The Ontological Argument: Aquinas's Objection and Descartes' Reply PDF

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The Ontological Argument: Aquinas's Objection and Descartes' Reply by Blake D. Dutton At the heart of the Cartesian scientific revolution stands an episte- mological revolution directed primarily against the scholastic-Aristote- lians and their sense based epistemology. By repeatedly attacki...

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The Ontological Argument: Aquinas's Objection and Descartes' Reply by Blake D. Dutton

At the heart of the Cartesian scientific revolution stands an epistemological revolution directed primarily against the scholastic-Aristotelians and their sense based epistemology. By repeatedly attacking the reliability of sense-experience as a means of knowing the nature of bodies and their properties, Descartes sought to undermine scholastic accounts of nature and the substantial forms and real qualities invoked in those accounts. 1 Appeal to such forms and qualities was replaced in the Cartesian science with explanation in terms of the geometrical properties of matter and laws regulating the motion and interaction of bodies. This mode of explanation, vital for the establishment of a mechanistic physics, had its foundation in Descartes' new epistemology of clear and distinct ideas. The consequences of Descartes' revolution, however, extend beyond the realm of natural philosophy, for neither Cartesianism nor scholasticism was wholly directed to the knowledge ofthe material world. Both aimed in part at ｡｣ｱｵｩｲ ｾ natural knowledge of God though the exercise of the unaided intellect. Yet the epistemological frameworks in which Daniel Garber argues that Descartes' first target was the common sense conception of the world which attributes such tendencies (e.g., gravity and levity) and qualities (e.g., color and taste) to bodies as our senses ordinarily perceive them to have. Descartes, according to Garber, saw the scholastic philosophy of nature, with its substantial fonns and real qualities, in large measure as a systematization of this common sense conception of the world. If he could undennine the one, he could undermine the other. See Daniel Garber, "Semel in vita: The Scientific Background to Descartes' Meditations" in Essays on Descartes'Meditations, Amelie Oksenberg Rorty ed. (Berkeley: University of Califomia Press, 1986). 2 As early as 1630 Descartes wrote to Mersenne concerning the aim. of his metaphysics: "Perhaps I may some day complete a little treatise ofMetaphysics ... in which I set out principally to prove the existence of God and of our souls when they are separate from the body, from which their immortality folIows" 1

Copyright 1993, American Catholic Philosophical Quarterly, Vol. LXVII, No. 4

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each saw the acquisition of such knowledge as possible are decidedly different. One would, for example, be hard pressed to find a statement more opposed to the Cartesian spirit than the following from Aquinas's SUlnma Contra Gentiles: "According to its manner of knowing in the present life, the intellect depends on the sense for the origin of knowledge; and so those things that do not fall under the senses [e.g., God and the angels,] cannot be grasped by the human intellect except in so far as the knowledge of them is gathered from sensible things" (SCG I. 3. 3).3 We shall see that Descartes' entire approach to natural theology, based as it is on the clear and distinct perception of the nature of God, is irl direct conflict with this maxim. 4 This is perhaps nowhere more evident than in Descartes' fifth meditation argument for the existence of God-the so called "ontologieal" argument-which explicitly invokes SUChl clear and distinct perception of the divine nature. ｾｲ｡ｴｵｲ｡ｬ ｹＬ much debate sUITounded this argument in the seventeenth century. The followers of Thomas squared off against the Cartesians, charging Descartes with trying to resurreet an ｡ ｲ ｾ ･ ｮ ｴ which had already been thoroughly refuted centuries earlier. 5 Curiously, though, when Aquinas's criticisms of an Anselmian version of the argument were pointed out to Descartes by the theologian Caterus, he did not see (or pretended not to see) any discord between himself and Aquinas. 6 "On this issue," he writes, "I do not differ from the Angelic Ｈｌ･ｴ ｅｾｲ to Mersenne, 1630, AT I, 182). All citations from Descartes'writings are from Cottingham, Stoothoff, Murdoch, Kenny (trs.), The Philosophical Writings ofDescartes, 3 vols. (Cambridge: Cambridge University Press, 1984 & 1991). I will follow the Adam and Tannery pagination. 3 This, according to Aquinas, is true even of knowledge given through revelation which, though "it elevates us to know something of which we should otherwise be ignorant, ... does not elevate us to know in any other way than through sensible things." Aquinas, Expositio super librum Boethii De trinitate, Q. 6. A. 3. Thle text is taken from Aquinas, The Division and Methods of the Sciences, Armal1.d Maurer, trans. (Toronto: Pontifical Institute, 1986). Citations from this work v/ill hereafter be cited as In Lib. Boethii. de Trin. All citations from the Summ,a Contra Gentiles are from Aquinas, Summa Contra Gentiles, Book 1, Anton C. Pegis, trans. (London: University of Notre Dame Press, 1975). 4 Gary Hatfield argues that Descartes' claim to have a clear and distinct idea of God is actually employed as a counter-example to Aristotelian epistemology, in part, as an attempt to overthrow fundamental theses concerning the dependence of the intelligible species on a material image. See Gary Hatfield, "Reason, Nature, and God in Descartes," Essays on the Philosophy and Science of RenE? Descartes, Stephen Voss, ed., (Oxford: Oxford University Press, 1993), 264. 5 For an account of the controversy between Thomists and Cartesians concerning the ontological argument in the seventeenth and eighteenth centuries, see Alan Kors, Atheism in France, 1650-1729 (Princeton: Princeton University Press, 1990) ch. 9. 6 I use the term "Anseimian" because the argument which appears in Aquinas's text more or less corresponds to the argument given in the second chapter of the Proslogion. Neither Aquinas nor Descartes mention Anselm by name in

