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Spinoza & Leibniz on the Nature of God

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In his Ethics, Spinoza argues that substance is that which is independent of all contingent properties or accidental attributes. As something that neither comes into being nor passes out of existence, substance is something that necessarily is, and must be independent of necessity.

According to Spinoza’s account of substance, “thought” and “extension” are two fundamental properties, or qualities of substance. Spinoza extends his account of the nature of substance to the question of the nature of God, inquiring as to whether God, as an incorporeal entity, can create material things. According to the division of substances into two types, thought and extension, Spinoza maintains that no two substances can possess the same nature or attribute, or they would necessarily be the same thing. Nor, Spinoza adds, can one substance be the cause of another, for there again, the substance causing and the substance caused would be identical.

Thus, Spinoza argues that substance must be self-caused because existence, by definition, belongs to the nature of substance. The properties of being “eternal” and “infinite” also belong to the nature of substance, as the existence of substance is contingent upon nothing other than itself. If substance were finite, then it must be caused; but this is not the case, so substance must be a single infinite thing. According to Spinoza, the more reality a thing has, the more attributes it has; hence, substance, being a single thing, must possess all infinite attributes.

If it is granted that substance is simple, eternal, and infinite, then it follows that there is no other substance but God. As the only substance, God possesses all attributes infinitely and eternally. Accordingly, from the necessity of the divine nature, there must come an infinite number of attributes, expressed in an infinite number of ways. As there are only two types of substance— thought and extension— then it follows that everything that is possible is actual and necessary.

God, according to Spinoza, is the efficient cause of all things per se, or through Himself, rather than per accidens, or through secondary causes. God is free in the ultimate sense, constrained under no force external to Himself. Human beings, on the other hand, do not possess the same freedom as God, but only believe ourselves to be free agents and the executers of our actions. Because God is the only free being, human beings are necessarily determined beings. As there is no substance but God, it follows that there is no mode of the single substance that determines itself. According to the rule of sufficient reason, a thing determined by God cannot be otherwise, or it would not be possible; and a thing could not be possible if it were not otherwise.

In his Discourse, Leibniz takes issue with the fact that Spinoza denies God a moral nature. According to Spinoza, human beings are not free to choose, and are therefore not possessors of a moral nature. By the same token, God, as the determiner of all things possible, and manifestation of all things actual, is the only free being as such; but God’s freedom is not such that some choice is involved in what is actualized, since there is nothing which is not possible which is not actual.

For example, goodness, as an attribute of the nature of God, would only serve to restrict the infinite power of God, which is not possible, since there is no other substance but God, and thus no delimitation in the nature of God whatever. According to Leibniz, God is infinite and is lacking no possible perfection. However, Leibniz maintains that “Goodness” is perfection, and so to deny this attribute to God’s nature would be to somehow place a limitation on God’s perfection. Things are not good because God loves them, but because they are good in themselves, and thus perfect in terms of God’s infinite creative power. It is necessary for Leibniz to show that the world that exists is the best of all possible worlds— or that the world that exists lacks no possible perfections.

Like Spinoza’s God, which is pure intellect, Leibniz maintains that the best possible world is created of intellects, or finite substances (monads). As a purely intellectual being, God cannot create anything but intellects; hence, the creation, under Leibniz’s system, of an infinity of minds begets an infinity of perspectives. “Minds,” according to Leibniz, means anything constituted with the faculty of perception, and everything that God creates, perceives. The physical world is therefore a vast perceiver of sorts that is harmonized together in its respective perceptions. Discord of perceptions amongst what God creates would not be in accordance with his infinite perfection, and thus all harmonized perceptions beget in turn the observable uniformity in the laws of nature.

Because God, using the fewest number of principles, creates the infinite of perspectives in nature, and the world that God creates is the best of all possible worlds, monads, being substances, never come or go out of existence, and are each unto themselves like a complete world. Like an infinity of mirrors of God, each monad reflects the entire universe from its particular perspective. As we observed, God has made the best of all possible worlds, and accordingly, God wills the most good possible. Leibniz overturns Spinoza’s amoral universe by noticing that any being possessed of a rational intellectual nature must, like God, have a free nature, and this means that every creature with a rational intellectual must be a freely choosing moral being.

