Rene Descartes (1596-1650) is one of the most important figures in the history of philosophy. Many of his ideas—for instance, his demand for a foundation of the sciences on an apodictic principle; his use of mathematics as a paradigm for natural science; his concept of science as a systematic totality; and his first principle of all philosophy, the famous cogito, ergo sum (“I think, therefore I am”)—deeply influenced Western European philosophical and scientific thought. At the same time, Descartes articulated some general problems still contentious in today’s philosophical discussions, such as the problem of body and soul, the irreducibility of the first-person perspective, and the problem of the existence of an external world. Descartes also earned much criticism for his dualist conception of human beings as consisting of two real, distinct substances (body and mind/soul) and his mechanistic model of the (animated) body.
Rene Descartes was born in 1596 in La Haye (today called Descartes), a village near Tours, France. Between 1606 and 1614 he was educated in the Jesuit College of La Fleche. Although this college was grounded on scholastic tradition, especially the philosophy of Aristotle, Saint Thomas Aquinas, and Francisco Suarez, it did not ignore the study of (natural) science. Descartes also came into contact with the works of ancient mathematicians, such as Pappus and Euclid. Deeply inspired by the validity and evidence of mathematical proof, Descartes became dissatisfied with natural philosophy based on Aristotelian principles, such as the doctrine of substantial forms and self-motion of animated bodies as being caused by their souls. He also disagreed with a foundation of philosophy on theological principles and stressed the necessity of a separation of reason and faith.
After his time in La Fleche, Descartes studied law in Poitiers. In 1618 he enlisted in the Dutch, and later in the Bavarian, army. One year later, Descartes became acquainted with Isaak Beeckman, a Dutch scientist and mathematician, under whose influence he began working on mathematical studies of natural phenomena. Between 1619 and 1629, Descartes traveled widely and also frequented a circle of mathematicians and physicists gathered around Father Merin Mersenne in Paris. From 1629 on, Descartes lived in different domiciles in Holland for about 20 years. During this time, Descartes was working on optical, meteorological, and geometrical issues. At the same time, his concern was to find the final principles of the sciences and philosophy. In 1637 Descartes published his Discours de la methode (Discourse on Method); 4 years later his famous Meditationes de prima philosophia (Meditations on First Philosophy) appeared. The Principia philosophiae (Principles of Philosophy), Descartes’ second main work, followed in 1644; his final work, the Les passions de l’âme (Passions of the Soul), was published in 1649. In the same year Descartes moved to Stockholm at the invitation of Queen Christina of Sweden, who employed him as philosophical and mathematical tutor. He died in 1650.
The Concept of Time in Descartes’ Works
At first sight, the concept of time does not seem to play an important role in Descartes’ thought. In both his major works, the Meditations on First Philosophy (Med.) and the Principles of Philosophy (PP), time seems to be of little interest. In Med. III Descartes discusses the natura temporis (nature of time) in a very short passage as a supporting argument for his first proof of God’s existence; in the PP time merely serves as an illustration for general epistemological and ontological problems. At second sight, however, the issue is far more complicated. Although the singular passage in Med. III discussing the concept of time seems to be marginal because of its shortness, it nevertheless marks the zenith of the whole proof of God’s existence; in the PP, the concepts of time and duration show an irritating ambiguity. The following sections discuss Descartes’ reflection about time in the Meditations and provide an outline of Descartes’ definitions of time and duration in the Principles of Philosophy.
