Descartes' Ontological Argument

David Banach



This paper is an examination of Descartes' ontological argument, the traditional and modern criticisms of the argument, and some of the contemporary commentary on ontological type arguments. I will first look at the ontological argument as it is presented in Descartes' major works, and then form an interpretation of the argument in its final form. The emphasis in interpretation will be on the attempt to find the most plausible and interesting argument among the varying expressions which Descartes gives to the ontological argument.

I will then look at and try to evaluate some of the criticisms that seem to be relevant to Descartes' argument. Criticisms offered by Descartes' contemporaries, as well as those offered by modern and contemporary philosophers, will be examined. Throughout the paper, I will not limit myself to those sources which directly refer to Descartes: I will also 1ook at those criticisms of other statements of the argument that seem to be relevant. I will conclude by attempting to make an overall evaluation of the argument in light of the considerations discussed. My main thesis is that the inclusion of the notion of necessary existence, as introduced by Descartes in the later statements of the argument, gives the argument a certain plausibility that, while being far from totally convincing, establishes a definite price for the rejection of its conclusion.


Part II: The Argument

The ontological argument receives its major expression from Descartes in Meditation V.

... from the very fact that I can derive from my thoughts the idea of something, it follows that all that I clearly and distinctly recognize as characteristic of this thing does in reality characterize it ... It is certain that I find in my mind the idea of God, of a supremely perfect being... and I recognize that an actual and  I eternal existence belongs to his nature ....1

After considering the objection that there is a distinction between existence and essence, that one could attribute existence to the nature of God even though no God existed, Descartes offers these further qualifications of the argument:

From the fact alone that I cannot conceive of God except  as existing, it follows that existence is inseparable from him, and consequently that he does, in truth, exist. Not that my thought can bring about this result or that it imposes any necessity upon things: on the contrary, the necessity which is in the thing itself -— that is, the necessity of the existence of God—-determines me to have this thought. For it is not. in my power to conceive of a God without existence——that is to say, of a supremely perfect Being without a supreme perfection ... 2

In the logical development of the Meditations, the ontological argument is an extraneous consideration, brought in during a dis­cussion of the essences of material things after the existence of God had already been proven in the third Meditation, in the Principles of Philosophy and in the arguments drawn up in geometrical order given in the replies to the objections the argument is given a much more prominent position. It is also in these expressions of the argument that the notion of necessary existence receives its fullest exposition.

As can be seen from the following passages, Descartes makes it clear that he is referring to a special kind of existence, necessary and eternal existence:

When mind ... discovers the idea of a Being who is omniscient, omnipotent and absolutely perfect ... in it it recognizes not merely a possible and contingent existence, as in all other ideas it has of things, ... but one that is absolutely necessary and eternal. ... from the fact that it perceives that necessary and eternal existence is comprised in the idea it has of an absolutely perfect being, it has clearly to conclude that this absolutely perfect being exists.4

But if I think that existence is contained in the idea of a body of highest perfection, because it is a greater perfection to exist in reality as well as in the mind than to exist in intellect alone, I cannot conclude that this utterly perfect body exists, but merely that it may exist. ... when I examine this idea of body I see in it no force by means of which it may produce or preserve itself, I rightly conclude that necessary existence, which alone here is in question does not belong to the nature of a body .... But yet if we consider whether existence is congruous with a being of the highest perfection and what sort of existence is so, we shall be able to clearly and distinctly perceive in the first place that possible existence is at least predicable of it, as it is of all other things of which we have a distinct idea.... Further, because we cannot think of God's existence as ,   being possible , without at the same time ... acknowledging that He can exist by His own might, we hence conclude that He really exists and has existed from all eternity....5

Existence is contained in the idea or concept of everything, because we can conceive of nothing except as existent, with this difference, that possible or contingent existence is contained in the concept of a limited thing, but necessary and perfect existence in the concept of a supremely perfect being. ... To say something is contained in the nature or concept of anything is the same as to say that it is true of that thing. But necessary existence is contained in the concept of God. Hence it is true to affirm of God that necessary existence exists in him, or that God himself exists. 6


I have quoted from these passages at considerable length in order to show that Descartes unequivocally offers an argument that differs considerably from traditional interpretations of the ontological argument. The archetype for most of these traditional interpretations is the ontological argument given by St. Anselm in Proslogium II. Descartes argument, as interpreted traditionally is something like this: I have an idea of God as a supremely perfect being. Existence is a perfection. God must exist in reality or else the supremely perfect being would lack a perfection, and this is absurd. God's essence or nature contains existence just as the essence of a triangle contains it having three sides. The emphasis in these types of interpretations is on the use of existence as a predicate and a perfection which one must attribute to the nature of the supremely perfect being. Philosophers who have made this type of interpretation of Descartes ontological argument are Bertrand Russell7, Bernard Williams8, Norman Kemp Smith9, and John Hick10, to name just a few.

