Rene Descartes is widely considered to be the father of modern philosophy. His seventeenth-century “Cartesian experiment” represented Western civilization’s philosophical and epistemological break from Medieval Scholasticism. Thomistic scholar Etienne Gilson remarks that although Descartes “came too late on the scene to kill scholasticism…it remains true that [he] drew up the death certificate.”1 To understand how this came to pass, one must begin by examining the intellectual forces competing during the sixteenth and seventeenth centuries.
Scholasticism, characterized by Michael J. Mahony as “the system of Aristotle corrected and developed, so as to bring it into harmony with sound reason and the truths of Christianity,” found its most thorough and enduring expression during the thirteenth century in the philosophy of Saint Thomas Aquinas.2 Scholastic thought dominated the Catholic Church’s schools, and, in an age when the Church wielded such powerful influence on society, it thus dominated the intellectual life of all Western culture. Gilson notes, however, that with the nominalism of William of Ockham taking root in the European universities in the fourteenth century, Scholasticism began to degenerate into Skepticism.3 Philosopher Richard Popkin explains that:
Scepticism…had its origins in ancient Greek thought. In the Hellenistic period the various skeptical observations and attitudes of earlier Greek thinkers were developed into a set of arguments to establish either (1) that no knowledge was possible, or (2) that there was insufficient and inadequate evidence to determine if any knowledge was possible, and hence that one ought to suspend judgment on all questions concerning knowledge. The first of these views is called Academic scepticism, the second Pyrrhonian scepticism.4
Pyrrhonism, surviving mainly in the writings of Sextus Empiricus (ca., A.D. 200), experienced a full-fledged revival in Europe during the sixteenth century. The Pyrrhonists “tried to avoid committing themselves on any and all questions, even as to whether their arguments were sound….This state of mind then led to a state of ataraxia, quietude, or unperturbedness, in which the sceptic was no longer concerned or worried about matters beyond appearances.”5 The revival of Pyrrhonism, led by Michel de Montaigne, coincided with the intellectual crisis brought on by the Reformation.6 The arguments of the Pyrrhonists, used by both Reformers and Counter-Reformers, were a significant influence on the theological battles of the period. As Popkin explains, one of the central issues of those battles was that of the criterion of certainty:
In the struggles between the old established order of the Catholic Church and the new order of the Reformers, the Reformers had to insist on the complete certainty of their cause…. In order to buttress their case, the Reformers sought to show that the Church of Rome had no guarantee of its professed religious truths, that the criterion of traditional authority carried with it no assurance of the absolute certitude of the Church’s position, unless the Church could somehow prove that traditional authority was the true criterion.
On the other hand, the Catholic side could and did attack the Reformers by showing the unjustifiability of their criterion, and the way in which the claims of certainty of the Reformers would lead to a complete subjectivism and scepticism about religious truths.7
The use of Pyrrhonist arguments, however, was not confined to the theological realm but spilled over into other areas of human knowledge, including the sciences, which, up until then were based on Aristotelian principles.8 Popkin comments, “What the Reformation was supposed to have accomplished in religion, (according to the French Counter-Reformers), reducing all views to mere opinions to be judged by their plausibility, had also occurred in philosophy and science.”9 Though Cartesian epistemology did ultimately affect the approach taken to theological issues,10 it was the Pyrrhonist threat posed to the sciences that inspired Descartes to attempt a new intellectual foundation for the edifice of man’s knowledge. In order to lay that foundation, however, Descartes maintained that Scholasticism, for reasons to be explained later, would have to be abandoned for a “better” method of epistemology which he hoped would forever dispense with the crisis of certainty incited by the Reformation.
Rene Descartes was born in 1596 in La Haye, France. His mother’s untimely death when he was only one, his chronically weak physical disposition, and his high regard for mathematics all helped contribute to his vision that the sciences could be greatly expanded for the practical benefits of mankind. As a youngster he was educated at the Jesuit college of La Fleche and trained in the Scholasticism he would later challenge. He enlisted in the Dutch and later the Bavarian armies mainly because it gave him time for solitary meditation. Bertrand Russell says “it was in Bavaria, during the winter 1619-1620, that he had the experience he describes in the Discours de la Methode. The weather being cold, he got into a stove in the morning, and stayed there all day meditating.”11 The practice of meditation was quite suited to Descartes’ tendency to look inward for knowledge as he reportedly came out of the stove with a well-developed philosophy, which he later published in Discourse (1637) and Meditations on First Philosophy (1641). Meditations is reminiscent of traditional Christian meditation, but rather than attaining Christian virtue, Descartes sought a better acquaintance with his own cognitive faculties in hopes of restraining man’s propensity to err.12
Rules for valid thinking. Descartes’ attempt at a new epistemological system included at the outset his rules for the avoidance of making errors in reasoning. Christian apologist and philosopher Norman Geisler summarizes:
The corrective for error is found in four rules of valid thinking. First, the rule of certainty states that only indubitably clear and distinct ideas should be accepted as true. Second, the rule of division affirms that problems must be reduced first to their simplest parts. Third, the rule of order declares that we must proceed in our reasoning from the simplest to the most complex. Finally, the rule of enumeration demands that we check and recheck each step of the argument to make sure no mistake has been made. By following this method Descartes was assured that error could be overcome and certainty could be attained in our knowledge of God.13
Scholar George Heffernan adds that “the requirements of the Cartesian method…were that one begin with what were so simple and evident as to be indubitable, and that in the progression from the simple to the complex no step be taken which were not similarly indubitable.”14
