Descartes’ Meditations on First Philosophy 9


More on Proving the Existence of God—The Fifth Meditation

More on Proving the Existence of God—The Fifth Meditation

§ 1: What is the Fifth Meditation out to accomplish?

Like the Third Meditation, the Fifth Meditation is hard to understand—this time, however, not because it is hard to understand the argument Descartes gives but because it is hard to see just why Descartes engages in the argument at all. The title of the Meditation indicates that he wants to provide another argument for God’s existence. But why Descartes should feel the need for a second proof, given that he has already provided one in the Third Meditation, is not easy to explain. The title of the Fifth Meditation indicates, however, that Descartes also wants to discuss the essence of material things. This latter concern, when interpreted properly, reveals, I think, why Descartes wants to provide another proof of God’s existence, indeed why he wants to provide the kind of proof he does here. For this proof is, as Clarke points out—see note 17, p.205—a rehash of a various famous or rather infamous proof of God’s existence, namely, the ontological proof of his existence. This is called the ontological proof because it attempts to deduce God’s existence from what it is to be God, i.e., from the being or essence of God.

In fact, in order to understand why Descartes wants to provide a second proof of the existence of God, moreover, a version of the very traditional ontological one, we should begin with another puzzling issue. In the opening paragraph of the Fifth Meditation Descartes notes that there are still many things to consider about the nature of God and his own mind. That is, there are many attributes which he has thus far not shown to be possessed by God and by his own mind. He decides, however, to defer these issues in order to consider how he can have any certainty about material things. (p.51) But why should he need to consider this issue of how he can have certainty about material things? Surely, having proved the existence of non-deceptive God, Descartes must now already know that he really does have reliable perceptual experience. And if he knows himself to have reliable perceptual experience, then he knows that most of the judgements he derives from perceptual experience are true and that those which are false he can mostly discover to be false, hence can correct. So surely he already knows, thanks to the proof of the existence of God in the Third Meditation, that there are the material things which present themselves to him in his perceptual experience. Why should Descartes think, as he apparently does here, that he does not yet have certainty about material things?

Now it seems to me that in order to see what Descartes is getting at here, we must appreciate that Descartes says that he does not yet have certainty about material things, not that he does not yet have certainty about the existence of material things. This suggests that Descartes is not here concerned about the question of whether there are the material things of which he seems to have reliable perceptual experience; rather, he is concerned here about what it is to be a material thing of the kind he seems to have reliable perceptual experience of. In other words, the certainty he regards himself as not yet having concerns not whether material things exist but what they are. To use the kind of language Descartes himself might use, the certainly he does not yet have is certainty, not about the existence, but about the essence of material things.1

In particular, Descartes does not yet know what the essence or fundamental nature of material things must be if they are to be knowable. God’s existence guarantees that the material things he thinks exist really do exist. But in order for material things to be known by Descartes, they must not merely exist, they must also be knowable. So in addition to the task of establishing that material things exist (which involves proving the existence of God), Descartes confronts the further, independent task of establishing what makes material things truly knowable, that is to say, in a truly, systematic way, such that one can construct scientific theories about them. Just this task lies behind Descartes’ expressed concern to ascertain the essence of material things, i.e., their fundamental ontological nature. For as Descartes understands the notion of essence, the essence of something is what it truly is, whereby what it truly is that in virtue of which it can be the object of successful systematic, indeed unified theoretical description and explanation.2 Now according to Descartes, material things are only truly knowable, such that one can construct systematic, unified theories about them, if the principle of clear and distinct perception to applies to them—that principle which Descartes first articulates in the Third Meditation, which he knows from the outset to be valid in the one special case of his knowledge of himself as existing and as thinking and of which he says in the Third Meditation that he wishes to establish it as a general rule applying to material things—see p.31.3 So the essence of material things must be such as to ensure that the principle of clear and distinct perception can be systematically and coherently applied to them.

In § 2 I describe what Descartes sees as the essence of material things, understood as what guarantees the knowability of them. But already we see this much, namely, why Descartes is concerned in the Fifth Meditation to determine the essence or fundamental ontological nature of material things. Unfortunately, this does not help us with the much thornier question of why Descartes feels the need to provide a further proof of God. It seems to me, however, that the key here lies in taking seriously the fact that, as the Fifth Meditation itself makes clear, Descartes is assuming from the outset that he has already shown the existence of God: the Fifth Meditation begins with the decision to stop contemplating the attributes of two things which Descartes by now clearly regards himself as entitled to assert as existing, namely, his own nature or mind and God. Similarly, the Fifth Meditation itself makes clear that Descartes already regards himself as entitled to assert as a general rule, that is to say, for all cases of its seeming clearly and distinctly to him that p,4 that if it seems clearly and distinctly to him that p, then he may rationally judge that p.5 Thus, right in the middle of the Fifth Meditation he says, “But whatever argument I eventually use to prove something, I am always brought back to this: the only things that clearly convince me are those that I perceive clearly and distinctly.” And later he says, ““But once I [had] perceived that God exists and … also understood, at the same time, that everything else depends on him and that he is not a deceiver, I concluded that all those things that I clearly and distinctly perceive are necessarily true.” (p.56) There seems no reason to conclude, simply from the fact that this passage occurs after he has given his version of the traditional ontological proof of God’s existence, that Descartes is not referring to an insight he understands himself to have attained already in the Third Meditation.

