Veleentabel van Descartes (1596 - 1650)

Gemaakt op 14 November 1989 met computerprogramma van CAVESOFT (H.D. Kuilman) in GW-Basic.

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plato.stanford.edu/entries/descartes/#MetTurComPhyDis

 

1.3 Metaphysical turn, comprehensive physics, Discourse

 

Upon arriving in the Netherlands, Descartes undertook work on two sorts of topics. In Summer, 1629, an impressive set of parhelia, or false suns, were observed near Rome. When Descartes heard of them, he set out to find an explanation. (He ultimately hypothesized that a large, solid ice-ring in the sky acts as a lens to form multiple images of the sun [6:355].) This work interrupted his investigations on another topic, which had engaged him for his first nine months in the Netherlands (1:44)—the topic of metaphysics, that is, the theory of the first principles of everything that there is. The metaphysical objects of investigation included the existence and nature of God and the soul (1:144, 182). However, these metaphysical investigations were not entirely divorced from problems such as the parhelia, for he claimed that through his investigations into God and the human self, he had been able “to discover the foundation of physics” (1:144). Subsequently, Descartes mentioned a little metaphysical treatise in Latin—presumably an early version of the Meditations—that he wrote upon first coming to the Netherlands (1:184, 350). And we know that Descartes later confided to Mersenne that the Meditations contained “all the principles of my physics” (3:233).

 

While working on the parhelia, Descartes conceived the idea for a very ambitious treatise. He wrote to Mersenne that he had decided not to explain “just one phenomenon” (the parhelia), but rather to compose a treatise in which he explained “all the phenomena of nature, that is to say, the whole of physics” (1:70). This work eventually became The World, which was to have had three parts: on light (a general treatise on visible, or material, nature), on man (a treatise of physiology), and on the soul. Only the first two survive (and perhaps only they were ever written), as the Treatise on Light and Treatise on Man. In these works, which Descartes decided to suppress upon learning of the condemnation of Galileo (1:270, 305), he offered a comprehensive vision of the universe as constituted from a bare form of matter having only length, breadth, and depth (three-dimensional volume) and carved up into particles with size and shape, which may be in motion or at rest, and which interact through laws of motion enforced by God (11:33–4). These works contained a description of the visible universe as a single physical system in which all its operations, from the formation of planets and the transmission of light from the sun, to the physiological processes of human and nonhuman animal bodies, can be explained through the mechanism of matter arranged into shapes and structures and moving according to three laws of motion. In fact, his explanations in the World and the subsequent Principles made little use of the three laws of motion in other than a qualitative manner. The laws sustained the notion that matter moves regularly (in a straight line) and that upon impact bits of matter alter their motions in regular ways—something that happens constantly in the full universe (the “plenum”) conceived by Descartes.

 

After suppressing his World, Descartes decided to put forward, anonymously, a limited sample of his new philosophy, in the Discourse with its attached essays. The Discourse recounted Descartes' own life journey, explaining how he had come to the position of doubting his previous knowledge and seeking to begin afresh. It offered some initial results of his metaphysical investigations, including mind–body dualism. It did not, however, engage in the deep skepticism of the later Meditations, nor did it claim to establish, metaphysically, that the essence of matter is extension. This last conclusion was presented merely as a hypothesis whose fruitfulness could be tested and proven by way of its results, as contained in the attached essays on Dioptrics and Meteorology. The latter subject area comprised “atmospheric” phenomena. In his Meteorology, Descartes described his general hypothesis about the nature of matter, before continuing on to provide accounts of vapors, salt, winds, clouds, snow, rain, hail, lightning, the rainbow, coronas, and parhelia.

 

Descartes wrote in the Meteorology that he was working from the following “supposition” or hypothesis: “that the water, earth, air, and all other such bodies that surround us are composed of many small parts of various shapes and sizes, which are never so properly disposed nor so exactly joined together that there do not remain many intervals around them; and that these intervals are not empty but are filled with that extremely subtle matter through the mediation of which, I have said above, the action of light is communicated” (6:233). He presented a corpuscularian basis for his physics, which denied the atoms-and-void theory of ancient atomism and affirmed that all bodies are composed from one type of matter, which is infinitely divisible (6:239). In the World, he had presented his non-atomistic corpuscularism, but without denying void space outright and without affirming infinite divisibility (11:12–20).