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Doctor in any respect" (AT VII, 82). This response is instructive, for Descartes clearly saw himself as forwarding an argument sufficiently different from the Anselmian argument to be immune from Aquinas's criticisms. His reply to Caterus, then, is invaluable for determining what, if anything, is the uniquely Cartesian nature of the fifth meditation argument. More importantly, the dispute with Caterus highlights key differences in the epistemological foundations of Descartes' and Aquinas's natural theologies, particularly conceming the origins of natural knowledge of God, the possibility of knowledge of the divine essence, and the self-evidence of the existence of God. In what follows I wish to explore these differences, beginning with an exposition of what I take Aquinas's criticisms of the argument to be. I will then turn to Descartes' response to these criticisms and argue that he indeed succeeds in formulating a unique version of the argument insofar as it proceeds from a consideration of the nature of God by way of a clear and distinct idea rather than from a consideration of the signification of the term "God." However, I will show that this does nothing to render the criticisms of Aquinas irrelevant. In fact, it actually serves to highlight those elements of Cartesian natural theology most opposed to Thomistic doctrine. Finally, I will close my discussion with some reflections on the relation of Descartes' argument to Aquinas's views on the beatific vision and argue that Cartesian natural theology describes a knowledge which Aquinas restriets to the supernatural state of beatitude. As such it can be read as a naturalized deseription of that state. I In discussing whether the existenee of God ean be known simply from a knowledge of the signifieation of the terms in the proposition "God exists," Aquinas examines a formulation of the ontologieal argument based on the second chapter of Anselm's Proslogion. 7 His formulation is as folIows: As soon as the signification of the word 'God' is understood,

it is at onee seen that God exists. For by this word is signified their discussions of the argument and it appears that Descartes may not have been directly influenced him. See Descartes' letter to ｍ･ｾｳ･ｮ ･ of 1640 (AT 111, 261) and a discussion of this issue in Etienne Gilson, Etudes sur le role de la pensee medievale dans la formation du systeme cartesien. (paris: J. Vrin, 1951),

215-33. In the Summa Theologica, Aquinas does not discuss the so called modal argument of the third chapter of Anselm's Proslogion. This argument is taken up in his Summa Contra Gentiles I, 10, 3 and I, 11, 4. I am ignoring this 'scussion because it does not come up in the dispute between Caterus and