If, however, Descartes shows himself, precisely in the Fifth Meditation, to be quite happy with his proof of God’s existence in the Third, what reason could he have for providing a second proof of the existence? Note that the ontological proof of God’s is a very long-standing, traditional kind of proof, precisely the kind of thing those most learned and distinguished gentlemen of the Sorbonne were adept in formulating. As such, it had already been subject, well before Descartes’ time, to much critical reflection and to various kinds of long-standing, traditional objection. One such long-standing, traditional objection is adduced precisely by Descartes himself, immediately after he has presented his version of the argument. Descartes introduces this objection to his own argument when he says, “However, it is clear that this is not perspicuous at first sight and it seems to be some kind of logical trick.” (p.53) Descartes then sets about defusing this objection by appeal to a distinction implicit in his discussion of mathematical or rather geometrical ideas on p.52, which are, he claims, ideas of entities which “have their own true and immutable natures.” (p.52) Roughly speaking, the reply to the objection is that the idea of God is like the idea of a triangle, i.e., the idea of something with a true and immutable nature and for this reason the objection fails. And not merely does this objection fail; once the idea of God is understood properly, one gets to understand the ontological argument properly. This is seen not to be so much a proof of God’s existence as an inadequate, inept way of understanding God, and in particular, God’s unique status as something whose essence cannot be separated from its existence.

I spell this out in greater detail in §§ 3 and 4. For the moment, however, the crucial thing to note is the general upshot of all this: Descartes introduces his version of the traditional ontological argument as part and parcel of a process of correcting the traditional misunderstanding of it. If this is right, then Descartes adduces his version of the ontological proof not in order to prove for a second time the existence of God (which would be superfluous) but to reveal what this traditional style of argument, practised as it is by the theologians to whom Descartes is addressing his Meditations, really is.

§ 2: Descartes on the Essence, hence Knowability, of Material Things

Previously, Descartes had maintained that God ensures the existence of the material things he thinks he perceives. But as we have seen above, he must give an account of this because merely ensuring that material things exist does not account for their knowability in the strong sense intended by Descartes, namely, comprehension in and subsumption under a systematic, unified theoretical account of the natural world.6 Independent of the task of showing that material things is thus the task of identifying what it is about them which constitutes their essence and thus the basis of their knowability. Now Descartes wants to show that the knowability of material things—and by this Descartes means their capacity to be objects of systematic, unified theoretical description and explanation—restricts one to a specific understanding of their essence.

Descartes very quickly makes clear what he regards this essence as. In the second paragraph of the Fifth Meditation he decides to inspect his ideas of material things in order to determine which of them “are distinct and which are confused.” (p.51) And then, in the third paragraph, he goes on to speak solely of those of the ideas he applies to material things which are quantitative:

I have a distinct image of quantity, which philosophers usually call continuous quantity, or of its extension, or preferably, of the extension of a quantified thing in length, breadth and depth. I also pick out various parts in it and assign to these parts various magnitudes, shapes, positions and local motions, and I assign various durations to the local motions. All these things, considered in this general way, are not the only things that are clearly perceived and known; by paying attention I also perceive innumerable particular things about shapes, number, motion and so on, the truth of which is so open and accommodated to my nature that, when I first discover it, I seem not so much to learn something new as to remember things I already knew or to notice for the first time things that were in my mind for a long time even though I had not previously turned by attention to them.7 (pp.51-52)

In other words, only the ideas or concepts he has of the quantitative aspects of a material thing are those he grasps clearly and distinctly. These are the essence of any material thing, hence definitive of his idea or concept of a material thing—so definitive, in fact, that he did not first have the concept of a material thing and then only subsequently discover that, as a matter of further, brute fact, material things are extended, hence have “various magnitudes, shapes, positions and local motions,” but rather this quantitative character came with his concept of a material thing itself. The essence of a material thing lies in its quantitative character, its character precisely as res extensa, i.e., an extended being. Being extended is so inherent to, so definitive of, a material thing, that the idea of extension is not just contingently in the idea of a material thing, but necessarily or inseparably so. And only for this reason is a material thing knowable in the strong sense that there can be a systematic, unified theoretical descriptive and explanatory account of it.

§ 3: Inherently Complex Ideas versus Compositionally Complex Ideas

So much, then, for the issue of what the essence, hence knowability, of material thing is. There is, however, a further point Descartes is trying to make here, one which is crucial for understanding how Descartes thinks about his idea of God and thus for understanding just why he adduces his own version of the traditional ontological proof of God’s existence. This further point concerns the nature of our mathematical and geometric ideas, which he discusses across the remaining two paragraphs on pp.52-53. Such ideas have a certain complexity: Descartes can extract from his idea of a triangle, for example, the idea that the sum of its angles is two right angles, i.e., 180 degrees. This idea is necessarily contained with the idea of a triangle, such that one does not need any experience in order to know that the sum of the angles of a triangle is 180 degrees—as if one had empirically to establish, say, by measuring the sums of the angles of actual triangles drawn on blackboards and the like, that whatever instantiates one’s idea of a triangle also an instance of the idea of being something whose angles sum to 180 degrees. This is obviously a caricature of how one knows, or comes to know, that a triangle is something whose angles sum to 180 degrees—not just because actual triangles drawn on blackboards would be so roughly drawn that their angles would not sum to 180 degrees but also because this empirical procedure would fail to capture the necessity of what one knows. The various properties of a triangle can be demonstrated by non-empirical geometric proof to be necessary.