Mathematicism. Descartes begins the Discourse by confessing his personal embarrassment over the doubts and errors that he had accrued over his lifetime, allegedly due to his blind acceptance of Aristotle and the Scholastics,15 which Professor John Carriero says he considered little more than the “systematization of the uncritical worldview of the common man.”16 He furthermore laments that science was doomed to a lesser fate than it deserved because it was built upon the traditional philosophy which was too weak of a structure to support its promising and practical enterprise.17 Descartes expressed contempt for Aristotelianism because though “it has been cultivated for many ages by the most excellent minds that have lived…there is still not to be found in it anything about which one does not dispute.”18 In this context, Descartes writes that he “delighted, above all, in mathematics, because of the certitude and the evidence of its reasonings” and expresses astonishment that “its foundations being so firm and so solid, one had built nothing more lofty thereupon.”19
Descartes, thus, sought to use the reasonings of mathematics, particularly geometry, to apply to and give epistemological certitude to the general sciences. Gilson writes that “the principle that lies at the root of Cartesian mathematicism is that, since the most evident of all sciences is also the most abstract, it would be enough to make all the other sciences as abstract as mathematics in order to make them just as evident.”20 Aristotelian philosophy recognized varying degrees of certitude depending on the nature of the object studied. But, as philosopher Jacques Maritain writes, Descartes desired an epistemological system with “no varying degrees of certitude.” Accordingly, “Mathematics becomes the Queen of the Sciences and the norm for all knowledge.”21 Historian Frederick Copleston notes: “Descartes’ theory that all the sciences are ultimately one science and that there is one universal scientific method separates him at once from the Aristotelians. The latter believed that the different subject-matters of different sciences demand different methods.”22 Of course, different methods would yield varying degrees of certitude which is exactly what Descartes insisted against, since to him only absolute certitude in all areas of the sciences could ultimately defeat skepticism.23
Methodic Doubt. Descartes’ obsession with certitude placed him in direct conflict with Montaigne and the seventeenth-century Pyrrhonists. Gilson says that the entire Cartesian system was a direct response to the skepticism of Montaigne. Because Descartes “was dedicated to the proposition that all sciences were one…[he] could see now why Montaigne had found himself condemned to a complete scepticism.” Since Montaigne, unlike the geometer Descartes, had not found the key to universal knowledge, he justifiably resigned to knowing nothing at all.24 In responding to Montaigne and the Pyrrhonists, Descartes employed the doubt of skepticism with a view toward defeating skepticism. Descartes himself contrasts his method of doubt with the despair of the skeptics “who doubt only in order to doubt, and who affect being always undecided; for, on the contrary, my whole plan tended only toward assuring me, and toward casting aside the shifting earth and the sand in order to find the rock or the clay.”25
Descartes’ epistemology is thus generally classified as Methodic Doubt. Joseph Owens explains: “This Cartesian doubt required a thoroughgoing mental asceticism to rid the mind of its accustomed way of thinking, a way that had grown upon it unwittingly since childhood. But need the doubt mean continued skepticism? That was anything but the author’s intention.”26 The doubt of the skeptic intentionally ended in a conclusion of doubt. As Copleston observes, however, Cartesian doubt “is methodic in the sense that it is practised not for the sake of doubting but as a preliminary stage in the attainment of certainty and in sifting the true from the false, the certain from the probable, the indubitable from the doubtful.”27 Copleston adds that Cartesian doubt is methodic and provisional rather than permanent because “Descartes does not necessarily aim at substituting new propositions for those in which he formerly believed.”28
Descartes, thus, used the method of doubt in his attempt to permanently cast off the epistemological scourge of skepticism. To do so, however, he not only had to directly challenge the Pyrrhonists, but also the Scholastics whose Aristotelianism, in his mind, left the sciences forever without the security of absolute certitude. Though his philosophical conclusions would reveal much common ground with the Scholastics, his method differed greatly from that school and was ultimately found wanting as an adequate foundation for those very conclusions.
Doubting the senses. Scholastic epistemology placed great emphasis on the role of the senses. Aquinas, following Aristotle, “thought that the senses as well as the intellect were necessary for human understanding.” Additionally, Aquinas taught, it was indirectly through the senses that human beings have knowledge of God and their own intellect.29 Gary Hatfield explains: “At the core of the Aristotelian conception of the knower lay a sense-based epistemology, which was distilled into the slogan, ‘Nothing is in the intellect that was not first in the senses.’ As elaborated by Thomas Aquinas and subsequent Aristotelians, this implied that all knowledge, including knowledge of God, the soul, and the truths of mathematics, is attained by the intellectual abstraction of universals from sensory particulars.”30 Descartes disagreed, remarking “that the ideas of God and the soul have never been [in the senses].”31 Descartes did not ultimately deny that the senses played any epistemological role; he did however argue that they occasionally mislead and cannot be indubitable trusted. He believed that the indiscriminate judgments of childhood caused him to naively accept whatever his senses reported, even when those reports were not an accurate representation of the real world.32 Only a severely ascetic method of doubt would be able to rid the mind of such naïveté. For Descartes, if the senses have deceived even once, then they lack the certitude required by mathematicism: “Whatever I have up till now accepted as most true I have acquired either from the senses or through the senses. But from time to time I have found that the senses deceive, and it is prudent never to trust completely those who have deceived us even once.”33
Assuming then that the senses sometimes deceive, how does one adjudicate between true and false sensations? The senses themselves, according to Descartes, do not possess such an adjudicating faculty. And because the sometimes-deceptive senses lack such a faculty, how can one with absolute certitude be sure that he has hands and feet and a body at all since that knowledge is acquired through such untrustworthy sources? Of course, only madmen, “whose brains are so damaged by the persistent vapors of melancholia that they firmly maintain they are kings when they are paupers, or say they are dressed in purple when they are naked, or that their heads are made of earthenware, or that they are pumpkins, or made of glass,” really have any such doubts about the existence of their own bodies.34 But when Descartes recalls that he “regularly has all the same experiences while asleep as madmen do when awake,”35 and acknowledges the lack of a faculty to indubitably distinguish between waking and sleeping, he confesses that it is possible that he is completely mistaken about all external reality.