It is logically impossible to bring about the greatest good without freely choosing moral beings, and thus Leibniz introduces his conception of theodicy to account for the existence of evil in the world. If every event and action were determined by God, anything He creates, whether possessed of an intellectual nature or not, would be a kind of puppet rather than a free agent. Because God, in order to bring about the maximal good in the best of all possible worlds, creates beings that are free moral agents, absolves Himself of responsibility for the evil that exists in the world. Leibniz notes, however, that even what appears to be evil is actually, in the end, turned to good, and is thus an evil necessary to bring about the maximal good in the created world.

The Question Of The Immortality Of The Soul In Descartes’ Epistle To The Sorbonne

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I. The Question of Immortality

In his Dedicatory Letter to the Sorbonne, Descartes presents his Meditations to the Dean and Doctors as a work of Christian apologetics, while suppressing his incendiary goal of demolishing the entire Aristotelian metaphysics, physics, and psychology with the critical principle of rationem dubitandi. Descartes’ methodological doubt functions as a general principle for critiquing what Aristotle and his Scholastic followers took for granted — the reliability of the rational soul’s knowledge of the material world gained through the senses.1 The Aristotelian-Scholastic’s proofs for the soul typically began with some form of evidence derived from the order of corporeal being, such as the fact that living things possess the power of self movement and growth, then causally deduced the formal principle from the material principle — for example, living things that move and grow and reproduce are animated by soul. However, concerning the survival of the incorporeal soul after the dissolution of the body, Aristotle does not give a consistent opinion, except on the point that the rational soul is “capable of existence [i.e., functioning] in isolation from all other psychic powers.”2

The demonstrable fact that the rational soul engages in operations such as calculation, speculation and contemplation, in which the body has no share, is not tantamount to the Thomistic claim that the soul has an existence — not merely an operation — entirely independent of the body that it is the form or actuality of. In his Summa Contra Gentiles, Thomas maintains, contra the view of Aristotle, that if the human intellectual soul, which is the actuality of the human body, possesses operations that are in no way dependent on the body’s operations, 3 then it follows that the intellectual soul is capable of continuing its operation of intellectual apprehension (intelligere corrumpitur) after the death of the body.

Descartes maintained that such proofs were not conclusive because man’s knowledge of the ontological order was made to depend on the perception of the fallible senses as the first principle of knowledge. For Descartes, the necessity for providing indisputable proofs for the existence of God and the separability of the soul from the body was of particular importance,4 considering that the dubitability of the evidence obtained through the senses, and the hypothesis of the malin génie, called into question the validity of any proof that presupposed the reliability of the senses, such as Thomas’ proofs for the existence of God and the immortality of the soul. By calling his addressee’s attention to the point that his project for proving the existence of God, and that the soul does not perish with the body, corresponded to the traditional Scholastic enterprise, Descartes sought to align his proofs with the long-accepted attempts of his Scholastic predecessors.

Citing the Lateran Council held under Pope Leo X in session eight, Descartes attempted to further legitimize his philosophical investigation into the nature and immortality of the soul by supporting his quest for epistemological certainty with Leo X’s mandate for Christian philosophers to refute the arguments of irreligious philosophers who hold “that the soul dies along with the body.”5 Be that as it may, Descartes’ mission as a philosophical apologist for the truth of Christian doctrine involved more than simply upholding the tenets of the Faith with rational arguments, as there was nothing innovative or new in doing so.

The sense that Aristotelian philosophy was a stagnant body of knowledge was part of the impetus behind Descartes’ desire to look afresh at the foundations of philosophy. That the Church had, in making Aquinas its representative theologian, implicitly “Christianized” the thought of Thomas’ master, Aristotle, was an alliance that made the doctrines of Christianity dependent in crucial ways on the philosophic principles and reasoning of a pagan philosopher.6 Hence, Descartes hoped to free Christian philosophy from the influence of, and dependence on Aristotelian philosophy, while setting the traditional questions of natural theology on a philosophically indubitable and Christian foundation.