Now in discussing his mathematical and in particular his geometric ideas, Descartes makes an observation which is crucial to understanding his account of such ideas and which points to a distinction Descartes draws, admittedly only implicitly, between ideas. Of his mathematical and geometric ideas Descartes says that “they are not … invented [i.e., composed or put together] by me and … have their own true and immutable natures.” (p.52) As we have seen, there is a certain complexity built into the idea of a triangle: from the idea of a triangle one can extract the idea of being something with threes, being something whose angles sum to 180 degrees, or again, being something whose surface area equals half the product of the length of the longest side and the length of the perpendicular extending from the longest side to the point at which the other two sides meet, etc. And when Descartes says that his mathematical and geometric ideas are not invented by him but have their own true and immutable nature, he is intimating that this complexity is inherent; it is not there in virtue of any process of composition or fabrication. In other words, Descartes’ mathematical and geometric ideas come with their complexity built into them from the outset.

Many of Descartes’ ideas are not like this; they are or at least could be the result of definition or stipulation, they have been literally composed out of simpler ideas. Take such ideas as those of a bachelor, a centaur or a unicorn. A bachelor is an unmarried male. A centaur is a mythical creature with the head, torso and arms of a man and the body of a horse. A unicorn is a horse with a single horn on its nose. So these ideas are clearly complex; as with the idea of triangle, one can deduce certain things from them, e.g., from the idea of a bachelor, the idea of someone male, etc. Perhaps no one consciously composed or fabricated these ideas, in an act of definition or stipulation. Nonetheless, these ideas have arisen through composition or fabrication out of pre-existing ideas, viz., ‘male’, ‘unmarried’, possibly ‘human being’; or again, the various ideas associated with the ideas of human torso and an equine body, etc. For example, our ideas of a centaur and a unicorn have emerged out of various practices of myth-making, which have simply combined the relevant component ideas into single, complex idea.

We now have a distinction between ideas which are inherently complex, which have their complexity from the outset; and ideas which have their complexity by composition, such that one can speak of the idea’s being put together out of ideas the mind already has. The relevance of this distinction becomes apparent once Descartes moves on to introduce his own version of the famous ontological argument for the existence of God. Descartes introduces his version of this kind of proof with the following rhetorical question: “Now if it follows, from the fact alone that I produce an idea of something from my thought, that everything that I perceive clearly and distinctly as belonging to it does really belong to it, could I not also derive an argument to demonstrate God’s existence?” (p.53) Note the clause “that I produce an idea of something from my thought”. Here, Descartes appears to be insinuating the notion of a complex idea whose complexity arises through composition out of pre-existing ideas. And it is surely true that if the idea in question is a compositionally complex one, then whatever seems to me clearly and distinctly to belong to it must belong it. Consider the idea of a bachelor. Surely to understand this idea just is to know that something is a bachelor just in case it is an unmarried male. So it does follow that, for any compositionally complex idea which Descartes grasps, everything he perceives clearly and distinctly as belonging to it does really belong to it. And now Descartes rhetorically asks whether this might not suggest a way of proving the existence of God.

In other words, the line of thought Descartes is intimating here is the following: if the idea of God is a compositionally complex one, then one can derive an argument for God’s existence which consists in extracting the idea of existence from the idea of God in just the same way as one extracts the idea of being male from the idea of a bachelor, or again, the idea of having a human head from the idea of a centaur. Descartes then goes on to provide just such an argument, precisely an ontological argument for the existence of God. I will outline and analyse this argument more closely in the next section. For the moment, the crucial thing to note is that once he has presented his argument, Descartes immediately goes on to make an objection to his argument. He says, “However, it is clear that this is not completely perspicuous at first sight and it seems to be some kind of logical trick.” (p.53) And the reason why Descartes suspects there to be a logical trick in the argument he has presented has to do with the assumption which guided his construction of it, the assumption, namely, that his idea of God is compositionally complex, in strict analogy to his ideas of a bachelor, a centaur or a unicorn. If one regards the idea of God as a compositionally complex one like the idea of a bachelor, a centaur or a unicorn, one proves at most that the idea or concept of existence is contained within the idea or concept of God, not that the idea or concept of existence applies to anything which could qualify as instantiating the idea or concept of God. (Analogously, by proving, on the basis of an analysis of one’s concept of a bachelor, that the concept of a male is contained within it, one merely shows that if something is a bachelor, then it is a male; one does not show that there actually is anything which is a bachelor.)

