence: namely, the arguments from efficient cause (proof 2) and from perfection (proof 4).[32]
Descartes’ Answer to Thomas
At this point in the proof, Descartes has established several premises: 1) he exists as a thinking thing; 2) knowledge acquired by means of the mind alone is more certain than knowledge contingent on sense perception; 3) knowledge of the mind itself is clearer and more certain than knowledge of external phenomena; and 4) “Whatever [one] perceive[s] very clearly and distinctly is true.”[33] From here, Descartes swiftly moves to his conclusion that God exists by means of a proof that shares features of Anselm’s “ontological argument” and Thomas’s various arguments from causation.
In order to prove from these premises that God exists, Descartes begins by delineating three categories of ideas: 1) innate ideas; 2) adventitious ideas—ideas that seem to come from outside the self; and 3) invented ideas.[34] Insofar as ideas exist solely within the mind and do not refer to things outside of the self, then they cannot be considered false. But the activity of judgment seeks to determine whether “the ideas which are in me resemble, or conform to, things located outside me.”[35] Invented ideas are sourced within the creative powers of the mind and cannot be judged to resemble things located outside the self. Adventitious ideas seem to come from outside the self and are known empirically but—so far in the chain of reasoning—cannot be proven to correspond to reality.[36] By this, Descartes means that while we have a base intuition that our adventitious ideas correspond to external reality, this cannot be proven by a faculty as clear and certain as “the natural light,” by which he means his power of reason according to self-evident laws of logic, such as the law of identity or non-contradiction or the excluded middle, or the power of reason operating purely on things that are beyond doubt.[37] Adventitious ideas are not “clear and distinct” like those we come to know through the natural light. And even if our adventitious ideas did originate from something external to the self, it does not follow that we can be certain our ideas rightly correspond to the object itself.[38] Hence, to be certain that God exists, Descartes must also prove that the idea of God is innate and thus can be known clearly and distinctly by the natural light of reason alone.
“We must consider the mind itself, specifically how it arrives at certain thoughts and whether any of these thoughts can be said to be produced from something outside the mind.”
Before proving the innate idea of God, Descartes proves the existence of God through an argument from causation, the structure of which is similar to Thomas’s argument for God through efficient cause, even though the focus of the arguments is different. In short, there must be an efficient cause for every idea within the mind. To establish this, he appeals to the scholastic distinction between objective and formal reality. Objective reality refers to the mental impression or idea caused by an object. Formal reality refers to the actual object that causes the idea. Every idea contains an “objective reality” that corresponds to the formal reality of the thing itself so that whatever “greatness” or reality is within the formal reality of the object, that greatness or reality exists “objectively” within the mind to some extent.[39] With these categories, Descartes establishes important rules of causation: 1) “there must be at least as much reality in the efficient and total cause as in the effect of that cause”[40]; 2) something cannot arise from nothing; 3) what is “more perfect” or “contains more reality” cannot come from something less perfect or with less reality.[41] This leads to the important conclusion: “In order for a given idea to contain such and such objective reality, it must surely derive it from some cause which contains at least as much formal reality as there is objective reality in the idea,” otherwise the idea contains something that emerged from nothing, which is impossible.[42]
It is not enough to reply that objective ideas can arise from other ideas, for “eventually one must reach a primary idea, the cause of which will be like an archetype which contains formally and in fact all the reality or perfection which is present objectively or representationally in the idea,” lest there be an infinite regress.[43] This cause must have formal reality, for “the formal mode of being belongs to the causes of ideas [. . .] by their very nature.”[44] Hence, the foundational cause for any objective idea must be a formal reality that is equal to or greater in perfection than the idea, whether that formal reality is the mind itself or something external to it.[45] Since this is self-evidently true, Descartes can establish another key premise: “If the objective reality of any of my ideas turns out to be so great that I am sure the same reality does not reside in me, either formally or immanently, and hence that I myself cannot be its cause, it will necessarily follow that I am not alone in the world, but that some other thing which is the cause of this idea also exists.”[46]
From here, it logically follows that there must be a formal cause outside of the self that accounts for the idea of God. Descartes’ argument seems to make use of an argument from perfection, similar in structure to Thomas’s argument from perfection while differing in focus and application. While other ideas might possibly be construed to originate from the self, the idea of God certainly cannot formally exist within the self because God is more perfect than the self.[47] At this point, he offers a definition of God consistent with traditional understanding, but distinct from Anselm’s–, not because he rejects Anselm’s definition (he uses it in “Meditation Five”), but because he must first answer Thomas’s critique about the necessity of God’s existence before offering Anselm’s formulation to fully bridge the gap. God is defined as “a substance that is infinite, independent, supremely intelligent, supremely powerful, and which created [all things].”[48] He goes on to describe this being as absolutely perfect in every way. This idea of God is far greater and more perfect than any human being, so it is impossible for these ideas to formally originate in the human mind. Hence, the formal cause of this idea of God must be outside the self and in a being at least as preeminent as the idea.[49] Because the self is finite and imperfect, it cannot be the formal cause of the idea of an infinite and perfect deity. In fact, one’s knowledge of one’s own finitude and imperfection speaks to the priority of God’s perfection and infinity, thus making it impossible for the human mind to be the formal cause of the idea.[50]
“…there must be an efficient cause for every idea within the mind.”
