1 The Meditations leave no doubt as to the fact that
Descartes
ac cepted the conception of God quite in accordance with the inter
pretation of scholastic Realism.
pretation of scholastic Realism.
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Chap. 2, $ 30. ] Problem of Method : Spinoza, Leibniz. 397
inferences. Especially did the mathematically schooled Cartesians in Germany take up the geometrical method along this line : this was done by Jung and Weigel, and the academic impulse to the preparation of text-books found in this method a form with which it could have the utmost sympathy. In the eighteenth cen tury Christian Wolff (cf. Part V. ) pursued this line in the most comprehensive manner with his Latin text-books, and for the sys- tematisation of a firmly established and clearly thought out material there could be in fact no better form. This was shown when Puffen-
dorf undertook to deduce the entire system of Natural Right by the geometrical method, as a logical necessity from the single principle of the need of society.
When this view was in process of coming into existence Leibniz came into sympathy with it under the especial influence of Erhard Weigel, and was at the beginning one of its most consistent sup
He not only made the jest of giving this unwonted garb to a political brochure,1 but was seriously of the opinion that philo sophical controversies would find their end for the first time when a philosophy could once make its appearance in as clear and certain a form as that of a mathematical calculation. *
Leibniz pursued this thought very energetically. The stimulus of Hobbes, who also — though with quite another purpose, cf. § 31, 2 — declared thinking to be a reckoning with the conceptional signs of things, may have been added ; the Art of Lull and the pains which Giordano Bruno had taken with its improvement were well known to him. In Cartesian circles, also, the thought of transform ing the mathematical method to a regular art of invention had been
much discussed : besides Joachim Jung, the Altorf Professor Joh. Christopher Sturm,3 had also exercised an influence upon Leibniz in this respect. Finally, the thought of expressing the fundamental metaphysical conceptions, and likewise the logical operations of their combination after the manner of the mathematical sign-lan guage by definite characters, seemed to offer the possibility of writ ing a philosophical investigation in general formula1, and by this means raising it beyond the capability of being expressed in a
definite language — an effort toward a universally scientific lan guage, a " Lingua Adamica," which likewise appeared at the time
* In the pseudonymous Specimen drmonMratinnum politieanim pro rr<>r Polo- norum tligendo (MW9), he proved by "geometrical mt-tliod" in sixty proposi tions and demonstration* that the Count Palatine of Neuhiiix imutt be chosen king of the Pole*. -^
* De Srlrntin Vmvertali ten Calrulo Phllotophico (U>«4). ' * The author of a Compendium Univrrtalium sen Metaphyiicu KurlUIn*
regular
porters.
The Renaissance : Natural Science Period. [Part IV.
of Leibniz in numerous supporters. 1 So, too, Leibniz busied himself to an extraordinary degree with the thought of a characteristica uni versalis, and a method of philosophical calculus. 2
The essential outcome of these strange endeavours was, that an attempt was necessarily made to establish those highest truths, from the logical combination of which all knowledge was to be deduced. So Leibniz, like Galileo and Descartes, must proceed to search out that which, as immediately and intuitively certain, forces itself upon the mind as self-evident, and by its combinations grounds all derived knowledge. In the course of these reflections Leibniz stumbled upon the discovery3 (which Aristotle had made before him), that there are two completely different kinds of this intuitive knowledge : universal truths self-evident to reason, and facts of experience. The one class has timeless validity ; the other, validity for a single instance : viritis iternelles and vtrite's de fait. Both have in common that they are intuitively certain, i. e. are certain in them selves and not by deduction from anything else ; they are called, therefore, prima veritates, or, also, primes possibiiitates, because in them the possibility of all that is derivative has its ground. For the " possibility " of a conception is known either by a " causal definition " which derives the same from the first possibilities, that is, a priori; or by the immediate experience of its actual existence, that is, a, posteriori.