I will explain all this in greater detail in the next section, in which I present and dissect Descartes’ version of the ontological argument. For the moment, the point I want to make concerns the strategy Descartes is pursuing in presenting his argument and then his objection to it. For I suspect that in introducing, presenting and criticising his version of the ontological argument in the way he does, Descartes is recapitulating how he thinks the ontological argument has arisen historically, in Scholastic philosophy. In particular, Descartes is intimating that traditionally the ontological argument has been understood as plausible and possible on the basis of the assumption that the idea of God is compositionally complex, which understanding of the argument has then provoked precisely the kind of objection which Descartes describes as a logical trick. For indeed this objection had been raised before to the ontological argument, indeed it is raised by one of the people from whom Descartes solicited objections, viz., the priest Johan de Kater, otherwise known as Caterus, which is the Latin form of the name ‘de Kater’—see pp.71-72 of the Clarke translation.8

This immediately suggests that in presenting his version of the ontological argument, Descartes is indeed not at all interested in providing a second, stand-alone proof of the existence of God but rather with showing that the ontological argument, as traditionally understood, rests on a misunderstanding of the idea of God which, once corrected, not only defuses a traditional objection but identifies what is legitimate about the ontological argument. In particular, correction of this misunderstanding shows that while the ontological argument must be chronically question-begging when understood as a simple deduction or inference, it nonetheless reflects, if only inadequately, insight into a logical feature unique to the idea or concept of God. This unique logical feature is that in God’s case one cannot separate essence and existence from one another. Or, to put the point in another way, correction of this traditional misunderstanding of the idea of God and thus of the ontological argument itself shows that the idea of God is unique in that it is an idea one cannot understand without committing oneself to it as instantiated. It is this feature of the idea of God which traditional theologians have been seeing through a glass but darkly when, in what we shall soon see to be the second premise of the ontological argument, they have said such things as that existence is a perfection or that God’s existing makes Him greater than His not existing. In fact, in the end the whole ontological argument shows itself to be an inchoate way of making the good point that, as the Third Meditation has already shown, commitment to the existence of God is inherent to one’s indubitable, unshakeable commitment to one’s own existence as thinking—this because to understand that one exists as thinking is to understand oneself as existing as doing in imperfect, limited fashion what that cause of one’s idea of God does perfectly and without limitation.

§ 4: Descartes’ Version of the Traditional Ontological Argument

Descartes provides his version of the traditional ontological argument in the following passage:

Certainly I find in myself an idea of God—that is, of a supremely perfect being—just as much as I find an idea of any shape or number. I understand that it belongs to God’s nature [as a supremely perfect being] that he always exists, as clearly and distinctly as I understand that whatever I demonstrate about any shape or number belongs to the nature of that shape or number. Therefore, even if everything on which I [have] meditated in recent days were not true, I should attribute to God’s existence at least the same degree of certainty that I have attributed to mathematical truths until now. (p.53)

A careful reading of this shows that by abstracting away from Descartes’ references to finding an idea of God in himself, we get the following set of premises and conclusion:

  1. God is a supremely perfect being, that is, has all perfections

  2. Existence is a perfection

∴ God has existence, that is, exists

This shows that Descartes does have in mind an ontological argument of the standard kind. The first known formulation of the ontological argument for the existence of God stems from St. Anselm (1033-1109), Archbishop of Canterbury and a famous theologian. Anselm put matters as follows:

1.* God is a being greater than which nothing can be conceived

2.* If God existed only in our minds, i.e., if nothing in reality corresponded to our concept of God, then God would not be a being greater than which nothing can be conceived (since His existing makes Him greater than His not existing)

∴ God exists not just in our minds, but in reality.

But having presented his argument, Descartes immediately goes on to make an objection to it. “However, it is clear that this is not completely perspicuous at first sight and it seems to be some kind of logical trick.” (p.53) It seems that the ontological argument indulges in an egregious sleight of hand: it attempts to deduce the existence of an instance of an idea or concept from the putative fact that the concept contains the concept of existence as a necessary component idea. Surely this is crazy: the concept of being a male is contained in the concept of being a bachelor, but all that this entitles one to deduce is that if something is a bachelor, then it is male. So mutatis mutandis all one can derive from the idea or concept of God, given that this idea or concept contains the idea or concept of existence is that if something is God, then it exists. And from this conditional one cannot derive that there is anything which is God, no more than one can derive from the conditional “If something is a bachelor, then it is male” that there is something which is a bachelor.

Now it seems to me that Descartes wants to show how to get around this objection. In particular, he wants to show that it rests on an incorrect understanding of the idea or concept of God he finds himself, indeed according to Descartes, cannot but find himself. The ontological proof, at least as traditionally conceived, understands the concept of God as if it were just one more concept amongst many others. In particular, it assumes that this idea or concept is an idea or concept just like those of bachelor, centaur and unicorn. More precisely, it fails to see how Descartes’ idea or concept of God differs radically from such merely compositionally complex concepts. The point of Descartes’ initial discussion of his quantitative ideas of a material thing is to lead us into a discussion of what his mathematical and geometrical ideas are (across p.51 through to the top of p.53). And the point of this discussion of his mathematical or geometric ideas is to enable us to see that these are complex ideas whose complexity of content is inherent rather than merely compositional. They are thus ideas one can neither produce by definition nor acquire by empirically discovering an instance of it.9 And Descartes discusses his mathematical and geometric ideas in order, I think, to suggest that they provide a model for thinking of the way in which his idea of God is complex: the complexity of his idea of God is similarly is inherent. Moreover, it is inherently complex for the same reason.