While this interpretation fits the first passage quoted from the Meditations above (p. 2) and makes for an easy identification of Descartes argument with that of Anselm, it does not fit the second passage from the Meditations quoted above and is in open contradiction to much of what is said in the Principles and the replies to the objections. In the reply to the first objection quoted above(p. 3) Descartes openly rejects this type of interpretation.11  Any interpretation that pretends to adequacy must do justice to the clearness and directness with which Descartes

declares that he is dealing with necessary existence as part of the perfection of God, not simply existence, which he admits is part of the essence of anything conceivable. When one looks at the latter part of Meditation V in this light, and when one sees Descartes' remark after one of the clearest of his expositions of the argument in the replies, ("All this ... differs from what I have already written only in the method of explanation adopted"12) it is clear that it will not do to maintain there are two separate arguments in: the Meditations and in the replies.

I shall try to give an interpretation of the argument that is in accord with both the text and general scheme of the Meditations as well as the replies to the objections and the Principles. From his discussion of essences in the beginning of Meditation V, Descartes concludes that all that one clearly and distinctly perceives as characteristic of the essence of a thing does actually characterize it.13   To say that something is contained in the essence of anything is to say that it is true of that thing.14 I have an idea of God as a supremely perfect being. Upon reflection, I find that the essence of a supremely perfect being must contain necessary and eternal existence.15  I cannot conceive of God as not existing; this is not because my thought imposes the necessity, but because eternal and unconditioned existence is required by God's nature as omnipotent and perfect. My idea of God insofar as it is adequate or clear and distinct must reflect this necessity.16  The essence of God contains necessary existence: God exists. In the special case of perfection, my idea must have objective reality due to the character of what it represents.

A few comments are in order before moving on to a consideration of the criticisms of the argument. It is clear that what Descartes means by necessary existence here is not what modern philosophers call logical necessity. Descartes is dealing with ontological necessity or eternal and unconditioned existence. He brings in considerations of epistemological and psychological necessity because on his epistemology, these considerations enable us to know with certainty about ontological considerations. A great many of the criticisms of the argument are aimed at this epistemology rather than the argument itself. The two are not necessarily interdependent.

The distinction between contingent and necessary properties for Descartes is very important. He almost always is referring to either contingent or necessary existence rather than simply to plain existence as is most commonly supposed. For example, when Descartes says, "... we can conceive nothing except as existent." he means that contingent or possible existence is contained in the essence of everything that is not contradictory, not actual existence. In plainer language, everything that is coherently conceivable is a possible actual-existent. God is a necessary actual-existent. This will be dealt with more fully in the next section.



I shall discuss three major areas in which most of the criticism of Descartes' ontological argument has fallen. The first of these areas is the controversy over existence and predication, especially in the case of perfection. I will then consider the problems of bridging the gap between ideas and things and of forming a conception of God that is clear and distinct as well as coherent.


The problem of existence and predication is first brought up in the fifth set of objections by Gassendi. He says, "Next we must note that you place existence among the Divine perfections, without, however, putting it among the perfections of a triangle or a mountain, though in exactly similar fashion, and in its own way, it may be said to be a perfection of each. But... existence is neither a perfection in God nor in anything else; it is rather that in absence of which there is no perfection."18   Gassendi is

maintaining that existence is not a property or predicate, the possession of which makes something better than a thing which lacks it. David Hume makes a similar point in his Treatise: "To reflect on any thing simply, and to reflect on it as existent, are nothing different from each other. That idea, when conjoined with the idea of any object, makes no addition to it. Whatever we conceive we conceive to be existent."19  Kant's is the most famous of the

criticisms along this line. He holds that existence is not a real predicate because it adds nothing to the concept of which it is predicated. Kant also holds, as Hume does, that no denial of an existential proposition can be self-contradictory. Bertrand Russell reinforces both of these points with his theory of descriptions.


In this theory, the logical structure of existential statements is interpreted in this way: "the B exists" means "there is one and only one x such that x is a B." On this analysis it is clear that existence is not a predicate that adds anything to the defining properties of a class.

While this class of criticisms is most often represented in the criticisms of modern philosophers it is the least relevant to Descartes formulation of the ontological argument. As should be apparent from the passages cited, Descartes is dealing with ontologically necessary existence. Hume's criticism that whatever the mind clearly conceives includes the idea of possible existence20 and Kant's criticism that existence adds nothing to the concept of which it is predicated were both anticipated by Descartes when he says, "Existence is contained in the idea or concept of everything, because we can conceive nothing except as existent."21 Here he is speaking of contingent existence. If a concept is not self-contradictory then it represents a possible existent. If Descartes' argument in any way requires that existence be a predicate, it is a universal predicate of all concepts, therefore we could not expect it to add to the concept of anything. More importantly, Descartes is dealing in the argument with necessary existence:

it is clear that to predicate of something the ability to exist of its own might eternally22 does add something to a concept.