Though the so-called dream argument was objected to by contemporary critic Thomas Hobbes as merely a rehash of Plato, Descartes defends its use by replying that he “was not trying to sell them as novelties” but could hardly have left them out any more than a physician “can leave out the description of a disease when he wants to explain how it can be cured.”36 Descartes considered the illusions of dreaming to be ample evidence that we can sometimes be deceived about what our senses are allegedly reporting. For this reason, he concluded that “physics, astronomy, medicine, and all other disciplines which depend on the study of composite things, are doubtful; while arithmetic, geometry and other subjects of this kind, which deal only with the simplest and most general things, regardless of whether they really exist in nature or not, contain something certain and indubitable.”37
Doubting first principles. In the immediate wake of the dream argument, Descartes’ temporary resolve was that “whether I am awake or asleep, two and three added together are five, and a square has no more than four sides. It seems impossible that such transparent truths should incur any suspicion of being false.”38 Cartesian doubt, however, takes a malevolent twist as Descartes questions how he can have absolute certainty that “[God] has not brought it about that there is no earth, no sky, no extended thing, no shape, no size, no place, while at the same time ensuring that all these things appear to me to exist just as they do now?”39 Perhaps God systematically deceives him so that he goes wrong every time in adding two plus three or counting the sides of a square. Believing, however, that God is supremely good, Descartes postulates “that not God, who is supremely good and the source of truth, but rather some malicious demon of the utmost power and cunning has employed all his energies in order to deceive me.”40 Since the very nature of deception entails that the deceived person does not know that he is being deceived, Descartes does not seek to prove but merely speculate about the possibility of such malevolent deception. The mere possibility of such, as Descartes sees it, would mean that even a priori first principles, like mathematics, must be called into doubt. Though Descartes does not explain the apparent contradiction of a supremely Evil Spirit in which omnipotence exists in isolation from the perfection of goodness,41 he has nevertheless made his point that not only the senses but also the “first principles or axioms of the ideal order” cannot be trusted.42 Moreover, at the beginning of the Second Meditation, Descartes expresses doubt about his own memory, supposing that even it continually lies to him.43
The cogito. Thus far, all the traditional sources of knowledge have been shown to be less than indubitable, just as the Pyrrhonists had contended. Descartes’ goal, however, was not to mimic the skeptics but to defeat them. He only had to find one immovable and certain truth from which he could construct the whole of his philosophy. He writes that “Archimedes used to demand just one firm and immovable point in order to shift the entire earth; so I too can hope for great things if I manage to find just one thing, however slight, that is certain and unshakeable.”44 After sacrificing the senses and the a priori on the altar of methodic doubt, Descartes’ Meditations finally descended upon the indubitable and unanalyzable pivot point his philosophy required: “So after considering everything very thoroughly, I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind.”45 The cogito, as the assertion “I am, I exist” is commonly referred to, is the one proposition that is impervious to the rigors of methodic doubt. It is resistant “because only it can reassert itself in a unique and evident intuition when confronted with reiteration of doubt.”46 Geisler explains: “The one thing that I cannot doubt is that I am doubting. But if I am doubting, then I am thinking (for doubt is a form of thought).”47 But since thought presupposes a thinker, even the malevolent demon, powerful and cunning as he may be, cannot deceive Descartes about his own existence. Since he thinks, he is. Descartes assures himself not only that the cogito is true, but is necessarily true whenever it is uttered. All forms of knowledge, sensory and a priori, can be subjected to doubt and discarded for lack of certitude. But the cogito, the first principle of Descartes’ epistemology, remains standing as the (only) rock on which the edifice of human knowledge can possibly be constructed. Although the cogito was long previously discovered and used by the likes of Aristotle and Saint Augustine, it was the seventeenth-century rationalist Rene Descartes who championed this certitude of his own existence as the cornerstone of an epistemological revolution.48
The “I” as a thinking thing. The discovery of the cogito brought an abrupt end to Descartes’ tumultuous dismantling of knowledge, but the task of knowing how to build upon this first principle still loomed ahead. Mahony says, “as a geometrician gradually builds up, by the aid of a few axiomatic principles…so it was Descartes’ hope to find his whole system of philosophy implicitly contained in his first principle.”49 The immediate problem confronting the meditator was to explain the essence of the “I” of the cogito. Carriero points out that although it is not significant that Descartes sought to know that he is independent of the existence of body, “his announcement immediately following the cogito passage that he will try to discover what he is, while in a state of uncertainty concerning the existence of body, does constitute a striking break with the Aristotelian tradition.”50 Since methodic doubt has taught Descartes that the idea of body is obscure and confused, he denies that his essence consists of any material thing (extension).51 His meditation leads him to conclude that “thought; this alone is inseparable from me. I am, I exist – that is certain. But for how long? For as long as I am thinking. For it could be that were I totally to cease from thinking, I should totally cease to exist.”52 Hence, the “I” of the cogito is merely a thing that thinks, that is, a “thing that doubts, understands, affirms, denies, is willing, is unwilling, and also imagines and has sensory perceptions.”53 And should the “thinking thing” cease to think it would likewise cease to be.54
Knowledge of the mind. Because the “I” is nothing more than a thinking thing, Descartes concludes that the essence of the mind is known better than anything else. “For no matter how many attributes we recognize in any given thing, we can always list a corresponding number of attributes in the mind which it has in virtue of knowing the attributes of the thing; and hence the nature of the mind is the one we know best of all.”55 For example, a piece of wax appears to have certain characteristics discernible by the senses such as scent, color, shape and size. But if heat is applied to the wax, it seemingly loses all those same characteristics. But no one denies that it is the same piece of wax, do they? Apparently, the wax is “not after all the sweetness of the honey, or the fragrance of the flowers, or the whiteness, or the shape, or the sound, but was rather a body which presented itself to me in these various forms….[The wax is] merely something extended, flexible and changeable.”56 Because whether or not the wax exists the sensations and imaginations entail that the mind exists, Descartes concludes that the substance of the wax is really perceived by the mind alone.57
Or what if he looks out his window and sees men in coats and hats crossing the square; does he really see men? Or does he merely judge by the mind that they are men and not mere automatons concealed by hats and coats? Like the wax example, he concludes that “something which I thought I was seeing with my eyes is in fact grasped solely by the faculty of judgement which is in my mind…. [Thus], “I now know that even bodies are not strictly perceived by the senses or the faculty of imagination but by the intellect alone, and that this perception derives not from their being touched or seen but from their being understood; and in view of this I know plainly that I can achieve an easier and more evident perception of my own mind than of anything else.”58 Far from the Scholastic axiom that the mind is known indirectly and remotely, Descartes postulates that not only is the mind known directly, but it is also known better than anything else. Carriero contrasts Cartesian and Thomistic epistemology:
Descartes rejects the Aristotelian thesis that an account of understanding begins with a characterization of the object that the intellect apprehends, and works backward… through principles concerning the identity of knower with known to a characterization of the nature of the intellectual self. It would be impossible for Aquinas to begin his account of what an (existing) intellect is without positing the existence of material particulars that share universal features. In the Second Meditation Descartes’ attempt to offer a full account of the nature of an (existing) mind under the assumption that no bodies exist is, in the main, a response to the Aristotelian claim that the intellectual self can be known only remotely.59