Let us now look at the account Descartes gives, prior to introducing his version of the ontological argument, of his mathematical and geometric ideas. He says that he finds within himself ideas of quantity, i.e., number, and ideas such as that of a triangle. And these ideas are not ‘arbitrary’ ideas, like his ideas of a bachelor, a centaur or a unicorn, which are precisely ideas produced from thought—see p.53. Rather, his ideas of number (‘quantity’) and shape are much more basic and fundamental. In particular,

(a)lthough I think about them to some extent by choice, they are not, however, invented by me and they have their own true and immutable natures. For example, when I imagine a triangle, even if it were true that no such figure exists or has ever existed anywhere outside my thought, it still clearly has some determinate nature or essence or form, immutable and eternal, which was not constructed by me and does not depend on me. This is clear from the fact that various properties of the triangle can be demonstrated; for example, that its three angles are equal to two right angles, that the longest side is subtended by the biggest angle, and similar properties. Even if I [had] never thought of them previously when I imagined a triangle, I now know them clearly independently of whether I wish to or not and therefore they were not invented by me. (p.52; grammar corrected)

But why is it that words like ‘number’, ‘quantity’, ‘triangle’, etc., do not express complex ideas which are merely ‘arbitrary’ combinations of simpler ideas? Why is it that each of these complex idea express what Descartes calls a “determinate nature or essence or form, immutable and eternal …” which he has not constructed? Descartes does not really explain what it means to describe a triangle as having, hence the idea of a triangle as expressing, a determinate and immutable nature. Presumably, Descartes understands this as follows: an idea expresses a determinate and immutable nature insofar it is a necessary component or implication of some powerfully explanatory true theory about an aspect of reality. Thus, the idea or concept of a triangle is a necessary component of a certain powerfully explanatory geometrical theory which can be captured in a certain set of axioms, which set of axioms will entail that there are entities possessing such properties as having three angles, or alternatively, having three sides, or even (if the geometrical realm to which the axioms apply is a Euclidean space) having angles which sum to 180 degrees. In this sense, then, there is, prior to the introduction of the word ‘triangle’, something there for the word to denote, viz. the triangle in Euclidean space, and this will indeed have a diversity of different, mutually entailing properties.

By contrast, the idea or concept of a centaur has arisen simply through combining the ideas of having the upper body of a man and of having the lower body of a horse. Similarly, although there obviously are bachelors in a way there are not any centaurs, the idea or concept of a bachelor has arisen through combining the ideas of being male and being unmarried. In no sense is either of these concepts a genuinely theoretical one belonging to or implied by some set of powerfully explanatory theoretical claims (axioms) which characterise a certain domain of reality for what it is. The unity of the complex ideas of a bachelor and a centaur is in this sense a purely contingent, ‘arbitrary’ one which is founded, not in reality, but in the fact that we find useful to wield such concepts in our practical affairs. In this sense, these ideas or concepts do not express true and immutable natures.

Importantly, those ideas or concepts which, because they are important theoretical concepts, possess an inherent complexity10 will plausibly possess another essential feature: their complexity, hence the diverse ideas they contain, will not be immediately available to the mind of someone who possesses the idea but must rather be spelt out in careful reflection on them. Whereas anyone who can effectively wield the concept of a bachelor knows that a bachelor is unmarried male (and this is in fact all one can extract from this concept), many can wield the concept of a triangle quite adequately without knowing many of the things, of which there are quite a number, which follow necessarily from something’s being a triangle. In other words, complex ideas whose complexity is inherent because they are theoretical concepts which express true and immutable natures, have a depth-dimension to them which the mind does not grasp all at once, but which it can only comprehend by exploring the idea or concept and unpacking its hidden content. Compositionally complex ideas are ones the understanding of which just is the grasping of the relatively few simpler ideas which make it up. But inherently complex theoretical ideas are ones of which one can have an initial, superficial understanding and then go on to acquire a richer, deeper understanding, as one explores the many more aspects of its content.

Now Descartes wants to maintain that his idea or concept of God is also inherently complex, hence is a theoretical notion quite unlike his ideas of a bachelor or a centaur. So his idea of God has a depth-dimension to it, such that the entirety of its content is not transparent to the mind, or grasped by it, from the outset.11 Moreover, as inherently complex, it is a theoretical notion, that is, part of a powerfully explanatory theory. In this case, the theory is a philosophical and theological account of God and His creation, in all its aspects. This philosophical and theological account consists in particular in a characterisation of how God is causally related to the world and all the finite, created beings in it. At this point, we can make sense of an otherwise rather mysterious part of the Third Meditation. Notice how by p.40 in the Third Meditation Descartes appears to have proved to his satisfaction the existence of God but then goes on to say that when he examines his proof less carefully, “and when images of sensible things blind the eye of the mind” (p.40), he does not easily remember why the idea of being more perfect than himself comes from some other being more perfect in its (formal) reality than he. He then says that this gives one reason to inquire further into whether he, as a finite thinking thing, could exist if no such more perfect being existed. When one first encounters this passage, it seems entirely obscure. But I think a proper understanding of what is going on in the Fifth Meditation helps us to understand this passage in the Third: by p.40 Descartes has shown that God, that most infinitely powerful and beneficent Being upon which Descartes is dependent not just for his idea of God but for his very existence as a being capable of self-conscious, first-person awareness of itself as existing and as thinking. But what exactly is this dependence? That is, what does God’s power and goodness consist in? How exactly does Descartes derive his very existence from God?