Nevertheless, I will offer some short criticisms of Kant's attack on existence as a predicate. William Alston offers the criticism that while existence in general is a universal predicate and can add nothing to a subject, particular modes of existence such as in intellectu or in posse can add something to a subject

in a different mode of existence from that being predicated.23 Jerome Schaffer holds that due to a narrow account of predication. Kant's view makes it impossible for any predication at all. If predication is adding to and revising the subject, then in the act of predicating the subject changes and the proposition says nothing about the original object of the conception.24  This contention, however, seems to be based on a too narrow conception of what Kant means by a predicate adding to a subject. The criticism
offered by both Hume and Kant, as well as Russell, leads us into
the next class of criticisms, that of the problem of bridging
gap between concepts and things. All of these philosophers hold
that matters of fact cannot be arrived at by a mere consideration
of ideas.

Other representatives of this class of criticism are Caterus, who holds that the conclusion of the argument should be that the essence of perfection contains existence, not that this existence is anything actual in the real world.25  John Hick, who holds that all forms of the argument similar to Descartes', as interpreted above, contain an illicit jump from logical necessity to ontological necessity26; J.N. Findlay, who holds

that it is impossible to pass from abstract reasonings to concrete existence27; Jerome Schaffer, who holds that the argument proves only that its intensional object, God, must have the predicate of existence, but not that this concept has extension, that God exists28; and all of modern logic, which holds that existential propositions are hypothetical, like all other subject-predicate propositions.


All these diverse sounding criticisms say essentially the same thing, with the possible exception of Findlay. They all say that one cannot derive a proof for the existence of God, from a consideration of concepts, and that, therefore, the correct conclusion of the ontological argument is that whenever we think of God we must think of Her as necessarily existent. Descartes reply would most likely be that when we know that a certain characteristic belongs to the essence or nature of something in most normal cases, all we know is that the characteristic belongs to the thing as a possible existent. That is , if it exists then what we have clearly and distinctly perceived as belonging to the nature of a thing, will belong to it* in most normal cases the essence of a thing contains only contingent or possible existence. In the case of God, a perfect being, where the concept must include necessary existence, then according to our axiom that whatever we clearly and distantly perceive as belonging to the nature of a thing really does belong to that thing, in the special case of God we can derive his existence from his nature. Both this reply and most of the criticisms beg the central question, namely, whether or not we can discover matters of fact by considering ideas: that is, whether the characteristics we clearly and distinctly perceive as belonging to the idea of a thing actually belong to a thing. Among modern philosophers the answer to this question is almost always no and is always given with an air of certainty despite its obvious contradiction of common sense. The obvious contradiction lies in holding that we can learn nothing from a consideration of mere ideas when in fact most of our knowledge of matters of fact is gained from a


consideration of mere ideas which are about matters of fact. Our theoretic knowledge of science as exemplified in Quantum and rel­ativity theory are examples. To hold that all the knowledge we have gained from these theories comes from a consideration of the photoelectric effect and black box radiation phenomena from which these theories gained their initial empirical basis seems ludicrous. More relevant, however, are some examples of existential statements that seem to tell us of matters of fact while being at the same time necessary relations between ideas.  For example, "Something exists." and "There does not exist an entity which can be both blue and red in respect to the same extension at the same time." are both existential statements whose denials are self-contradictory. A Cartesian analysis of these statements would be similar to this: In the first case, the essence or idea of something would be seen to contain necessary existence in a manner similar to the idea of God. In cases like these there is a necessity in very abstract characteristics of the world, not a logical necessity but an ontological one. Descartes would say, as he does in Meditation V, that clear and distinct ideas will reflect this necessity: that is, we will be unable to conceive of the denial of these propositions. The position that there is no guarantee that a logical necessity will reflect an ontological necessity seems to deny the possibility of knowledge. At any rate, given the previous Meditations  and their conclusions , Descartes can easily avoid this problem: in fact, it seems that the entire purpose of the Meditations is to resolve this problem. While most of Descartes critics would not accept the earlier conclusions


of the Meditations, Descartes should not be too disappointed if he cannot convince those philosophers who hold that we can have no certain knowledge at all of God's existence. The denial of Descartes' argument on these grounds has some strange implications. If one is to hold that logical necessity need not reflect ontological necessity in the things that the ideas are used to refer to, then he must hold such logical oddities as: "Nothing exists is a possible state of affairs" and " It is possible to have ones cake and eat it too."