Clear and distinct. In contrast to the obscure and confused knowledge of bodies, the clarity and distinctness of the cogito makes it indubitable. Therefore, the second constructive axiom that Descartes lays down is the “general rule that whatever I perceive very clearly and distinctly is true.”60 As Geisler observes, Descartes considered true only “those ideas known by rational intuition as self-evident…[or], those which are (geometrically) deducible from self-evident ideas.”61 Mahony notes that “this characteristic of his own existence he then generalized and set up as the criterion, standard or test of all truth.”62 Copleston writes that “this criterion of truth was doubtless suggested to Descartes by mathematics. A true mathematical proposition imposes itself, as it were, on the mind: when it is seen clearly and distinctly, the mind cannot help assenting to it. Similarly, I affirm the proposition, I think, therefore I am, not because I apply some extrinsic criterion of truth, but simply because I see clearly and distinctly that so it is.”63 Popkin emphasizes the importance of this axiom because by it Descartes hopes to bridge the gap from thought to thing.64
Different types of ideas. Before attempting to leap from thought to thing via demonstration of God’s existence, Descartes classifies the types of thoughts that he finds within himself to see “which of them can properly be said to be the bearers of truth and falsity… [saying], “among my ideas, some appear to be innate, some to be adventitious, and others to have been invented by me.”65 Challenging the validity of adventitious ideas, Descartes writes that “the chief question at this point concerns the ideas which I take to be derived from things existing outside me: what is my reason for thinking that they resemble these things? Nature has apparently taught me to think this.”66 Despite this apparent guidance of Nature, Descartes claims that he has “often discovered a great disparity between an object and its idea in many cases.”67 So it is merely “blind impulse that has made me believe up till now that there exist things distinct from myself which transmit to me ideas or images of themselves through the sense organs or in some other way.”68
Because those ideas which are supposedly derived from external existence are so notoriously untrustworthy, Descartes finds himself instead searching for a way to know from his innate ideas whether or not external objects actually exist. Descartes’ reliance on innate ideas for human epistemology bears striking resemblance to the Thomistic theory of angel knowledge. As Maritain points out, the angel intellect is “always in act with regard to its intelligible objects, does not derive its ideas from things, as ours does, but has them direct from God, Who infuses them into it when He creates it.”69 Also reminiscent of Descartes, angelic cognition “is independent of external objects” but rather dependent on the knowledge of God.70 Therefore, “The idea thus becomes the sole term immediately attained by thought, the thing, portrait or representation, itself first known before making anything else known.”71 Although Maritain would admit that Descartes’ epistemology cannot be reduced merely to angel knowledge, there are nevertheless more than apparent similarities.72
Descartes’ unyielding reliance on innate ideas,73 or rationalism, clearly separates him from empiricists like Aristotle and the Scholastics who emphasized the senses. Geisler writes that rationalism “stresses the mind in the knowing process…[and] holds to an a priori aspect to human knowledge, that is, something independent of sense experience.”74 Furthermore, as is clearly seen in Descartes’ epistemology, rationalists tend to argue for innate ideas or principles.75 And although “it is not uncommon for empiricism to lead to skepticism or materialism,” rationalists like Descartes, on the other hand, “tend to argue for the existence of God” via the ontological argument.76 Cartesian rationalism, in fact, requires the existence of God for epistemic certitude. Until Descartes knows that God exists, he cannot know that he is not completely alone in an imaginary universe of his own devising.
A posteriori proof of God’s existence. Descartes applies the law of causality to the innate ideas which are in his mind independent of external reality. Since “there must be at least as much reality in the efficient and total cause as in the effect of that cause” then it follows that “something cannot arise from nothing, and also that what is more perfect – that is, contains in itself more reality – cannot arise from what is less perfect.”77 Despite the fact that his sudden and convenient acceptance of the law of causality is inconsistent with his previous demolition of all first principles (which he has yet to reconstruct), Descartes determinately concludes:
If the objective reality of any of my ideas turns out to be so great that I am sure the same reality does not reside in me, either formally or eminently, and hence that I myself cannot be its cause, it will necessarily follow that I am not alone in the world, but that some other thing which is the cause of this idea also exists. But if no such idea is to be found in me, I shall have no argument to convince me of the existence of anything apart from myself.78
Within his mind he recognizes “ideas which variously represent God, corporeal and inanimate things, angels, animals and finally other men like myself.”79 With the exception of the idea of God, however, he finds nothing in any of these ideas “which is so great or excellent as to make it seem impossible that it originated in myself. For if I scrutinize them thoroughly and examine them one by one, in the way in which I examined the idea of the wax yesterday, I notice that the things which I perceive clearly and distinctly in them are very few in number.”80 But the idea of God, that is, that “substance that is infinite, eternal, immutable, independent, supremely intelligent, supremely powerful, and which created both myself and everything else (if anything else there be)” could not have arisen solely from within the mind. It follows, therefore, that God necessarily exists.81 Descartes reasons that his idea of God could not have been invented by him:
I clearly understand that there is more reality in an infinite substance than in a finite one, and hence that my perception of the infinite, that is God, is in some way prior to my perception of the finite, that is myself. For how could I understand that I doubted or desired – that is, lacked something – and that I was not wholly perfect, unless there were in me some idea of a more perfect being which enabled me to recognize my own defects by comparison.82
And what is it about this idea of God that makes His existence indubitable? Nothing other than that it is “utterly clear and distinct, and contains in itself more objective reality than any other idea; hence there is no idea which is in itself truer or less liable to be suspected of falsehood.”83 Thus, the idea of God contains within it the same clarity and distinctiveness that is contained in the cogito, which consequently means that it is a true idea. Geisler summarizes the a posteriori theistic proof of the Third Meditation:
I doubt. But if I doubt, I am imperfect; for a lack in knowledge is an imperfection. But if I know what is imperfect, I must have knowledge of the perfect; otherwise I would not know it is not-perfect. However, knowledge of the perfect cannot arise from an imperfect mind, since there cannot be an imperfect source or basis of what is perfect. Therefore, there must be a perfect Mind (God) who is the origin of the idea of perfection I have.84
Or as Gilson puts it, “since the very act of doubting implies the notion of perfection, which is one with the notion of God, we have just as much right to say: I doubt, hence God is, as to say: I doubt, hence I am.”85
The nature of God. From the existence of God, Descartes immediately sets out to demonstrate certain attributes of God that are vital to his epistemology. As Gilson notes, Cartesian rationalism discovers “the mind first, God next, and only then the external world.”86 Having already identified his own nature, the last remaining obstacle to discovering the external world is a clear and distinct understanding of the nature of God. Descartes reasons that “since I am a thinking thing and have within me some idea of God, it must be admitted that what caused me is itself a thinking thing and possesses the idea of all the perfections which I attribute to God.”87 In addition to God being a thinking thing, He is also a simple being with inseparable attributes.88 Most importantly, however, Descartes echoes his earlier supposition that “it is clear enough…that [God] cannot be a deceiver, since it is manifest by the natural light that all fraud and deception depend on some defect.”89 Because within Descartes’ clear and distinct idea of God there is no defect, in the reality of God there cannot be one.