When he broaches the question of the nature of the soul, Descartes could have had nothing other than the opening of Aristotle’s De anima in mind, writing, “As regards the soul, many people have considered that it is not easy to discover [non facile investigari] its nature…”7 Aristotle’s procedure for inquiring about the soul in De anima begins with what is perceptible or intelligible, and moves to the underlying principle or mechanism: “…in the order of investigation the question of what an agent does [movement] precedes the question, what enables it [i.e., the soul] to do what it does.”8 Aristotle does not begin his inquiry into the nature of the soul with thinking, since thought itself is neither perceptible, nor is it an intelligible species that takes itself as its own object; that is, Aristotle’s account of the rational soul does not begin with a demonstration of rationality.9 Descartes reverses Aristotle’s procedure for inquiring into the nature of the soul, and begins his Meditations by inquiring into a type of purely rational mental activity that is comparable to Aristotle’s conception of theoria, or contemplation, and then moves, in the Sixth Meditation, to where Aristotle’s investigation begins, which is an account of the perceptible activity of the agent that the soul/mind informs.

II. From Immortality to Separability

In his letter to the Dean and Doctors of the Sorbonne, Descartes claims that the existence of God and the immortality of the soul “are prime examples of subjects where demonstrative proofs ought to be given with the aid of philosophy rather than theology;” and further, “that the only reason why many irreligious people are unwilling to believe that God exists and that the human mind is distinct from the body [mentemque humanam a corpore distingui] is the alleged fact that no one has hitherto been able to demonstrate these points.” That no prior proof for the existence of God and the immortality of the soul is immune to contradiction or refutation is precisely what Descartes is claiming to be the case, bluntly stating that, “I would add that these proofs are of such a kind that I reckon they leave no room for the possibility that the human mind will ever discover better ones.”10

However, a rational proof for the existence of God and the immortality of the soul would invalidate the necessity for God’s participation in revealing Himself to man, and the soul’s salvation would not require God’s intervention any more than its survival after the death of the body. Aquinas was particularly aware of the religious or fideistic dimension to the question of the soul’s immortality. If the self-subsistence of the soul could be conclusively demonstrated, then God’s act of preserving the soul after the body dies would become superfluous, since the soul would be inevitably immortal, and without any need of divine support.11

Prior to addressing the matter of the nature and immortality of the soul in his letter, Descartes draws on Biblical passages that declare man’s knowledge of the existence of God to be “manifest” in order to build a case for the proof for the existence of God given in the Meditations. As Descartes’ proof for the separability of the soul from the body in the Second Meditation hinges dialectically on his proof for the existence of God as an innate idea of the mind, the soul is conceived of as tantamount to mind.12 The conflation of soul with mind leads Descartes to allude in his Sorbonne letter to his doctrine of innate ideas, writing that “everything that may be known of God” through the Scriptures, including man’s knowledge of God’s existence, “…can be demonstrated by reasoning which has no other source than our own mind.”13

Descartes’ phrase, “no other source than our own mind,” introduces a subtle shift in the argument, and is intended to transfer man’s knowledge of the existence of God from the sensible effects wherein God’s existence is evident throughout His creation, to a knowledge of God’s existence that is neither discursive, nor requires any recourse to the theological Biblical tradition. Knowledge of the existence of God derived from His sensible effects is, according to Descartes, a fallacy in the order of knowledge; the corporeal organs of sense only sense what is sensible, and God, who is incorporeal, cannot be apprehended in His existence through the corporeal senses. The dubitability of sensible objects and their effects undermines the validity of knowledge derived from the material world; hence, if man’s knowledge of the existence of God is drawn from sensible effects, then the existence of God can be called into doubt through the same channels by which His existence was asserted.

On the other hand, in the Third Meditation, the necessity of the mind’s a priori knowledge of the existence of God is deduced from the infinite nature of God, as there is no other means by which a finite mind could be in possession of the idea of an infinite being.14 Further, Descartes maintains that,

the mere fact that God created me is a very strong basis for believing that I am somehow made in his image and likeness, and that I perceive that likeness, which includes the idea of God, by the same faculty which enables me to perceive myself.15

The thesis that the mind is made in God’s image and likeness rests upon the assumption that the mind possesses judgment, rationality, and will — in other words, those communicable attributes that God possesses infinitely and perfectly, and the human mind, to a limited and finite degree. Because the meditator perceives both God and the ego through the same faculty, i.e., the understanding, what is predicated of God — infinity and perfection,16 is also predicated of the mind, but to a diminished degree of perfection.17 The quasi-univocity between the innate contents of the mind and the mind’s simultaneous apprehension of the knowledge of the existence of God and the ego confirms that the mind has natural knowledge of God in the same way that the mind perceives itself — the force of the intuition that to think (i.e., to act), one must exist, impresses itself on the understanding with the same indubitable force as the fact that if a finite mind has an idea of an infinite, perfect being, it follows that an infinite perfect being must perforce exist.