The strange passage across pp.40-42 is, I think, meant to answer these questions, that is, to explain, not that an infinitely powerful and beneficent being exists to which Descartes owes his entire existence (since this has already been accomplished), but rather what it means to say that such a being exists, and in particular, what it means to say that this infinite being sustains such a finite being as Descartes himself. Recall what Descartes says across about the way he, as a finite being, derives his existence from God. He does not derive his existence from God in the way he has derived his existence from his parents, viz., through an act of creation at a point in time which brought Descartes into existence and then had nothing more to do with him. No, Descartes derives his existence from God continually. In God’s case creation is conservation: God works in the world by sustaining Descartes as one and the same individual, viz., Descartes, across time, that is, by securing Descartes’ persistence across time. And God does this for all other finite, created beings, indeed for the entire created world. This sustaining of the world just is God’s creating of the world.

Furthermore, having argued (pp.41-42) that his own existence and, mutatis mutandis, that of every other finite, created thing derives from God in the sense that God sustains them all in their identity across time, Descartes goes on to argue (p.43) that thus conceived, God could not be a deceiver. The argument here runs as follows: his initial certain knowledge that he is as thinking is awareness “not only that I am an incomplete and dependent being and that I aspire indefinitely towards what is greater or better … .” It is also at the same time awareness

that he on whom I depend is greater than all those things, not just indefinitely or potentially, but that he contains them all to an infinite degree in himself is and is thus God. The whole force of this argument consists in the fact that I recognize that it is impossible for me to exist with the kind of nature I have, that is, having in myself the idea of God, if God did not truly exist. I mean the God of whom I have an idea, that is, who has all those perfections that I cannot comprehend but is such that I can reach him in some way through my thought and is clearly immune from all defects. It follows clearly enough that he cannot be a deceiver, since it is evident by the natural light of reason that every fraud and deception results from some defect.” (p.43)

It is not exactly clear how this argument is meant to work. One thing is clear: Descartes is once again driving that point home that his knowledge of himself as thinking is knowledge of himself as doing imperfectly across the board what the cause of his idea of God does perfectly. Since being deceptive is a defect, an imperfection, it follows that his awareness of himself as thinking entails the existence of a being which is not only supremely powerful (in that it sustains him in existence) but does so beneficently, such that it would not deceive. Notice, however, in all this Descartes appears to be implying something rather distinctive about his idea of God: this is the idea of that supremely powerful, beneficent being which sustains him in existence and which Descartes grasps as thus sustaining him in existence in his very awareness of himself as existing as thinking. The idea of God thus turns out to be a very distinctive, special theoretical concept: it is an idea in understanding which Descartes understands it as exemplified.

This enables us to make sense of something which Descartes says immediately after speaking of how his ontological proof seems to be some kind of logical trick. For here he speaks of how he is “used to distinguishing existence from essence in everything else.” In speaking here of a distinction between essence and existence Descartes is simply distinguishing, in the manner of Scholastic philosophers of the Middle Ages themselves, between what a thing is—precisely its essential nature—and that it is, i.e., the fact of its existence. And on the essence is one thing, existence is another: that the essence of anything is such and such surely does not entail that there actually exists anything with or of this essence. As we have seen, the essence of material things lies according to Descartes in their quantitative properties and relations. But this fact obviously does not entail that there actually are material things.

Notice, however, that Descartes has in effect argued that his idea of God constitutes an exception to this general point: his inescapable, indubitable grasp of himself as existing as thinking is a grasp of himself as doing imperfectly what that entity which instantiates his idea of God necessarily does perfectly. And so, since Descartes cannot but grasp himself as existing and thinking, he at the same time cannot but grasp his idea of God as applying to something which actually exists. In effect, he claims that he discovers that his having an idea of God and understanding at least something of what is contained in it goes hand in hand with understanding this idea as instantiated. In other words, Descartes’ idea of God articulates an essence which he cannot understand except as that of an existent. In God’s case, and God’s case alone, what something is implicates that it is, at least in the sense that one cannot claim to understand this essence without grasping it as existing, as the essence of something real.