The assertion of God’s truthfulness, as will become apparent in the Sixth Meditation, is indispensable to Descartes’ attempt to leap from thought to thing and prove that the external world actually exists. God’s very existence, in fact, is the only legitimate avenue to the discovery of other knowledge:
So clear is this conclusion (that God exists) that I am confident that the human intellect cannot know anything that is more evident or more certain. And now, from this contemplation of the true God, in whom all the treasures of wisdom and the sciences lie hidden, I think I can see a way forward to the knowledge of other things.90
The cause of errors. Since God would never deceive Descartes, it must also be true that God would not give to him “the kind of faculty which would ever enable [him] to go wrong while using it correctly.”91 That being the case, Descartes spends the Fourth Meditation examining the cause of human error. He narrows down the possibilities to “two concurrent causes, namely on the faculty of knowledge which is in me, and on the faculty of choice or freedom of the will; that is, they depend on both the intellect and the will simultaneously.”92 Noteworthy is Descartes’ philosophy of the will as infinite and indifferent. Unlike the faculty of understanding which, admittedly, is “extremely slight and very finite,” the will on the other hand is “so great that the idea of any greater faculty is beyond my grasp.”93 The will is “not restricted in any way” and “the possibility of further increase in its perfection or greatness” is beyond comprehension.94 In comparing God’s will to his own, Descartes reasons that “although God’s will is incomparably greater than mine…in that it ranges over a greater number of items, nevertheless it does not seem any greater than mine when considered as will in the essential and strict sense.”95 In addition to being infinite, the will is also indifferent, at least in cases where the “intellect is wholly ignorant” or “does not have sufficiently clear knowledge at the time when the will deliberates.”96 Clear and distinct propositions compel assent; thus the will is free but not indifferent in such cases. Confused and obscure ideas, conversely, do not compel assent, leaving the will indifferent.
This meditation leads Descartes to the conclusion that the cause of human error is simply that “the scope of the will is wider than that of the intellect; but instead of restricting it within the same limits, I extend its use to matters which I do not understand. Since the will is indifferent in such cases, it easily turns aside from what is true and good, and this is the source of my error and sin.”97 That is, the faculty of the will has the ability to go beyond the appropriate bounds of the intellect. Error results in those cases when the will exceeds its “jurisdiction.” As Martha Bolton comments, “Error can occur when one affirms or denies what has been only confusedly or obscurely (vs. clearly and distinctly) understood.”98 Maritain again notes the considerable similarity between angelic and Cartesian epistemology:
I am mistaken only because I will have it so, my free will alone is to blame. And therefore human error is explained for Descartes in the same way as theologians explain angelic error…When [angels] err…they see in full light an object whose natural reality they completely apprehend…. And when they impetuously extend their affirmation beyond what they see, and give their assent precipitately…to a thing which is not evident to them, it is because they are carried away by the malice of their will….Such, according to Descartes, is man when he affirms and judges beyond what he perceives clearly and distinctly, from a weakness of his free will.99
Having indicted the will as the cause of error, Descartes develops a principle of restraint: “If, however, I simply refrain from making a judgement in cases where I do not perceive the truth with sufficient clarity and distinctness, then it is clear that I am behaving correctly and avoiding error. But if in such cases I either affirm or deny, then I am not using my free will correctly.”100 With the cause and cure for error having been identified, Descartes’ next step is an attempted escape from his previous doubts to see whether any certainty can be achieved regarding material objects.101
A priori proof for God. Before Descartes arrives at his argument for the reality and knowability of the external world, he first develops an a priori argument for the existence of God and discusses the specific role of God in epistemology. The Anselm-like a priori proof of the Fifth Meditation asserts that “it is quite evident that existence can no more be separated from the essence of God than the fact that its three angles equal two right angles can be separated from the essence of a triangle, or than the idea of a mountain can be separated from the idea of a valley.”102 Because existence is included in his clear and distinct idea of God, then it must be that God exists:
But from the fact that I cannot think of God except as existing, it follows that existence is inseparable from God, and hence that he really exists. It is not that my thought makes it so, or imposes any necessity on any thing; on the contrary, it is the necessity of the thing itself, namely the existence of God, which determines my thinking in this respect. For I am not free to think of God without existence (that is, a supremely being without a supreme perfection) as I am free to imagine a horse with or without wings.103
The a priori proof is so convincing that Descartes confesses to “having at least the same level of certainty [in God’s existence] as I have hitherto attributed to the truths of mathematics.”104
Role of God in epistemology. With the fear of the systematic deception of the malevolent demon having been removed by the knowledge of the existence of the omnibenevolent God, Descartes’ faith in mathematics, temporarily lost before the cogito, has been restored. As Popkin notes, “The demon having been exorcised from Heaven and Earth, there then remained no question about the truths of mathematics.”105 This restoration of mathematics and its epistemological connection to God is crucial:
Thus I see plainly that the certainty and truth of all knowledge depends uniquely on my awareness of the true God, to such an extent that I was incapable of perfect knowledge about anything else until I became aware of him. And now it is possible for me to achieve full and certain knowledge of countless matters, both concerning God himself and other things whose nature is intellectual, and also concerning the whole of that corporeal nature which is the subject-matter of pure mathematics.106
No one can have true knowledge unless they first acknowledge the true God. Descartes commented in a reply to one of his objectors that while atheists can clearly be aware of certain propositions that are true, that awareness can not be properly considered knowledge.107 Frederick Schmitt explains that atheists can attain first-order knowledge (cognitio) which results from clear and distinct perception but cannot attain second-order knowledge (scientia) from which doubt has been removed. No cognitio that can be rendered doubtful can be considered scientia. For true knowledge (scientia) requires as its foundation not empirical evidence, but the knowledge of God.108
Existence of material beings. At the outset of Meditation Six, Descartes admits “at least I now know [material things] are capable of existing, in so far as they are the subject-matter of pure mathematics, since I perceive them clearly and distinctly. For there is no doubt that God is capable of creating everything that I am capable of perceiving in this manner.”109 The existence of material reality “is also suggested by the faculty of imagination, which I am aware of using when I turn my mind to material things.”110 Descartes distinguished between imagining and pure understanding: “When the mind understands, it in some way turns towards itself and inspects one of the ideas which are within it; but when it imagines, it turns towards the body and looks at something in the body which conforms to an idea understood by the mind or perceived by the senses.”111 The imagining faculty seems to have as its object not the mind itself, as in pure understanding, but something external to it. If imagining is a legitimate faculty, then it follows that material reality exists.