The Sorbonne faculty, as Descartes was well aware, were Aristotelian-Thomists, and held that the first principle of man’s knowledge was the grasping of concrete existence in its singularity, which apprehension depended upon the sensible object received by the active intellect via the phantasm. Without the sensible object, neither the active nor the possible intellect could be activated, and the intellect’s abstraction from the particular thing to grasp the intelligible species could never take place. Man’s knowledge of the existence of God, deriving from the order of created things, points to the necessity of His existence as the first cause of the material world, and the requirement that there exist in the universe intellectual creatures that bear “a likeness to its source, according to its being and its nature, wherein it enjoys a certain perfection.”18

Man’s rational soul, or intellectual nature, cognizes the existence of God by the rational faculty that has its basis in the priority of the sensible object given to the active intellect through the phantasm. Descartes’ emphasis on the ease with which the existence of God is thinkable subordinates the chain of causes in the sensible order to the chain of causes in the order of ideas. That the existence of God, according to Descartes, is more self-evident than the existence of the sensible world, alters the Aristotelian/Thomist conception of the intellectual soul, which apprehends its object via the simple class of objects that Aquinas refers to as “sensible by accident,” or objects which are intelligible in themselves.19 However, Descartes wished to gain the commendation of the Sorbonne for his Meditations, and to do so required a subtle method of aligning his ostensibly anti-Aristotelian conception of God and the human soul with the views upheld by the staunchly traditional Sorbonne faculty:20

I have noticed both that you and all other theologians assert that the existence of God is capable of proof by natural reason, and also that the inference from Holy Scripture is that the knowledge [cognitionem] of God is easier to acquire than the knowledge we have of many created things…”21

In this rhetorical gesture, Descartes first presents his conception of man’s knowledge of God’s existence as an innate idea of the mind, which is a pivotal move in his attempt to persuade the theologians that his metaphysics does not diverge from the main topics of prior systems, but serves to reckon together and codify all “arguments that have been put forward on these issues by the great men,” whose arguments Descartes praises as having “the force of demonstrations.”22

In his letter, Descartes strategically combines established doctrines of the Church with the traditional Scholastic endeavor to generate proofs for the existence of God and the immortality of the soul, and then, in the Meditations, ingeniously modifies the purpose of speculative philosophy and natural theology to support the practical ends of physical science. It is noteworthy that the Sorbonne letter only contains one passing mention of science, when the wider purpose of the Meditations was the establishment of a firm foundation upon which to raise the sciences.23 Because Descartes scientific thought derives entirely from his metaphysics,24 he is able to sidestep the need to deal directly in his letter with the fact that his speculative physics overturns the speculative physics of Aristotle — the main points that Descartes address in his letter, viz., proving the existence of God and the immortality of the soul, are framed in terms of definitive proofs that can be used to combat atheism, materialism, and religious skepticism.25

Descartes’ project of providing a firm metaphysical foundation for the sciences is carried out according to the established template of the Scholastic philosophers, consisting of a synthesis of speculative metaphysics and Christian theology. But by taking a reductionist approach to the history of philosophy, and indeed to the act of philosophizing itself, at one stroke Descartes is able to critique and sweep aside the writings of his Scholastic predecessors with his claims of logical soundness and indubitability for the proofs in the Meditations.26 Descartes’ conception of one universal science, whose “roots are metaphysics, the trunk is physics, and the branches emerging from the trunk are all the other sciences…,”27 required that the method used for augmenting the sciences be single, in order that truth could be demonstrated in a systematic order. The indisputability of Aristotle’s indemonstrable principles for reasoning was transformed, under the auspices of the Cartesian method, into the test of indubitability for arriving at epistemological certainty in derived propositions.