 

In the Meteorology, he also proclaimed that his natural philosophy had no need for the “substantial forms” and “real qualities” that other philosophers “imagine to be in bodies” (6:239). He had taken the same position in the World, where he said that in conceiving his new “world” (i.e., his conception of the universe), “I do not use the qualities called heat, cold, moistness, and dryness, as the Philosophers do” (11:25). Indeed, Descartes claimed that he could explain these qualities themselves through matter in motion (11:26), a claim that he repeated in the Meteorology (6:235–6). In effect, he was denying the then-dominant scholastic Aristotelian ontology, which explained all natural bodies as comprised of a “prime matter” informed by a “substantial form,” and which explained qualities such as hot and cold as really inhering in bodies in a way that is “similar” to the qualities of hot and cold as we experience them tactually.

 

Unlike Descartes' purely extended matter, which can exist on its own having only size and shape, many scholastic Aristotelians held that prime matter cannot exist on its own. To form a substance, or something that can exist by itself, prime matter must be “informed” by a substantial form (a form that renders something into a substance). The four Aristotelian elements, earth, air, fire, and water, had substantial forms that combined the basic qualities of hot, cold, wet, and dry: earth is cold and dry; air is hot and wet; fire is hot and dry; and water is cold and wet. These elements can themselves then serve as “matter” to higher substantial forms, such as the form of a mineral, or a magnet, or a living thing. Whether in the case of earth or of a living rabbit, the “form” of a thing directs its characteristic activity. For earth, that activity is to approach the center to the universe; water has the same tendency, but not as strongly. For this reason, Aristotelians explained, the planet earth has formed at the center, with water on its surface. A new rabbit is formed when a male rabbit contributes, through its seed-matter, the “form” of rabbithood to the seed-matter of the female rabbit. This form then organizes that matter into the shape of a rabbit, including organizing and directing the activity of its various organs and physiological processes. The newborn rabbit's behavior is then guided by its rabbit-specific “sensitive soul,” which is the name for the substantial form of the rabbit. Other properties of the rabbit, such as the whiteness of its fur, are explained by the “real quality” of white inhering in each strand of hair.

 

Although in the World and Meteorology Descartes avoided outright denial of substantial forms and real qualities, it is clear that he intended to deny them (1:324; 2:200; 3:420, 500, 648). Two considerations help explain his tentative language: first, when he wrote these works, he was not yet prepared to release his metaphysics, which would support his hypothesis about matter and so rule out substantial forms (1:563); and, second, he was sensitive to the prudential value of not directly attacking the scholastic Aristotelian position (3:298), since it was the accepted position in university education (3:577) and was strongly supported by orthodox theologians, both Catholic and Protestant (1:85–6; 3:349).

 

After publication of the Discourse in 1637, Descartes received in his correspondence queries and challenges to various of the doctrines, including his account of the sequence of phenomena during heart-beat and the circulation of the blood; his avoidance of substantial forms and real qualities; his argument for a distinction between mind and body; and his view that natural philosophical hypotheses could be “proven” through the effects that they explain (6:76). Descartes' correspondence from the second half of the 1630s repays close study, among other things for his discussions of hypothesis-confirmation in science, his replies to objections concerning his metaphysics, and his explanation that he had left the most radical skeptical arguments out of this work, since it was written in French for a wide audience (1:350, 561).

 

In 1635, Descartes fathered a daughter named Francine. Her mother was Descartes' housekeeper, Helena Jans. They lived with Descartes part of the time in the latter 1630s, and Descartes was arranging for them to join him when he learned of Francine's untimely death in September 1640. Descartes subsequently contributed a dowry for Helena's marriage in 1644 (Watson 2007, 188).