Restoration of the senses. Recalling from the First Meditation that his external senses occasionally failed him, Descartes adds in the Sixth that the internal senses can also be called into question. Have we not all known of amputees who still “experienced pain” in a limb no longer attached to the body? What better proof could we have that the senses are sometimes unreliable?112 But the sensory doubt that began the Meditations must now be seen in the new light of Cartesian certitude. Descartes now has a better understanding of who he is (a thinking thing) and who his Maker is (the supremely good God), permitting him to concede that “although I do not think I should heedlessly accept everything that I seem to have acquired from the senses, neither do I think that everything should be called into doubt.” 113 This climatic turnabout, the abandonment of the methodic doubt of the senses, is feasible only because he now has clear and distinct principles (the cogito, criterion of truth, existence of God, and explanation of error) by which to judge sensory data. With these new axioms in place, the senses can now finally assume a (mitigated) role in the cognitive process.
Acknowledging the existence of bodies. Once sensory input is accepted (albeit under the watchful eye of the intellect), Descartes can now determine (not discover) just what role the senses play in cognition. In doing so, he recognizes within him two sensory faculties: a “passive faculty of sensory perception, that is, a faculty for receiving and recognizing the ideas of sensible objects…and an active faculty, either in me or in something else, which produced or brought about these ideas.”114 Sensory information comes to him without or even against his will. That is, the senses are a passive faculty. But he could not comprehend the information received by the passive faculty apart from an active faculty. This active faculty could not be in him, the thinking thing, because “the ideas in question are produced without my cooperation and often even against my will.”115 Consequently, Descartes concludes that the faculties of sensory perception must be caused by a body because “[God] has given me a great propensity to believe that they are produced by corporeal things. So I do not understand how God could be understood to be anything but a deceiver if the ideas were transmitted from a source other than corporeal things. It follows that corporeal things exist.”116 Descartes hastens to qualify that not all [the corporeal things] may “exist in a way that exactly corresponds with my sensory grasp of them, for in many cases the grasp of the senses is very obscure and confused. But at least they possess all the properties which I clearly and distinctly understand, that is, all those which, viewed in general terms, are comprised within the subject-matter of pure mathematics.”117 In other words, the senses are still deceptive at times, but at least they teach him “to avoid what induces a feeling of pain and to seek out what induces feelings of pleasure, and so on.”118 But one must not impetuously draw conclusions from sensory input prior to the examination of such input by the far more trustworthy intellect.119
Cartesian dualism. Descartes radically distinguished between the body and soul: “It is true that I may have (or, to anticipate, that I certainly have) a body that is very closely joined to me. But nevertheless, on the one hand I have a clear and distinct idea of myself, in so far as I am simply a thinking, non-extended thing; and on the other hand I have a distinct idea of body, in so far as this is simply an extended, non-thinking thing. And accordingly, it is certain that I am really distinct from my body, and can exist without it.”120 The body is a divisible entity whereas the mind is an indivisible substance. Unlike the Scholastic notion of man as the composition of two incomplete substances, body and soul, united to form a single composite substance, Descartes’ dualism theorizes man as a combination of two complete substances extrinsically accompanying one another.121 The Cartesian soul (mind) is not in the body simply as the captain is in the ship, but rather “the whole mind seems to be united to the whole body.”122 But at the same time, “if a foot or arm or any other part of the body is cut off, nothing has thereby been taken away from the mind.”123 Only the brain, perhaps only a part of the brain known as the common sense, immediately affects the mind.124 Descartes theory of the utter distinction between the divisible, extended, non-thinking body and the indivisible, non-extended, thinking mind is central to his concept of how the sensations of the body interact with the intellect:
For the proper purpose of the sensory perceptions given me by nature is simply to inform the mind of what is beneficial or harmful for the composite of which the mind is a part; and to this extent they are sufficiently clear and distinct. But I misuse them by treating them as reliable touchstones for immediate judgements about the essential nature of the bodies located outside us; yet this is an area where they provide only very obscure information.125
Descartes insists that “notwithstanding the immense goodness of God, the nature of man as a combination of mind and body is such that it is bound to mislead him from time to time.”126 But he is content after all this to trust “that in matters regarding the well-being of the body, all my senses report the truth much more frequently than not.”127
Mitigated empiricism. Because Descartes understood that the promise of scientific advance ultimately depended at least in part on empirical data, he knew he could not altogether abandon the role of the senses.128 Copleston writes that “Descartes’ ‘pan-mathematicism’ is thus not absolute: he does not refuse to allow any role to experience and experiment in physics….[He] recognizes that we cannot in fact dispense with [experience]. But he is far from being an empiricist.”129 What he sought to abandon was what he viewed as the naïve dependence on the senses characteristic of Aristotelianism. By subjecting the senses to universal doubt, methodically applying the first principle of the cogito, and relying heavily on the ontological proofs for the existence of God, Descartes believed he had found mathematical justification for a mitigated trust in the senses. Based on these, he restored to them an epistemological role, albeit subjugated to the more-enlightened and trustworthy intellect guided by clear and distinct principles. Thus, Descartes could conclude the Meditations with a light-hearted sigh of relief:
Accordingly, I should not have any further fears about the falsity of what my senses tell me every day; on the contrary, the exaggerated doubts of the last few days should be dismissed as laughable. This applies especially to the principal reason for doubt, namely my inability to distinguish between being asleep and being awake. For I now notice that there is a vast difference between the two, in that dreams are never linked by memory with all the other actions of life as waking experiences are.130
Popkin observes the immediate resistance that Cartesian epistemology faced: “Those of skeptical inclination…wished to show that he had achieved nothing, and that all his claims were only opinions, not certitudes. So they challenged every advance beyond the cogito, (and even the cogito itself), in order to drown the heroic Descartes in a sink of uncertainty.”131 The Aristotelian traditionalists, on the other hand, claimed that by his method Descartes had created a total skepticism because he rejected the only sources of knowledge, i.e., the senses and the basic principles of reason, by which we can attain indubitable truths.132 The inherent deficiencies of Cartesianism did not go unnoticed by the Catholic Church as they condemned his philosophy in 1663, thirteen years after his death.133 Nevertheless, that Descartes had a major impact on the intellectual world is obvious enough from his designation by many as “the father of modern philosophy.” Descartes’ challenge to Pyrrhonism and Scholasticism ultimately was formidable and successful enough that it begot a whole new Cartesian school of rationalism led by Leibniz, Spinoza, and Malebranche. Indeed, Cartesianism quickly became “the clarion call of the entire early Enlightenment.”134
Regrettably, Cartesian epistemology ultimately gave rise to philosophies with devastating consequences. Mahony says it is “true that philosophy alone, even were it solid and wholesome, could never and will never regenerate the world. But it is equally true that false philosophies will aggravate the tendency in human nature towards degeneracy.”135 Accordingly, he blames the “diseased thought of Descartes” for the rise of materialism, atheism and pantheism in the Western world.136
Gilson notes that “critical idealism was born the day Descartes decided that the mathematical method must henceforth be the method for metaphysics.”137 Thus, “the first consequence of Cartesian mathematicism, and the one from which all the others flow, was the obligation it imposed on the philosopher of always going from thought to being, and even of always defining being in terms of ideas or thought.”138 Once it was decided that knowledge starts in the mind and not in being, “philosophy, after several fruitless attempts to escape from [the mind], declared its final resolve to remain there.”139 Mahony echoes this familiar criticism of Descartes: “It cannot be too often emphasized that, in the theory of knowledge set forth by Descartes, the direct and immediate object both of intellect and sense is not reality as it is in itself apart from, and independent of, the idea of it, but rather ideas themselves. This theory, in the course of time, developed into Idealism.”140 Maritain agrees: “As Luther discovered the Human Person and Jean-Jacques Nature and Liberty, Descartes discovered Thought…. Let us say that Descartes unveiled the face of the monster which modern idealism adores under the name of Thought….[and] what he saw in man’s thought was Independence of Things.”141 With thought now independent of things, man could claim true knowledge only of his idea of reality, not reality itself. Consequently, rather than replacing Scholasticism with an indubitable, mathematical foundation, Rene Descartes’ ironic legacy is that he fathered an irreparable, idealistic epistemology which eventually degenerated into the very skepticism he thought he had conclusively defeated.
[1]Etienne Gilson, Methodic Realism (Front Royal, Virginia: Christendom Press, 1990), 83.
[2]Michael J. Mahony, Cartesianism (New York: Fordham University Press, 1925), 10.
[3]Etienne Gilson, The Unity of Philosophical Experience (Charles Scribner’s Sons, 1937; reprint, San Francisco: Ignatius Press, 1999), 72.
[4]Richard H. Popkin, The History of Scepticism from Erasmus to Descartes, revised edition (New York: Harper Torchbooks, 1968), ix.
[5]Ibid., xi.
[6]Ibid., xii.
[7]Ibid., 13.
[8]Ibid., 84.
[9]Ibid., 179.
[10] Joseph Owens, Cognition: An Epistemological Inquiry (Houston: Center for Thomistic Studies, 1992), 301-302. Owens observes that Cartesianism resulted in theology being excluded from the “domain of rational inquiry.”
[11]Bertrand Russell, A History of Western Philosophy (New York: Simon and Schuster, 1945), 558.
[12]Gary Hatfield, “The Senses and the Fleshless Eye,” in Essays in Descartes’ Meditations, ed. Amelie Oksenberg Rorty (Berkeley: University of California Press, 1986), 54.
[13]Norman L. Geisler, Christian Apologetics (Grand Rapids: Baker Books, 1976) 31-32.
[14]Rene Descartes, Discourse on the Method: A Bilingual Edition with an Interpretive Essay, trans. George Heffernan (Notre Dame: University of Notre Dame Press, 1994), 127.
[15]Descartes, Discourse, 17.
[16]John P. Carriero, “The Second Meditation and the Essence of the Mind,” in Essays, 209.
[17]Descartes, Discourse, 23.
[18]Ibid., 21.
[19]Ibid.
[20]Gilson, Unity, 114.
[21]Jacques Maritain, Three Reformers: Luther-Descartes-Rousseau (London: Sheed & Ward, 1936), 64, 75.
[22]Frederick Copleston, A History of Philosophy, vol. 4, Modern Philosophy: From Descartes to Leibniz (New York: Image Books, 1994), 70.
[23]See Daniel Garber, “semel in vita: The Scientific Background to Descartes’ Meditations,” in Essays, 108.