From here, Descartes quickly goes through other possible causes of the idea and shows their falsity. The idea of God cannot come through negation or a knowledge of a lack in the self—such as the idea of cold—for infinitude and perfection are by definition more real than the self.[51] While the idea of God cannot be fully grasped—because it is higher than the self—it can still be understood clearly and distinctly in so far as it can be known, which is enough to know that its formal cause must reside outside the self.[52] The self also cannot be the formal cause, because even if it were far greater than it knew itself to be, it possesses potency, change, and cannot cause itself, while God is pure actuality, does not change, and is the cause of all being.[53] There must be an ultimate cause outside the self that is self-existent, and thus God. Lastly, this idea cannot be formally caused by the mind bringing together a composite of many things outside the self to form an idea of a perfect being, for part of the perfection of God is his unity and simplicity—something that nothing else possesses.[54] Hence, God isn’t known adventitiously, through the senses, or through abstraction from knowledge of the self.
If this be the case, then the idea of God could not originate from the mind’s invention nor from an adventitious cause. Hence, it must be an innate idea just like the knowledge of the self, known clearly and distinctly by the natural light.[55] Therefore, he concludes: “I recognize that it would be impossible for me to exist with the kind of nature I have—that is, having within me the idea of God—were it not the case that God really existed—a God, I say, the idea of whom is in me, who possesses all those high perfections which, however they may transcend my powers of comprehension, I am yet in some fashion able to reach in thought.”[56]
Through this proof, Descartes answers Thomas’s main critique of Anselm, showing how the idea of God is innate, is clear and distinct, and necessitates the real formal existence of God outside the mind, and he makes use of scholastic logic and the structure of Thomas’s own arguments for God’s existence.
Having established this, Descartes offers Anselm’s ontological argument in “Meditation Five,” arguing that God’s essence necessitates his existence actually, for “a being completely perfect” cannot lack any perfection, and not existing is certainly lacking a perfection.[57] Whereas in other things one can conceive of essence without believing it exists actually, existence is as inseparable from God as a valley is inseparable from a mountain or as the equality of a triangle’s three angles being equal to two right angles is from the nature of a triangle as a three-sided polygon.[58]
One might object that even though I cannot conceive of a mountain without a valley, this doesn’t entail that a mountain or valley actually exists; in the same way, merely thinking that God exists doesn’t entail his actual existence. But Descartes responds by showing that for God, existence is to essence as valley is to mountain, such that one cannot think of God as not existing, just as one cannot think of a mountain without a valley: “In the case of God…I cannot think Him save as existing; and it therefore follows that existence is inseparable from Him, and that He therefore really exists. It is not that this necessity is brought about by my thought…on the contrary, the necessity which lies in the thing itself, that is the necessity of God’s existence, determines me to think in this way.”[59] It is impossible for the mind to conceive of God save as existing. In this, his argument is identical to Anselm’s.
“This idea of God is far greater and more perfect than any human being, so it is impossible for these ideas to formally originate in the human mind.”
Thomas argues, however, that many people do not think of God at all; and when they do, they do not necessarily define or think of him in this way. Many people have very fuzzy notions of God that are not at all the clear and distinct notion that Descartes claims God to be.[60] Descartes answers this objection, as he often does, by appealing to geometry. Whereas one might not fully understand the nature of circles and quadrilateral figures, which leads one to be mistaken in one’s premises or definitions and, say, suppose that all quadrilateral shapes can be inscribed in circles—thus necessitating that a rhombus can be inscribed in a circle (which is demonstrably false)—so too one might be mistaken in one’s notion of God, leading to irrational conclusions like positing that God’s nature doesn’t necessitate existence. But just as in geometry, the proper conclusions become clear and distinct and unassailable once one fully understands the premises and proper definitions (definitions which are already innately in the mind but not immediately known), so too, when one understands that a first and sovereign being necessitates all perfections and that existence most certainly is a perfection, the existence of God as inseparable from his essence becomes clear and distinct and unassailable in one’s mind. One may not immediately understand all the necessary conclusions one can draw from the nature of a triangle as a rectilinear figure having only three sides, but once one follows the logic, one must conclude that the sum of its three angles is always equal to two right angles. This is also the case with God’s existence being a necessary consequence of God’s perfection, which is his nature.[61] And where could this notion of God derive? It must have come from a formal reality outside the self that is at least as great as the idea. Thus, God being “that than which no greater thing can be thought” necessitates that he exists actually.