Descartes synthesis of speculative metaphysics and Christian theology differs, then, from the Scholastic’s metaphysics and theology in that the aim of discovering a method from which to derive indubitable metaphysical principles with which to augment physics and all the other branches of science was never present for Scholastic philosophers such as Aquinas. For Descartes, the theological imperative to demonstrate the existence of God and the immortality of the soul developed out of a rationale opposed to the Aristotelian/Scholastic concept of theoria (the contemplation of truth) as the utmost goal of philosophizing.28

Descartes rejected not only the contemplation of truth as the goal of philosophic activity by replacing it with an end in practical activity, but took skepticism as his chief philosophic enemy from the beginning, rather than the thought of Aristotle and the Scholastics.29 Moreover, Descartes’ held that the rational proofs found in the writings of the Schoolmen for the existence of God and the immortality of the soul failed to attain their objective, and amounted in the end to mere demonstrations that the truths of faith and the truths of reason do not lie in opposition to each other; or, that there can not exist something which is both true and not true at the same time.

Such demonstrations, Descartes held, were insufficient to combat the tendency in the 17th century toward atheism, materialism, and religious skepticism. Only the perception of truth impressed with such force and vivacity that the mind cannot help but assent to it could be a sufficient criterion for the test of the indubitability of knowledge — what is true is what the mind perceives “clearly and distinctly.”

1 It should be noted that, in regard to his Principles of Philosophy (1644), Descartes’ desire to have his textbook adopted and instituted into the Jesuit educational programme led him to soften his tone concerning the anti-Aristotelian and anti-Scholastic positions found in such works as his Discourse on the Method (1637) and Meditations (1641). Writing to his former teacher, Charlet, in October 1644, Descartes states in regard to the contents of his Principles that, “I know that people have thought my views were new; yet they will see here that I do not use any principles which were not accepted by Aristotle and by all those who have ever concerned themselves with philosophy. People have also imagined that my aim was to refute the received views of the Schools, and to try to render them absurd; but they will see that I do not discuss them any more than I would if I had never learnt them” (AT IV, 141; CSMK 3, p. 238); and four months later, again writing to Charlet, Descartes expresses his wish that his textbook would “serve effectively to explain the truths of the faith without, moreover, contradicting the writings of Aristotle” (AT IV, 157; CSMK 3, p. 240).

2 DA, p. 558 (413b 25). Cf. DA, p. 548 (408b 24): “The incapacity of old age is due to an affection not of the soul but of its vehicle… Thus it is that in old age the activity of mind or intellectual apprehension declines only through the decay of some other inward part; mind itself is impassable.”

Regarding Aristotle’s opinion of the immortality of the soul in De anima, and how those opinions formed a basis for debate among Christian philosophers C.F. Fowler notes that, “His [Aristotle’s] enigmatic comments throughout the De anima on the possibility of the survival of the human soul only added to the difficulties for his Christian followers and gave rise to the various schools of interpretation.” Descartes On the Human Soul: Philosophy and the Demands of Christian Doctrine (International Archive of the History of Ideas, 160; Kluwer Academic Publishers, Dordrecht, Boston, London, 1999), p. 80. Brackets mine.

3 Cf., SCG 2, 68: 12: “Above all these forms [nutritive and sensitive souls], however, is a form like to higher substances even in respect of the kind of knowledge proper to it, namely, understanding. This form, then, is capable of an operation which is accomplished without any bodily organ at all. And this form is the intellective soul; for understanding is not effected though any bodily organ. That is why this principle, the intellective soul by which man understands and which transcends the condition of corporeal matter, must not be wholly encompassed or imbedded in matter… This is proved by its intellectual operation, wherein corporeal matter has no part. But since the human soul’s act of understanding needs powers — namely, imagination and sense — which function through bodily organs, this itself shows that the soul is naturally united to the body in order to complete the human species.”

4 Cf. AT VII, 3; CSM 2, p. 4: In his Dedicatory Letter, Descartes is in earnest with his assertion that, “I think there is no more useful service to be rendered in philosophy than to conduct a careful search, once and for all, for the best of these arguments [for the existence of God and the immortality of the soul], and to set them out so precisely and clearly as to produce for the future a general agreement that they amount to demonstrative proofs.” Brackets mine.