Time in the Meditations
Descartes’ aim in the Meditations is to establish certain and indubitable knowledge. For this purpose he starts scrutinizing the validity of the opinions he formerly had believed to be true. Descartes does not try to prove his opinions to be false; it is enough for him to show their doubtfulness, since “my reason convinces me that I ought not the less carefully to withhold belief from what is not entirely certain and indubitable, than from what is manifestly false, it will be sufficient to justify the rejection of the whole if I shall find in each some ground for doubt” (Med. I 1). Sensual perception soon appears to be no candidate for indubitable truth; first, the senses “occasionally mislead us respecting minute objects” (Med. I 4); second, Descartes perceives “clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep” (Med. I 5). In a third step, Descartes doubts the validity of rational and mathematical insight by constructing the concept of a “malignant demon [genius malignus] who is at once exceedingly potent and deceitful” and “has employed all his artifice to deceive me” (Med. I 12). However, although the result of the First Meditation seems to be “that there is nothing certain” (Med. II 1), in the Second Meditation Descartes soon finds “one thing that is certain and indubitable” (Med. II 1), namely, the fact of his own existence:
Doubtless, . . . I exist, since I am deceived; and, let him [sc. the malignant demon] deceive me as he may, he can never bring it about that I am nothing, so long as I shall be conscious that I am something [quamdiu me aliquid esse cogitabo]. So that it must, in fine, be maintained, all things being maturely and carefully considered, that this proposition I am, I exist, is necessarily true each time it is expressed by me, or conceived in my mind. (Med. II 3)
An investigation of the question “what I am” and the consideration that the existence of bodies is dubitable—since bodies are the objects of sensual perception that has been doubted in Med. I—brings out the conclusion that all Descartes can be absolutely certain of is to be “a thinking thing [res cogitans]. . . . But what is a thinking thing? It is a thing that doubts, understands, [conceives], affirms, denies, wills, refuses; that imagines also, and perceives” (Med. II 9). In other words, Descartes cannot be certain whether the objects of his acts of consciousness, including his own body, exist independently of these acts, but he nevertheless can be certain that these mental acts themselves and he as the “thing” (res cogitans, mind [mens]) in which they are produced exist. The aim of the following Third Meditation is to transcend this solipsist perspective by working out the basics for the proof of an external world. This, however, cannot be done unless God’s existence and truthfulness are demonstrated: “I must inquire whether there is a God, as soon as an opportunity of doing so shall present itself; and if I find that there is a God, I must examine likewise whether he can be a deceiver; for, without the knowledge of these two truths, I do not see that I can ever be certain of anything” (Med. III 4). For this purpose, Descartes analyzes the idea of God by focusing on two aspects: first, whether Descartes himself as a finite thinking substance could be the cause for this idea’s existence within his mind; second, whether there is a need to ask for a cause for this idea’s existence at all. The concept of time plays a crucial role in Descartes’ discussion of the second question.
Descartes starts with a definition of God: “By the name God, I understand a substance infinite, [eternal, immutable], independent, all-knowing, all-powerful, and by which I myself, and every other thing that exists, if any such there be, were created” (Med. III 22). As a finite substance, Descartes argues, he cannot be the cause of the infinity involved in the idea of God. “For though the idea of substance be in my mind owing to this, that I myself am a substance, I should not, however, have the idea of an infinite substance, seeing I am a finite being, unless it were given me by some substance in reality infinite” (Med. III 23). Descartes also denies that God’s infinity and perfection could be set within himself potentially, “for . . . although it were true that my knowledge daily acquired new degrees of perfection, and although there were potentially in my nature much that was not as yet actually in it, still all these excellences make not the slightest approach to the idea I have of the Deity, in whom there is no perfection merely potentially [but all actually] existent” (Med. III 27). In addition, Descartes argues that it is impossible to interpret the infinity and perfection involved in the idea of God as mere abstract negations of his (i.e., Descartes’) finitude and imperfection. Nevertheless it is still possible that the divine features of God’s idea do not require a cause for existing in Descartes’ mind. Thus, Descartes asks himself “whether I, who possess this idea of God, could exist supposing there were no God” (Med. III 28). In this case, either Descartes was the cause of his own existence or there was no cause for his existence at all. Descartes tries to demonstrate the impossibility of both suggestions by discussing the nature of time:
And though I were to suppose that I always was as I now am, I should not, on this ground, escape the force of these reasonings, since it would not follow, even on this supposition, that no author of my existence needed to be sought after. For the whole time of my life may be divided into an infinity of parts, each of which is in no way dependent on any other; and, accordingly, because I was in existence a short time ago, it does not follow that I must now exist, unless in this moment some cause create me anew as it were, that is, conserve me. In truth, it is perfectly clear and evident to all who will attentively consider the nature of time [natura temporis], that the conservation of a substance, in each moment of its duration, requires the same power and act that would be necessary to create it, supposing it were not yet in existence; so that it is manifestly a dictate of the natural light that conservation and creation differ merely in respect of our mode of thinking [and not in reality]. (Med. III 31)
The temporality of the “I” thus involves the metaphysical dependence of the finite self from an infinite cause, that is, God. Because time has no intrinsic continuity but appears as a series of relatively independent moments, any continuity of duration calls for a cause; and since continuity is equivalent with permanent creation, which needs a power that Descartes cannot find within his own existence, only God can be the cause for the permanent being of the “I.” Thus, according to Descartes the mere fact of one’s own temporal existence immediately indicates the existence of God in a way that knowledge of myself involves knowledge of God:
When I make myself the object of reflection, I not only find that I am an incomplete, [imperfect] and dependent being, and one who unceasingly aspires after something better and greater than he is; but, at the same time, I am assured likewise that he upon whom I am dependent possesses in himself all the goods after which I aspire [and the ideas of which I find in my mind], and that not merely indefinitely and potentially, but infinitely and actually, and that he is thus God. (Med. III 38)
“Time” in the Principles of Philosophy
In the Principles of Philosophy Descartes takes a more objective perspective on time and duration. However, he seems to be irresolute where time and duration have to be located in ontological terms. He states: “Whatever objects fall under our knowledge we consider either as things or the affections of things, or as eternal truths possessing no existence beyond our thought. Of the first class the most general are substance, duration, order, number, and perhaps also some others, which notions apply to all the kinds of things” (PP I 48). “Duration” here seems to be a “thing” (res) just as a body or a mind. A few pages farther, however, the concept of duration is denied to designate a thing; it is merely the name for a mode (accident):
We will also have most distinct conceptions of duration, order, and number, if, in place of mixing up with our notions of them that which properly belongs to the concept of substance, we merely think that the duration of a thing is a mode under which we conceive this thing, in so far as it continues to exist; and, in like manner, that order and number are not in reality different from things disposed in order and numbered, but only modes under which we diversely consider these things. (PP I 55)
Again the situation changes when Descartes discusses the relation of time and duration. Now duration seems to be something in the thing (substance) itself, while time now appears to be a mere mode of our thinking:
Of these attributes or modes there are some which exist in the things themselves, and others that have only an existence in our thought; thus, for example, time, which we distinguish from duration taken in its generality, and call the measure of motion, is only a certain mode under which we think duration itself . . . [;] that we may comprehend the duration of all things under a common measure, we compare their duration with that of the greatest and most regular motions that give rise to years and days, and which we call time; hence what is so designated is nothing superadded to duration, taken in its generality, but a mode of thinking. (PP I 57)
While time is nothing but a measure of comparing the durations of things and thus a mode of our thought, not of the things themselves, duration itself cannot be separated from the enduring thing unless by abstraction—that is, as a mode of our thought: “For example, because any substance which ceases to endure ceases also to exist, duration is not distinct from substance except in thought (ratione)” (PP I 62). Descartes’ indecision about the ontological and metaphysical location of time and duration results from a fundamental ambivalence of the Cartesian concept of substance, as the term substance can indicate one individual being among others of the same genus (e.g., one singular body) as well as the genus itself (e.g., “the extended substance” in the sense of “extension as such”).
Descartes’ concept of time and duration as a discontinuous series of moments and the temporal vagueness of the sum (“I am”) has been extensively discussed and critiqued by other philosophers, in the 20th century perhaps most notably by Martin Heidegger.
Marko J. Fuchs
See also Aristotle; Augustine of Hippo, Saint; Duration; Epistemology; Heidegger, Martin; Kant, Immanuel; Metaphysics; Ontology; Solipsism; Spinoza, Baruch de; Time, Measurements of
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