In this way, he brings together Thomas’s arguments from causation with Anselm’s ontological argument to show that the conclusion “God exists” is demonstrably true.
Conclusion
Are Descartes’ arguments sufficient to answer Thomas’s critique and rescue Anselm’s ontological argument? Like all arguments in philosophy, that is still up for debate. Because Descartes never explicitly mentions Thomas or Anselm, it’s impossible to know for sure if he consciously set out to defend Anselm in the face of Thomas. Nevertheless, he either wittingly or unwittingly did so, and anyone who seeks to dispute the merits of the ontological argument must do so in the face of Descartes’ defense. For if there is one thing that philosophy calls us to, it is to never rest fighting the first or weakest form of an idea, but to seek out its strongest champion and take up the challenge. And, in the spirit of Anselm, one can affirm that whether one wins or loses, the attempt to grapple with the nature of God and understand who he is and how we come to know him leaves us better able to hold fast to God through faith and affirm his greatness, power, and perfection.
Nathan Johnson is Assistant Dean of Academics and Teaching Fellow at New College Franklin in Franklin, TN. He has an M.A. in Biblical Studies and an M.A. in Theological Studies from Reformed Theological Seminary, an M.A. in Liberal Arts from St. John’s College, and will be completing his Ph.D. in Humanities at Faulkner University this fall.
[1] Anselm, Proslogion, trans. Benedicta Ward, in The Prayers and Meditations of Saint Anselm with the Proslogion (New York: Penguin, 1973), 244.
[2] Some argue that Anselm isn’t strictly speaking providing a rational proof for God’s existence as much as a rational articulation of the nature of God, demonstrating that who God is entails his own existence. But the difference between proof and rational articulation may be so slight as to be irrelevant.
[3] Anselm, Proslogion, 244.
[4] Anselm, Proslogion, 244-245.
[5] Anselm, Proslogion, 245. Kant argues that Anselm fails here because existence is not a quality that partakes of greater or less (one either exists or does not exists), and thus God’s perfection doesn’t entail existence. But Anselm defeats this critique by arguing that God necessarily exists; since nothing else exists necessarily, one can assert that necessary existence is greater than mere existence, and thus the argument from perfection still stands. To see a deeper explanation of how Anselm defeats Kant’s critique, see: Kenneth Himma, “Anselm: Ontological Argument for God’s Existence” in Internet Encyclopedia of Philosophy. https://iep.utm.edu/anselm-ontological-argument/.
[6] Anselm, Proslogion, 246.
[7] Thomas, ST., I, q. 2, a. 1.
[8] Thomas, ST., 1, q. 2, a. 1, ad 1.
[9] Thomas, ST., 1, q. 2, a. 1, ad 2.
[10] Rene Descartes, Meditations on First Philosophy, trans. John Cottingham (Cambridge: 1986), 3.
[11] It must be noted that Descartes had already written his Discourse on Method, where he is a staunch critic of the obscurities of late medieval scholasticism and what he saw to be a jargon-filled method that obscures more than it reveals. This has caused many to embrace a more Straussian reading of Meditations, arguing that Descartes’ letter to the Sorbonne and attempt to prove the existence of God and the soul is a mere ploy to appease those in power by his subject matter while actually attempting to undermine traditional beliefs through his new method. I do not find this interpretation compelling, for it rests on too many unprovable assumptions; at the end of the day, the written text is the final judge of its own arguments.
[12] Descartes, Meditations. It should be noted here that Descartes in a few sentences launches what will become one of the classic criticisms of modern presuppositional apologetics—that while it is true that Scripture is the foundation of the knowledge of God, appealing to it to prove God’s existence to unbelievers is ineffectual, regardless of whether or not it is making use of a virtuous or vicious circle of reasoning. Of course, presuppositional apologetics also makes use of the transcendental argument for God, which Descartes briefly takes up in “Meditation Five”—albeit in only one of its iterations.
[13] Descartes, Meditations, 11.
[14] Descartes, Meditations, 13.
[15] Descartes, Meditations, 14.