5 AT VII, 3; CSM 2, p. 4.

6 In 1613, Aquaviva, the General of the Jesuit order, renewed the Jesuit’s commitment to Thomas’ theology.

7 AT VII, 3; CSM 2, p. 4, brackets mine. Cf. DA, “To attain any assured knowledge of the soul is one of the most difficult things in the world,” p. 535, 402a 10. Cf. Discourse on the Method, “But many are convinced that there is some difficulty in knowing God and even knowing what their soul is,” AT VI, 37; CSM 1, p. 129.

8 DA, p. 561, 415a 15. Brackets mine.

9 Cf. Aristotle’s Metaphysics: “There are… some who raise a difficulty by asking, who is to be the judge of the healthy man, and in general who is likely to judge rightly on each class of questions. But such inquiries are like puzzling over the question whether we are now asleep or awake. And all such questions have the same meaning. These people demand that a reason shall be given for everything; for they seek a starting-point, and they seek to get this by demonstration, while it is obvious from their actions that they have no conviction. But their mistake is what we have stated it to be; they seek a reason for things for which no reason can be given; for the starting-point of demonstration is not demonstration,” p. 747-748 (1011a 1- 15).

10 AT VII, 4; CSM 2, p. 4.

11 In order for the philosophical proof for the immortality of the soul to be consistent with the Church’s doctrine, Aquinas postulated that God would have to act in order to preserve the soul after the death of the body: “Separated souls know some singulars but not all (even those that are temporally present). For evidence on this we should consider that there are two modes of understanding. One is by abstraction from sense images, and in this manner singulars cannot be known by the intellect directly… The other manner of understanding is by the infusion of species [per influentiam specierum] by God, and according to this manner the intellect can know singulars… immaterial substances can know singulars by way of species which are participated likenesses of the divine essence,” ST, 1a, 89, 4, reply; pp. 149-151. Brackets mine.

12 Cf. footnote 3 in CSM 2, p. 10, where the additional phrase from the French translation of the Meditations, “…or the soul of man, for I make no distinction between them,” is noted in relation to the passage from the original text that reads, “And it follows from this that while the body can very easily perish, the mind is immortal by its very nature.”

C.F. Fowler note of Descartes’ predominant use of the term mens over anima, animus, ingenium, and spiritus in the Meditations to describe the human soul (Fowler 1999, pp. 161-175). Fowler concludes with the observation that, “The novelty of the Cartesian notion of the human soul was highlighted by a refusal of the traditional vocabulary and the deliberate choice of the word mens,” ibid., p. 186.

13 AT VII, 2; CSM 2, p. 3. Brackets and italics mine. The Latin original is as follows: “…videmur admoneri ea omnia quae de Deo sciri possunt, rationibus non aliunde petitis quam ab ipsamet nostra mente posse ostendi.”

14 Third Meditation, AT VII, 51; CSM 2, p. 35: “…when I turn my mind’s eye on upon myself, I understand that I am a thing which is incomplete and dependent on another and which aspires without limit to even greater and better things; but I also understand at the same time that he on whom I depend has within him all those greater things, not just indefinitely and potentially but actually an infinitely, and hence that he is God.”

15 Third Meditation, AT VII, 51; CSM 2, p. 35.

16 The fact that man is created in the “likeness” or “image” of an infinite and perfect God has its parallel in: 1) infinite — the human will that extends indefinitely; 2) perfection — the mind’s reflexive apprehension of clear and distinct ideas.

17 Cf. Third Meditation, AT VII, 42; CSM 2, p. 29: “An although one idea may perhaps originate from another, there cannot be an infinite regress here; eventually one must reach a primary idea, the cause of which will be like an archetype which contains formally [and in fact] all the reality [or perfection] which is present only objectively [or representatively] in the idea. So it is clear to me, by the natural light, that the ideas in me are like [pictures, or] images which can easily fall short of the perfection of the things from which they are taken, but which cannot contain anything greater or more perfect.” Brackets in original.