[24]Gilson, Unity, 100, 110.
[25]Descartes, Discourse, 47.
[26]Owens, 8.
[27]Copleston, 85.
[28]Ibid.
[29]Carriero, in Essays, 200-203.
[30]Hatfield, in Essays, 46.
[31]Descartes, Discourse, 57. For a brief rebuttal see Owens, 60.
[32]Garber, in Essays, 89-91.
[33]Rene Descartes, Meditations on First Philosophy: With Selections from the Objections and Replies, trans. John Cottingham (Cambridge: Cambridge University Press, 1996), 12.
[34]Ibid., 13.
[35]Ibid.
[36]Ibid., 65-66.
[37]Ibid., 14.
[38]Ibid.
[39]Ibid.
[40]Ibid., 15. see Popkin, 185, for discussion of possible source of demon hypothesis.
[41]E. M. Curley, “Analysis in the Meditations,” in Essays, 169. Descartes argued for divine simplicity in the Third Meditation (p.34) and claimed in the Fourth (p.46) that God “cannot be a deceiver on pain of contradiction.”
[42]Mahony, 34.
[43]Descartes, Meditations, 15. Mahony, 34-36, conjectures that Descartes’ methodic doubt would also discard testimony and historical witness for the same reasons he doubts the senses and first principles.
[44]Descartes, Meditations, 16.
[45]Ibid., 17.
[46]Genevieve Rodis-Lewis, “On the Complementarity of Meditations III and V,” in Essays, 280.
[47]Norman Geisler, Baker Encyclopedia of Christian Apologetics (Grand Rapids: Baker Books, 1999), 194.
[48]Gilson, Unity, 123-125. see also Mahony, 45 and Russell, 564.
[49]Mahony, 48.
[50]Carriero, in Essays, 208.
[51]Descartes, Meditations, 17-18. Descartes defined body as “whatever has a determinable shape and a definable location and can occupy a space in such a way as to exclude any other body; it can be perceived by touch, sight, hearing, taste or smell, and can be moved in various ways, not by itself but by whatever else comes in contact with it.”
[52]Ibid., 18.
[53]Ibid., 19.
[54]See Gilson, Unity, 129.
[55]Descartes, Meditations, 72. (emphasis added)
[56]Ibid., 20.
[57]Ibid., 21. see also Garber, in Essays, 100.
[58]Ibid., 21-23.
[59]Carriero, in Essays, 205.
[60]Descartes, Meditations, 24.
[61]Geisler, BECA, 195.
[62]Mahony, 50.
[63]Copleston, 98.
[64]Popkin, 190.
[65]Descartes, Meditations, 25-26.
[66]Ibid., 26.
[67]Ibid., 27.
[68]Ibid.
[69]Maritain, 56.
[70]Ibid., 66-67.
[71]Ibid., 77.
[72]Ibid., 82.
[73]Some interpreters of Descartes point out that Plato’s Forms, firmly lodged in the mind of God by the time of Augustine, are replaced by the Cartesian theory of innate ideas. See Hatfield, in Essays, 65 and Calvin Normore, “Meaning and Objective Being,” in Essays, 231.
[74]Geisler, Christian Apologetics, 29.
[75]Ibid.
[76]Ibid., 29-30.
[77]Descartes, Meditations, 28.
[78]Ibid., 29.
[79]Ibid.
[80]Ibid., 29-30.
[81]Ibid., 31.
[82]Ibid.
[83]Ibid.
[84]Geisler, Christian Apologetics, 30-31.
[85]Gilson, Unity, 142.
[86]Ibid., 144.
[87]Descartes, Meditations, 34.
[88]Ibid.
[89]Ibid., 35.
[90]Ibid., 37.
[91]Ibid., 37-38.
[92]Ibid., 39.
[93]Ibid., 40.
[94]Ibid., 39.
[95]Ibid. Also worthy of mention is Descartes’ voluntarism (see Meditations, 93). The three angles of a triangle are equal to two right angles because God willed it so. The innate ideas, or eternal truths, are what they are because God willed them that way. The world of reason need not be what it is. God willed, for example, that 1 + 2 = 3, but could have willed otherwise. (see Hide Ishiguro, “The Status of Necessity and Impossibility,” in Essays, 461-467.)
[96]Ibid., 40-41.
[97]Ibid.
[98]Martha Bolton, “Confused and Obscure Ideas of Sense,” in Essays, 389.
[99]Maritain, 60-61.
[100]Descartes, Meditations, 41.
[101]Ibid., 44.
[102]Ibid., 46.
[103]Ibid.
[104]Ibid., 45.
[105]Popkin, 192.
[106]Descartes, Meditations, 49.
[107]Ibid., 103.
[108]Frederick F. Schmitt, “Why was Descartes a Foundationalist?” in Essays, 501-502.
[109]Descartes, Meditations, 50.
[110]Ibid.
[111]Ibid., 51.
[112]Ibid.
[113]Ibid., 54. Emphasis added.
[114]Ibid., 55.
[115]Ibid. Descartes (p. 59) considered the it “the same mind that wills, and understands and has sensory perceptions.” Therefore, since the mind is indivisible, it cannot be in conflict with itself.
[116]Ibid.
[117]Ibid.
[118]Ibid., 57.
[119]Ibid.
[120]Ibid., 54.
[121]Mahony, 56.
[122]Descartes, Meditations, 59.
[123]Ibid.
[124]Ibid. Cottingham explains in footnote 1 on pg. 59 that the common sense, seated in the pineal gland, is the faculty that integrates the data of the five specialized senses.
[125]Ibid., 57-58.
[126]Ibid., 61.
[127]Ibid.
[128]see Hatfield, in Essays, 56.
[129]Copleston, 82.
[130]Descartes, Meditations, 61.
[131]Popkin, 197.
[132]Ibid., 202.
[133]Heffernan, in Discourse, 220.
[134]Ibid., 162. See also Gilson, Unity, 148.
[135]Mahony, 23.
[136]Ibid.
[137]Gilson, Methodical Realism, 18.
[138]Ibid., 84.
[139]Ibid., 90.
[140]Mahony, 63.
[141]Maritain, 54-55.