[16] Descartes, Meditations, 14. This is a precursor to one of the most effective arguments against Atheistic Darwinism, for if our senses and mind are only designed to help us survive, then we have no confidence that the senses and mind can lead us to anything intrinsically true, but only to ideas that are useful regardless of their truth value.
[17] Descartes, Meditations, 15.
[18] Descartes, Meditations, 15.
[19] Descartes, Meditations, 15.
[20] Descartes, Meditations, 12.
[21] Descartes, Meditations, 25.
[22] Descartes, Meditations, 12. In this, he seems to reject the category of intuitive knowledge of first principles by means of the internal common sense, or he at least restricts this kind of knowledge to few categories.
[23] In this way, a priori reason is logically prior to experience, even if empirical knowledge is temporally prior to a priori knowledge in the order of how we come to know things.
[24] Descartes, Meditations, 11.
[25] Descartes, Meditations, 11.
[26] It is not sufficient to challenge his reasoning by saying that his methodological doubt assumes already the existence of himself or things outside of his mind; this doubt is a precondition for his method to establish his premises, but not a precondition for the premises themselves.
[27] Descartes, Meditations, 16.
[28] Descartes, Meditations, 17.
[29] Descartes, Meditations, 18.
[30] Descartes, Meditations, 21-22.
[31] Descartes, Meditations, 24.
[32] Thomas, ST, I, q. 2, a. 3.
[33] Descartes, Meditations, 24.
[34] Descartes, Meditations, 26.
[35] Descartes, Meditations, 26.
[36] Descartes, Meditations, 26-27.
[37] Descartes, Meditations, 27.
[38] Descartes, Meditations, 27.
[39] Descartes, Meditations, 28.
[40] Descartes, Meditations, 28.
[41] Descartes, Meditations, 28.
[42] Descartes, Meditations, 29.
[43] Descartes, Meditations, 29.
[44] Descartes, Meditations, 29.
[45] Descartes, Meditations, 29.
[46] Descartes, Meditations, 29.
[47] Descartes, Meditations, 31. It must be noted that he does not persuasively argue that all corporeal elements could be sourced in the self. In fact, he almost undermines his own argument that he can only be certain of being a thinking thing, for he admits that if he were solely mind, corporeal elements of extension, shape, position, and movement cannot exist formally within him. Yet, he maintains that these are “merely modes of a substance” and since mind is a substance, these ideas could be “contained in me eminently.” This seems suspect and it rather argues for the fact that either he must also be a corporeal being or that these ideas exist formally outside his mind. Nevertheless, this is not essential for his argument for the existence of God, even though it calls into question his other main claim about the primacy of the mind.
[48] Descartes, Meditations, 31. In this definition he differs from Anselm in that he doesn’t posit existence as one with God’s essence, at least at this point in the proof; nevertheless, by arguing God’s perfection he assumes existence as an aspect of perfection. While parts of his proof are similar to Anselm’s—particularly the notion that, since God can be thought, he must exist—his proof in “Meditation Three” is also different because God’s existence isn’t part of the definition of the idea of God. Yet, in “Meditation Five” he does produce an ontological argument for God which is very similar to Anselm’s, but this is only after he establishes that everything “clearly and distinctly” known must be true, a claim he proves in “Meditation Four.” Perhaps his reason for withholding existence as part of the initial definition is so that he can focus on the argument for causation without distracting the reader by the argument from definition. In this way, he clearly answers Aquinas’ challenge of the ontological argument before he puts it forward in “Meditation Five.”
[49] Descartes, Meditations, 31.
[50] Descartes, Meditations, 31.
[51] Descartes, Meditations, 30-31. One of the famous objections is that the idea of infinity is actually a negation—the negation of a boundary—which means that we understand the idea by means of our experience of finitude. But Descartes replies that finitude is actually a negation of the infinite, for all limitation is understood as negation. Thus, infinitude and perfection are prior to finitude and imperfection. Ibid., “Fifth Replies”, 81.
[52] Descartes, Meditations, 32.
[53] Descartes, Meditations, 32-34.
[54] Descartes, Meditations, 34.
[55] Descartes, Meditations, 35.
[56] Descartes, Meditations, 35.
[57] Rene Descares, Meditations on First Philosophy, trans. Norman Kemp Smith, in The European Philosophers from Descartes to Nietzsche (New York: Random House, 1992), 62.
[58] Descartes, Meditations, 62.
[59] Descartes, Meditations, 63.
[60] Thomas Aquinas, ST 1, q. 2, a. 1, ad 1.
[61] Descartes, Meditations, 63-64.