These two kinds of "primitive truths" — the rational and the empirical, as we see — Leibniz attached in a very interesting manner to the two Cartesian marks of intuitive self-evidence, clearness and distinctness. To this end he shifts to a slight extent the meaning of both expressions. 4 That idea is clear which is surely distin guished from all others and so is adequate for the recognition of its object; that idea is distinct which is clear even to its particular constituent parts and to the knowledge of their combination. According to this, the a priori, "geometrical" or "metaphysical" eternal truths are clear and distinct ; while on the other hand the a posteriori, or the truths relating to facts, are clear, indeed, but not distinct. Hence the former are perfectly transparent, conjoined with the conviction of the impossriblity of the opposite, while in the case of the latter the opposite is thinkable. In the case of the former the intuitive certainty rests upon the Principle of Contradic
1 Such attempts had been projected by J. J. Becker (1661 ), G. Dalgarn (1661), Athanasius Kircher (1663), and J. Wilkins ( 1668).
* Cf. A. Trendelenburg, Historische Beitrage zu Philosophic, Vols. II. , III. 8 Meditationes de Cognitions Veritute et Idris (1684).
* lb. at the beginning, Erd's. ed. , p. 79.
Chap. 2, § 31. ] Substance and Causality. 399
twn; in the case of the latter the possibility guaranteed by the actual fact needs still an explanation in accordance with the Prin
ciple of Sufficient Reason.
At the beginning, Leibniz intended this distinction only with
reference to the imperfection of the human understanding. In the case of rational truths we see into the impossibility of the opposite ; with empirical truths this is not the case, and we must content our selves with establishing their actuality : ' but the latter also, in the natura rerum and for the divine understanding, are so grounded that the opposite is impossible, although it remains thinkable for us. If Leibniz compared this distinction with that of commensur able and incommensurable magnitudes, he meant at the beginning that incommensurability lies only in man's limited knowing capacity. But in the course of his development this antithesis became for him an absolute one ; it gained metaphysical significance. Leibniz now distinguished realiter between an unconditional necessity, which involves the logical impossibility of the opposite, and a conditional necessity, which has " only " the character of a matter of fact. He divided the principles of things into those of which the opposite is unthinkable, and those of which the opposite is thinkable : he dis tinguished metaphysically, also, between necessary and contingent truths. This, however, cohered with metaphysical motives, which arose from an after-working of the Scotist theory of the contin gency of the finite, and overthrew the geometrical method.
§ 31. Substance and Causality.
The real [as contrasted with formal] result of the new methods was in metaphysics, as in natural science, a transformation of the fundamental ideas of the nature of things, and of the mode of their connection in the processes of Nature : the conceptions of sub stance and causality acquired a new content. Hut this change could not proceed so radically in metaphysics as in natural science. In this latter more limited realm, after the Galilean principle had once been found, it was possible in a certain measure to begin ab ovo and produce a completely new theory : in the more general philo sophical doctrines the power and authority of tradition were much too great to make it possible or permissible that it should be completely set aside.
This distinction asserted itself already in connection with the delicate relation sustained to religious conceptions. Natural science