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the thing than whieh nothing greater ean be eoneeived. But that whieh exists aetually and mentally is greater than that whieh exists only mentally. Therefore, sinee as soon as the word IGod' is understood it exists mentally, it also follows that it exists actually.8 In response, Aquinas points out that not everyone agrees that the signification of "God" is "a being than whieh none greater ean be ･ｯｮＨｾ･ｩｶ ､ＮＢ Even ifthis signifieation were aeeepted, however, it does not follow that one "understands that what the word signifies exists aetually, but only that it exists mentally" (ST I, 2, 1, ad 2). To understand the meaning of the name "God" is not to understand that God aetually exists outside the mind. Thus, Aquinas eoneludes, "it [cannot] be argued that [God] actually exists, unless it be admitted that there aetually exists something than whieh nothing greater ean be thought; and this preei.sely is not admitted by those who hold that God does not exist" (ST I, 2, 1, ad 2). Aquinas's reasoning here is obseure and brief. He seems to be argu-ing that the eonelusion "God aetually exists" fails to follow from the premisses of the argument unless the argument is made eireular by first positing the aetual existenee of God outside the mind. However, the aetual existenee of God outside the mind is preeisely what is under dispute. And beeause the opponent of the argument need not admit it as apremiss, the opponent remains free to deny it as a eonelusion. We find the same point in the Summa Contra Gentiles in which Aquinas discusses the argument in slightly greater detail: Now, from the fact that that whieh is indieated by the name IGod' is eoneeived by the mind, it does not follow that God exists save only in the intelleet. Henee, that than whieh a greater ･ ｾ ｯ ｴ be thought willlikewise not have to exist save only in the intelleet. From this it does not follow that there exists in reality something than whieh a greater eannot be thought. No diffieulty, eonsequently, befalls anyone who posits that God does not exist. For that something greater ean be thought than anything given in reality ... is a diffieulty 01UY to him who admits that there is something than whieh a greater eannot be thought in reality (BCG I, 11, 3). Here Aquinas is attaeking the key to the argument, viz., the inferenee from th.e signifieation of the name "God" to God's existenee. Clearly one ｄ･ｳ｣｡ｲ｢ｾｳＮ

STI, 2 2, 1, obj. 2. All citations from the Summa Theologica are from Aquinas, Summa Theologica, vol. 1. Dominican Fathers, trs. (New York: Benziger Brothers, 1948).

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of the burdens of the argument is to show that if the signification of the name "God" is "a being than which none greater can be conceived," then included in that signification is the condition of existing, not merely in the intellect, but in reality as weIl. This is done by treating actual existence as a condition for exceeding all other conceivable beings. But, Aquinas would argue, even if it is granted that actual existence is part of the very signification of the name "God," one cannot conclude from this that such a being actually exists. We can put the point as folIows. When the signification of the name "God" is understood, God is posited in the intellect as conceived or signified. Likewise, when one sees that the signification includes actual existence, actual existence is posited in the intellect as conceived or signified. But it is sheer confusion to argue from the fact that actual existence is posited in the intellect as part of the signification of "God" that we must posit the actual existence of God outside the intellect. Cajetan, the great sixteenth century commentator on Aquinas, elaborates: 9 It is conceded that the greater than all conceivable [Le., God] is signified and conceived with every perfection, even existence in the nature of things; in act, yet in signification. But an argument from signified and understood to being does not follow. And thus in the text it is said that for this reason nothing can be concluded. 10 The failure to see this, according to Cajetan, is due to a failure to distinguish between existence as signified (existentia ut significata) and existence as exercised (existentia ut exercita). The actual existence which is signified by the name "God" has being in the intellect. It is not to be confused with the exercised act ofexisting which belongs to a being posited outside the intellect. One cannot, Cajetan concludes, argue from actual existence as signified to actual existence as exercised. This distinction is invoked to solve the supposed difficulty of denying the existence of God on which the ontological argument rests. The argument is supposed to show that if one takes the signification of "God" to be "a being than which none greater can be conceived," then to conceive of God as not actually existing is not to conceive of God at all since actual existence is a condition of exceeding all other conceivable My use ofCajetan's commentary was suggested to me by my reading of J acques Maritain, Le Songe de Descartes. (paris: Buchet/Chasttel, 1932), 185-212. Maritain puts Cajetan's analysis to a different use than do I insofar as he assimilates the Carlesian and Anselmian arguments and employs Cajetan's analysis to refute them both. lOCajetan, Commentaria in Summam Theologiae, ed. Leonina Operum S. Thomae IV-XII (Romae, 1888-1906), In ST I, 2, 1. My translation.