If this is right, then we can now see Descartes as having given an explanation of the intuition underlying the second premise of the ontological argument, namely, that existence is a perfection. On the face of it, it is just false to assert this as a general principle, for surely the existence of Hitler is manifestly not better than his non-existence. But we can see Descartes as arguing that this premise, and with it the whole ontological argument, is an inept way of understanding the idea of God in its peculiar nature. For it is clear, claims Descartes,

to whoever thinks about it more carefully that existence can no more be separated from God’s essence than one can separate, from the essence of a triangle, that the three angles are equal to two right angles, or than one could separate the idea of a valley from the idea of a mountain. Thus to think of God (that is, a supremely perfect being) as lacking existence (that is, lacking some perfection) is just as contradictory as to think of a mountain that lacks a valley. (p.53)

Here Descartes is indeed saying that the distinctive feature of the idea of God, or rather, of God himself, is that one cannot think the idea of God without thinking of it as instantiated. Of course, if this is right, then the ontological argument is not really an argument, a proof at all; it is rather an inchoate, unclear explication of the concept of God itself. And so it cannot be the case that when Descartes introduces his version of the ontological argument, he sees himself as providing an additional, stand-alone proof of the existence of God. Rather, he seems himself as showing that when the traditional ontological argument is understood as an argument, it not only does not demonstrate what it claims to demonstrate, it also presupposes a distorted understanding of our idea of God and how both this idea and God himself make our existence as thinking things possible.

That this is the right way to understand Descartes is indicated by the way he replies to Caterus on pp.74-77. As already pointed out, Caterus objects that the ontological proof is indeed a logical trick in the sense discussed above, namely, a non sequitur in which one mistakenly infers from a property possessed by the concept of God (viz., containing the idea or concept of existence) to the existence of something instantiating the concept. To this objection Descartes replies in two steps, neither of which are particularly clear. First, he appears to argue that Caterus treats the concept of God as if it were a concept just like any other, which one could have before one’s mind and contemplate without taking any stance on whether the concept is instantiated. But, or so Descartes argues, this is to fail to understand the specific sense in which existence belongs to the essence of God. As Descartes puts it, the objection fails to appreciate adequately “the extent to which existence belongs to the essence of God more than in the case of other things.” (p.75) What could he be getting at? In the next paragraph of his reply to Caterus, Descartes claims that

we need to distinguish between possible existence and necessary existence, and we should note that possible existence is contained in the concept or idea of everything that is clearly and distinctly understood. However, necessary existence is contained only in the idea of God. (p.75)

Here, Descartes first points out that when we understand any concept or idea, provided only that it is coherent, we understand it as possibly applying to something, as possibly having an instance. But then he claims that when we understand the idea of God, we eo ipso understand it as actually applying to something, as actually having an instance. If this is right then the idea of God is a truly unique idea in that we cannot truly grasp it without committing ourselves to its being instantiated.

There is a tendency in the literature, amply illustrated by Dicker, to treat the Ontological Argument in the Fifth Meditation as if it were just Descartes’ attempt to copy what Anselm and others had done before him – as if Descartes’ argument were a stand-alone argument which was independent of everything else that had gone in the Meditations up to this point. This is how Caterus treats the argument of the Fifth Meditation – as if one could understand and analyse it independently of the previous Meditations. But Descartes is indicating in his reply that this is not how it is to be understood.

I think Descartes’ reasoning is as follows: if the concept of God were just like any other concept, then one could have it before one’s mind and wonder whether anything instantiated it. To do this is, however, to assume that the idea can be clearly and distinctly understood while attributing it merely possible instantiation. And the previous argument of the Meditations, in particular, the Third Meditation, has ostensibly shown this to be the wrong way to think about the idea of God. In all other versions of the Ontological Argument something is left unexplained, namely, just why existence is to be regarded as a perfection, at least in God’s case. It is, after all, not obvious why existence should be a perfection or, for that matter, an imperfection. In what sense is it a perfection that Adolf Hitler should have been actual rather than merely possible? If one is thinking of Hitler, then, if it all makes sense to speak of perfection and imperfection with regard to existence, surely we must say that existence is an imperfection. In other words, surely talk of existence as perfection only makes sense relative to what is said to exist: if a being like Hitler, then it is an imperfection, if a being like God, a perfection.

In what sense, then, might the existence of God be a perfection? Here we must remember that for Descartes’ purposes it will not do to say that God’s existence is a perfection just because He is a nice guy, or even the nicest guy conceivable. For this does not explain how it could ever be the case that to think the concept of God is to think this concept as applying to something. But we find in the Third Meditation some clues as to a sense of perfection which better fits the bill: His existence perfects human existence in the sense that human thinking is something a human being can only recognise as thinking and ascribe to itself as its thinking insofar as it understands its activity as limited version of something undertaken by that infinite cause of its idea of God, an infinite cause which acts as guarantor for the success of all finite versions of this activity. If this is true, then no human being like Descartes can grasp itself (as thinking) without grasping the existence of the supremely perfect being, God. This is why, in all versions of the Ontological Argument, up to and including Descartes’, existence is asserted to be a perfection. But only in Descartes’ version of the argument is the true basis for this premise properly understood: this is asserted as a premise in all versions of the argument because it reflects awareness of the way any created mind such as Descartes’ can be brought to see, by following the kind of reasoning in which Descartes engages in his Meditations, that its certain grasp of itself as existing is, when unpacked a little further, at the same time grasp of God as existing.