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In the course of the Third Meditation, Descartes constructs an argument for the existence of God that starts from the fact that he has an idea of an infinite being. The argument is intricate. It invokes the metaphysical principle that “there must be at least as much reality in the efficient and total cause as in the effect of that cause” (7:40). This principle is put forward as something that is “manifest by the natural light” (7:40), which itself is described as a cognitive power whose results are indubitable (7:38), like clear and distinct perception (7:144). Descartes then applies that principle not to the mere existence of the idea of God as a state of mind, but to the content of that idea. Descartes characterizes that content as infinite, and he then argues that a content that represents infinity requires an infinite being as its cause. He concludes, therefore, that an infinite being, or God, must exist. He then equates an infinite being with a perfect being and asks whether a perfect being could be a deceiver. He concludes: “It is clear enough from this that he cannot be a deceiver, since it is manifest by the natural light that all fraud and deception depend on some defect” (7:52).

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In the textbooks of Aristotelian physics of Descartes' day, it was common to divide physics into “general” and “special.” General physics pertained to the basic Aristotelian principles for analyzing natural substances: form, matter, privation, cause, place, time, motion. Special physics concerned actually existing natural entities, divided into inanimate and animate. Inanimate physics further divided into celestial and terrestrial, in accordance with the Aristotelian belief that the earth was at the center of the universe, and that the earth was of a different nature than the heavens (including the moon, and everything beyond it). Inanimate terrestrial physics first covered the four elements (earth, air, fire, and water), then the “mixed” bodies composed from them, including the various mineral kinds. Animate terrestrial physics concerned the various powers that Aristotelians ascribed to ensouled beings, where the soul is considered as a principle of life (possessing vital as well as mental or cognitive powers). In the simplest textbooks, the powers of the soul were divided into three groups: vegetative (including nutrition, growth, and reproduction), which pertained to both plants and animals; sensitive (including external senses, internal senses, appetite, and motion), which pertain to animals alone; and rational powers, pertaining to human beings alone. All the bodies in both inanimate and animate terrestrial physics were governed by a “form” or active principle, as described in Section 1.3.

 

Descartes' ambition was to provide replacements for all the main parts of Aristotelian physics. In his physics, there is only one matter and it has no active forms. Thus, he dissolved the boundary that had made the celestial and the terrestrial differ in kind. His one matter had only the properties of size, shape, position, and motion. The matter is infinitely divisible and it constitutes space; there is no void, hence no spatial container distinct from matter. The motions of matter are governed by three laws of motion, including a precursor to Newton's law of inertia (but without the notion of vector forces) and a law of impact. Descartes' matter possessed no “force” or active agency; the laws of motion were decreed by God and were sustained by his activity. Earth, air, fire, and water were simply four among many natural kinds, all distinguished simply by the characteristic sizes, shapes, positions, and motions of their parts.

 

Although Descartes nominally subscribed to the biblical story of creation, in his natural philosophy he presented the hypothesis that the universe began as a chaotic soup of particles in motion and that everything else was subsequently formed as a result of patterns that developed within this moving matter. Thus, he conceived that many suns formed, around which planets coalesced. On these planets, mountains and seas formed, as did metals, magnets, and atmospheric phenomena such as clouds and rain. The planets themselves are carried around the sun in their orbits by a fluid medium that rotates like a whirlpool or vortex. Objects fall to earth not because of any intrinsic “form” that directs them to the center of the universe, and also not because of a force of attraction or other downward-tending force. Rather, they are driven down by the whirling particles of the surrounding ether. Descartes insisted that all cases of apparent action at a distance, including magnetism, must be explained through the contact of particle on particle. He explained magnetism as the result of corkscrew-shaped particles that spew forth from the poles of the earth and flow from north to south or vice versa, causing magnetized needles to align with their flow (Princ. IV.133–83). To explain magnetic polarity, Descartes posited that the particles exiting from the south pole are threaded in one direction and those from the north are threaded oppositely (like the oppositely threaded spindles on bicycle pedals).

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