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beings. Yet as Cajetan points out, this does not entail positing actual existence as exercised, for the conditions conceived by which a being would exceed all other conceivable beings need not be posited in reality and. outside the intellect in order for them to be conceived as conditions of e:x:ceeding. Once again, Cajetan elaborates: [To] exceed all which is conceivable occurs in two ways. One way, what exceeds in the nature of things [as exercised], another way according to conceived being [as signified]. And I contend, not that being in the nature ofthings, but objective [or conceived] being, is the reason of exceeding. 11 l'Tow the necessity ofmaking the argument circular in order to draw the eonclusion "God exists" is evident. God is conceived to be a being than which none greater can be conceived, and among the conditions conceived for exceeding all other conceivable beings is actual existence. This is understood when the signification of "God" is understood. But as we now see, we cannot infer from actual existence as signified to actual existence as exercised. Thus, to know the conditions of being a being than which none greater can be conceived is not to know that such a being exists, even if actual existence is conceived to be one of those condi:tions. The most we can know is that if there exists a being than whicll none greater can be conceived, because actual existence is a condition of being such a being, then such a being (Le., God) actually exists. But in order to affirm the consequent, we must first posit the ･ｸｩｳｴ ｾｮ｣･ of God. To quote Aquinas again, "it [cannot] be argued that [God] actually exists, unless it be admitted that there actually exists something than which nothing greater can be thought; and this precisely is not admitted by those who hold that God does not exist" (ST I, 2,1, ad 2).

11 Although Aquinas's objections are raised against Descartes by Catenls,12 Descartes does not meet these objections head on. Instead,

11 Ibid. 12Caterus himself adds that the only thing which follows from the fact "that a supremely prefect being carries the implication of existence in virtue of its very title ... is that the concept of existence is inseparably linked to the concept of a suprelne being" (AT VII, 99). - ------

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he emphasizes his agreement with Aquinas in dismissing the argument as Aquinas formulates it. So formulated, Descartes claims, the argument is manifestly invalid, for the only conclusion that should have been drawn is: 11lerefore, once we have understood the meaning ofthe word 'God' we understand that what is conveyed is that God exists in reality as weIl as in the understanding." Yet because a word conveys something, that thing is not therefore shown to be true (AT VII, 115). Descartes has no argument with Aquinas on the deficiency of the Anselmian formulation. But he goes on to claim that the argument as he formulates it is unique-so unique, in fact, that it does not suffer from these deficiencies and that any attempt to bring Aquinas's 'criticisms to bear upon it only signifies a misunderstanding of the argument and a misappropriation of Aquinas. This, he believes, is where Caterus has failed. What, we may now ask, is the basis of this claim and how does Descartes distinguish his argument from the Anselmian formulation which Aquinas rejects?13 Descartes' argument makes its first appearance in adumbrated form in the Discourse on Metlwd in 1637. There he simply notices that the 13Willis Doney has recently advanced a thesis apropos ofthis question which, if correct, would stop any further inquiry. He argues that Descartes was able to sidestep Aquinas's criticisms because there are in fact two versions of the argument in the fifth meditation. The target of Caterus's objections, he contends, is the second formulation of argument (Argument B) which moves from the recognition that existence is a perfection which must belong to a supremely perfect being to the conclusion that a supremely perfect being exists (see AT VII, 67-68). On Doney's scenario, when confronted with Caterus's objections, Descartes ignores this formulation of the argument and turns instead to a defense of an earlier formulation (Argument A). This version concludes that God exists from the fact that existence is clearly and distinctly conceived to belong to the divine nature coupled with the fact that whatever we clearly and distinctly conceive to belong to the nature of a thing can truly be asserted of that thing (see AT VII, 65-66). It is no surprise, Doney maintains, that Descartes would charge Caterus with misunderstanding his argument, for he would naturally not see objections directed against Argument B as having any bearing upon Argument A. Of course this charge can only be maintained by ignoring the presence of Argument B in the fifth meditation. Thus, Doney concludes, "where both Caterus and Descartes go wrong is in implying that an argument like A· or B* is the only argument to be found there [in the fifth meditation]." Willis Doney, "Did Caterus Misunderstand Descartes' Ontological Proof?" in Voss, Essays, 81. It is clear from all ofthis that Doney sees no genuine controversy here. Like two ships passing in the night, Caterus and Descartes never engage one another directly and the entire exchange falls short ofgenuine dialogue. Yet even ifwe grant Doney's two argument thesis and his analysis of who attacks and defends what (itself extremely problematic), it will become clear as we examine Descartes' response that there is not only genuine controversy here, but that Aquinas's criticisms bear most strongly on Argument

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idea of existenee is evidently ineluded in his idea of a perfeet being. He eoncludes directly from this that "it is at least as certain as any geometrieal proof that God, who is this perfeet being, is o...