If this is the right way to read Descartes’ response to Caterus, then we need to see the Ontological Argument of the Fifth Meditation as deeply integrated into the dialectical structure and argument of the Meditations overall. For what Descartes is in effect doing here is showing a Christian audience, in particular, an audience of Christian theologians, how properly to understand the role of the concept of God, and indeed commitment to God, as a constitutive element of self-conscious subjectivity. The Ontological Argument as Descartes understands it is not there to provide independent proof of the existence of God, presupposing all sorts of potentially question-begging assumptions about the distinctive status of the concept of God (as a concept for which the usual distinctions between essence and existence do not hold). Rather, the Ontological Argument as Descartes understands it is there to provide evidence for the distinctive status of the concept of God (as a concept for which the usual distinctions between essence and existence do not hold), presupposing independent proof in the Third Meditation of the existence of God.

© Carleton B. Christensen, 2008, 2010, 2011, 2012, 2013and 2014

  1. Note that this is to say that while the proof of the existence of God provided in the Third Meditation resolves the epistemological issue of whether material things exist, indeed the very material things which show themselves to him in his perceptual experience, it does not resolve the ontological issue of what it is to be a material thing in that sense of the term “material thing” which is implicit in his perceptual experience. (This ontological issue has, of course, been touched upon in the discussion of the wax example at the end of the Second Meditation.)

  2. This shows that Descartes belongs to a long-standing tradition going back to Plato according to which the essence of an entity is what it truly is, and this is what makes it truly knowable, the object of systematic, and in particular unified theoretical description and explanation.

  3. That is, Descartes wants to assert as a general rule, that is to say, for all kinds of case in which it seems clearly and distinctly to him that p, and not just for that one, very special initial case in which it seems clearly and distinctly to him that he is as thinking, that if it seems clearly and distinctly to him that p, then he may rationally judge that p.

  4. And not just in the one, very special initial case of its seeming clearly and distinctly to him that p, namely, its seeming clearly and distinctly to him that he exists as thinking.

  5. Note that Descartes is in fact putting things inaccurately in at least one important respect: his conclusion should have been that necessarily all those things that he clearly and distinctly perceives are true. What he actually says entails that those empirical matters he clearly and distinctly perceives are necessarily true. But an empirical proposition such as that Canberra is the capital of Australia is clearly not necessarily true. This only underscores from another direction the point made in Lecture 6 that one must provide a fairly reconstructive account of Descartes’ doctrine of clear and distinct perception since his formulations of it are frequently very rough and imprecise.

  6. It would seem that the example of wax in Meditation Two does not embody or imply the knowability of material things in this strong sense. For the discussion of this example can really at most hope to show that the essential nature of a material thing such as a lump of wax lies hidden behind its surface sensible properties, i.e., consists in the often mathematically expressible laws which articulate how the non-sensible microstructure of material things determines these surface properties and how they succeed one another. And this surely does not entail that all of nature is governed by a single, unitary set of physical laws which could be captured in a single, unified theoretical account of nature. If so, then, in this conception of the essence and knowability of materials things, Descartes is in fact importing something into the notion of a material thing which is not inherent in his perceptual experience. In fact, what he is importing into his ontology of the material thing is the metaphysical interpretation of nature he provides in the Principia philosophiae. There, he provides what is in effect a decidedly metaphysical, indeed naturalist and physicalist account of nature into which he then has great trouble inserting human minds. It is important to note the essentially anti-Aristotelian, physicalist character of Descartes’ account of nature because so much of modern philosophy presents itself as naturalist, even physicalist and therefore anti-Cartesian. In fact, the difficulties contemporary naturalisms and physicalisms have with Cartesian dualism really constitute an internal family quarrel since their respective metaphysics of nature—the world minus minds, as it were—are, in general terms and character at least, the same.

  7. The suggestion that I do not so much learn as remember things already known is a tacit reference to Plato’s doctrine of anamnesis—see

  8. Caterus writes, “Even if it is granted that a supremely perfect being, by its very nature, implies existence, it still does not follow that such an existence is something that is actually present in the nature of things, but only that the concept of existence is inseparably linked with the concept of a supreme being. You cannot deduce from this that the existence of God is something actual, unless you presuppose that God is a supreme being who actually exists. If that were true, it would actually include all perfections, including the perfection of real existence.” As Georges Dicker points out, this objection was also made by the great Mediaeval theologian St. Thomas Aquinas in his Summa Theologica (part I, quest. 2, art. 1).

  9. As Descartes makes clear at the bottom of p.52, this issue of inherent vs. defined or acquired complexity of content has nothing to do with whether one does or does not learn the idea through experience. Perhaps indeed, Descartes says, “the idea of a triangle may have reached me through the sense organs, because I occasionally saw bodies with triangular shapes … .” (p.52) But this, he rightly observes, is beside the point. The point is rather that the idea, however one may have acquired it, is not an arbitrary construct or contingent composite of different elements.

  10. Which reflects the inherent complexity of the true and immutable natures they each express.

  11. On p.39, Descartes allows that “there are innumerable … things in God that I do not comprehend and which may be completely outside the scope of my thought.”