18 Thomas Aquinas, Summa Contra Gentiles, 2, 46: 2.

19 Cf. SCG 2, 77: 2: “…the intellectual soul itself remains potential with respect to the determinate likeness of things that can be known by us, namely, the natures of sensible things. It is the phantasms which present these determinate sensible natures to us. But these phantasms have not yet acquired intelligible actuality, since they are likenesses of sensible things even as to material conditions, which are the individual properties, and, moreover, the phantasms exist in material organs. Consequently, they are not actually intelligible.”

20 In a letter to Mersenne of January 28, 1641, Descartes writes in regard to his physics, “…I may tell you, between ourselves, that these six Meditations contain all the foundations of my physics. But please do not tell people, for that might make it harder for supporters of Aristotle to approve them. I hope that readers will gradually get used to my principles, and recognize their truth, before they notice that they destroy the principles of Aristotle,” AT III, 297-298; CSMK 3, p. 173. Like Aristotle’s, Descartes physics are founded on his metaphysics; hence, to destroy the principles of Aristotle’s physics is to cast doubt on the validity of his metaphysics as well — which Descartes does not fail, in his Meditations, to do.

21 Letter to the Sorbonne, AT VII, 2; CSM 2, p. 3.

22 Letter to the Sorbonne, AT VII, 3; CSM 2, p. 4.

23 “And finally, I was strongly pressed to undertake this task [producing demonstrative proofs for the existence of God, and that the human mind is distinct from the body] by several people who knew that I had developed a method for resolving certain difficulties in the sciences…” AT VII, 3; CSM 2, p. 4. Brackets mine.

24 In a letter to Mersenne of November 11, 1640, Descartes discusses some possible difficulties in the Sorbonne’s reception of his Meditations, which he refers to as his “metaphysics, due to controversies that might arise concerning certain other projected publications: “It might also hold up the approbation of the Sorbonne, which I want, and which I think may be very useful for my purposes, for I must tell you that the little book on metaphysics which I sent you contains all the principles of my physics.” (AT III, 233; CSMK 3, p. 157).

25 “What I have done is to take merely the principle and most important arguments and develop them in such a way that I would now venture to put them forward as very certain and evident demonstrations. I will add that these proofs are of such a kind that I reckon they leave no room for the possibility that the human mind will ever discover better ones.” (AT VII, 4; CSM 2, p. 4).

Contra the materialistic view of the soul propounded by early natural philosophers, Descartes briefly alludes to such claims in the Second Meditation: “But as to the nature of this soul, either I did not think about this or else I imagined it to be something tenuous, like a wind or fire or ether, which permeated my more solid parts.” (AT VII, 26; CSM 2, p. 17). Cf. SCG: “This, then, does away with the error of the early natural philosophers. Who supposed that no substance exists except the corporeal, and who therefore said that the soul is a body, either fire or water or air, or something of the kind…” (2, 49: 11). Cf. DA, p. 540-542 (405a 5-505b 30) for Aristotle’s review of his predecessor’s opinions of the soul as “either an element, or constructed out of the elements.” The respective summaries of the opinions of early natural philosophers found in the writings of Descartes and Aquinas’ are an obvious echo of remarks made in Aristotle’s treatise on the soul.

26 “I do not think that the diversity of the opinions of the scholastics makes their philosophy difficult to refute. It is easy to overturn the foundations on which they all agree, and once that has been done, all their disagreements over detail will seem foolish.” (AT III, 232; CSMK 3, p. 156).

27 Fifth Set of Objections, AT VII D; CSM 1, 186.

28 Cf. Nicomachean Ethics, “…the activity of God, which surpasses all others in blessedness, must be contemplative; and of human activities, therefore, that which is most akin to this [contemplation] must be most of the nature of happiness,” p. 1104 (1178b 20). Brackets mine. Cf. SCG 1, 1: 2: “The ultimate end of the universe must… be the good of an intellect. This good is truth. Truth must consequently be the ultimate end of the whole universe, and the consideration of the wise man aims principally at truth.”

29 Cf. Frederick Copleston, S. J., A History of Philosophy: Modern Philosophy: Descartes to Leibniz, volume 4 (Image Books, Garden City, New York, 1960), p. 80.