J.N. Findlay along with the author of the second set of objections are the main representatives of the third class of criticisms. These critics bring up the difficulties in maintaining that one has  a coherent conception of God. Caterus also states a form of this criticism in the first set of objections and this statement is a simpler form of the objection. Caterus says that Descartes cannot be sure that God exists because he cannot know if God's essence is a true and immutable essence or simply a fiction of our own making.29

In the context of the Meditations this would have been answered by the third Meditation. As an independent argument, the ontological argument has considerable trouble with this objection in its varying forms. Descartes answers Caterus by maintaining that if the idea of God were a fiction, a product of synthesis, we would be able to analyze it into its components as we can the idea of a unicorn.30  With the more serious objection that we

cannot know if the idea of God is a coherent idea at all, Descartes has more serious problems. This criticism is first offered by


the author of the second set of objections. He holds that it does not follow from the argument that God exists, but only that He ought to exist if his nature were anything possible or non-contradictory.31  J.N. Findlay offers a similar argument in a more modern setting. He holds that what the argument requires is a logically necessary existent, and that since a logically necessary existent is impossible, the argument constitutes a disproof of God's existence.32

Findlay's criticism seems to rest on the mistaken assumption that God's existence is proven to be logically necessary by the ontological argument. Descartes makes it clear that he is dealing with ontological necessity.  In reply to the second objection, Descartes maintains that because we see clearly and distinctly all that should belong to our concept of God and that this concept has no contradictions.33   This, however, brings up the question of whether Descartes' God can be the God of religion then. Charles Hartshorne has pointed out that the traditional religious conception of God as absolute perfection that nonetheless is able to act and change is incoherent. If something is absolutely perfect, any change must be a retrogression: and any retrogression is incompatible with absolute perfection. If we are to take his claims of having a clear and distinct coherent idea of God, then this idea must have been quite different from the traditional religious conceptions of God.

It seems to me that Descartes can meet the criticisms of the first two classes of critics when armed with the distinction between contingent and necessary existence and the notion of


ontological necessity. It seems highly improbable that an argument such as the ontological argument can ever demonstrate with a reasonable degree of certainty that we have clear and distinct ideas of God and that these ideas are coherent. But more importantly, it seems extremely difficult to ascertain that a conception of God represents something ontologically

possible, and this is required for proof. If an idea refers to something that is not even possible, it is really meaningless.35

Descartes' argument does not establish this, but it does establish a price for rationally affirming the non-existence of God; this price is the admission that the God concept is an empty one.



1 Rene Descartes, Meditations, Trans. Laurence J. Lafleur (Indianapolis: Bobbs-Merrill, 1960) p. 62.

2 Ibid., pp. 63-64.

3 Rene Descartes, The Essential Descartes, ed. by Margaret D. Wilson (New York: New American Library, 1969) p. 313principle No. 14 and Rene Descartes, Philosophical Works of Descartes.II, Trans, Elizabeth S. Haldane. and G. R. T. Ross (Dover, 1955) p. 57.

4 Haldane and Ross, op. cit. p. 21.

5.Ibid. p.21.

6 Ibid. p.57.

7 Bertrand Russell, A History of Western Philosophy, (New York: Simon and Schuster, 1945) P. 417.

8 Bernard Williams, "Descartes, Rene." (Encyclopedia of Philosophy, 1972 ed.) p. 350.

9 Norman Kemp Smith, New Studies in the Philosophy of Descartes,(New York: Russell, 1963) pp. 305-307.

10 John Hick and C. McGill, The Many-faced Argument, (Philosophical Review, 1960) pp. 210-211.

11 Haldane. and Ross, pp. cit., p. 21.

12 Ibid., p. 22.

13 Lafleur, op. cit., p. 62.

14 Haldane and Ross, op. cit., p. 57.

15 Ibid., p. 186.

16 Lafleur, op. cit., p. 64 and Haldane and Ross p. 21.

17 Haldane and Ross, op. cit., p. 57.

18 Ibid., p. 186.


19 David Hume, A Treaties of Human Nature, ed. by L.A.Selby-Biggs (Oxford, 1888), p. 66.

20 Ibid., p. 32.

21 Haldane and Ross, p. 57.

22 Ibid., p. 21.

23 R.M. Alston, "The Ontological Argument Revisited,"(Philosophical Review, 69, 1960) pp. 452-474.

24 Jerome Schaffer, "Existence, Predication, and the Ontological Argument", in John Hick, The Many-Faced Argument, (New York:1967)pp. 226-245.

25 Haldane and Rosa, p. 7.

26 Hick, op cit., p. 353.

27 J.N. Findley, Language, Mind, and Value.

28 Schaffer, op. cit.

29 Haldane and Ross, p. 8.

30 Ibid., p. 20.

31 Ibid., p. 28.

32 Findlay, op. cit.

33 Haldane and Ross, p. 45.

34 Charles Hartshorne, The Logic of Perfection. (Open Court 1965)Chap. 1.

35 Hartshorne, Mans Vision of God, p. 304.




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