1 The Aristotelian distinction of Mti and An,
400 The Renaissance : Natural Science Period. (Taet IV.
could isolate itself absolutely from theology, and maintain toward it an attitude of complete indifference : metaphysics, by its concep tion of the deity and by its theory of the mental or spiritual world, was brought again and again into hostile or friendly contact with the religious sphere of ideas. A Galileo declared that the investigations of physics, whatever their result might be, had not the least thing to do with the teaching of the Bible,1 and a Newton was not prevented by his mathematical natural philosophy from burying himself with the most ardent piety in the mysteries of the Apocalypse. But the metaphysicians, however indifferent their thought as regards religion, and however strictly they might prose cute their science in the purely theoretical spirit, were still always obliged to consider that they had to do with objects concerning which the Church doctrine was fixed. This gave modern philosophy a somewhat delicate position : mediaeval philosophy had brought to the objects of Church dogma an essentially religious interest of its own as well ; modern philosophy regarded them, if at all, from the theoretical standpoint only. Hence those felt themselves most secure who, like Bacon and Hobbes, restricted philosophy also entirely to natural research, declined to enter upon a metaphysics proper, and were willing to let dogma speak the only words with regard to the deity and the super-sensible destiny of man. Bacon did this with large words behind which it is difficult to recognise his true disposition ; 2 Hobbes rather let it be seen that his natural istic opinion, like the Epicurean, saw in ideas as to the supernatural a superstition resting upon a defective knowledge of Nature, — a superstition which by the regulation of the state becomes the bind ing authority of religion. 8 Much more difficult, however, was the position of those philosophers who held fast to the metaphysical conception of the deity in their very explanation of Nature ; Des cartes' whole literary activity is filled with an anxious caution directed toward avoiding every offence to religion, while Leibniz could attempt to carry through in a much more positive manner the conformity of his metaphysics to religion ; and on the other hand the example of Spinoza showed how dangerous it was if philosophy openly brought to the front the difference between its conception of God and the dogmatic conception.
1. The main difficulty of the case inhered in the circumstance that the new methodical principle of mechanics excluded all tracing of
i Cf. the letter to the Grand Duchess Christine, Op. II. 26 ft*.
s De Augm. Scient. IX. , where the supernatural and incomprehensible is set
forth as the characteristic and serviceable quality of faith. * Leviathan, I. 6 ; cf. the drastic expression, ib, IV. 32.
Chap. 2, § 31. ] Substance and Causality : Bacon. 401
corporeal phenomena back to spiritual forces. Nature was despiritu- alised ; science would see in it nothing but the movements of smallest bodies, of which one is the cause of the other. No room remained for the operation of supernatural powers. So first of all, at one stroke, magic, astronomy, and alchemy, in which the Neo-Platonic ghosts and spirits had held sway, became for science a standpoint of the past Leonardo had already demanded that the phenomena of the external world should be explained by natural causes only ; the great systems of the seventeenth century without exception recognise only such, and a Cartesian, Balthasar Bekker, wrote a book ' to show that in accordance with the principles of modern science, all appear ances of ghosts, conjurations, and magic arts must be reckoned as injurious errors, — a word of admonition which was very much in
place in view of the luxuriant superstition of the Renaissance.
But with the spirits, teleology, also, was obliged to give place.
The explanation of natural phenomena by their purposiveness always came ultimately in some way or other to the thought of a spiritual creation or ordering of things, and so was contradictory to the principle of mechanics. At this point the victory of the system of Democritus over the natural philosophy of Plato and Aristotle was most palpable ; this, too, was emphasised most forcibly by the new philosophy. Bacon counted the teleological mode of regarding Nature as one of the idols, and, indeed, as one of the dangerous idols of the tribe, — the fundamental errors which become a source of illusion to man through his very nature : he taught that
philosophy has to do only with formal or efficient causes, and ex pressed his restriction of philosophy to physics and his rejection of metaphysics precisely by saying that the explanation of Nature is
if it concerns causm efficientes, metaphysics if it concerns causae finale*} In the case of Hobbes, who was the disciple of Bacon and Galileo, the same view is self-explaining. But Descartes, also, desires to see all final causes kept at a distance from the explanation of Nature — he declares it audacious to desire to know the purposes of God. ' Much more open, and keenest by far, is the
polemic of Spinoza* against the anthropomorphism of teleology. In view of his idea of God and God's relation to the world, it is absurd to speak of ends of the deity, and especially of such as have reference to men ; where all follows with eternal necessity from the essential nature of the deity, there is no room for an activity accord ing to ends. The English Neo-Platonists, such as Cudworth Shd
« Balthaur Bekker (1634-1898), De Betoeerte Wereld (1690). * De Angm. III. 4. > Med. IV.
* Cf. principally Kih. I. Append.
physics
402 The. Renaissance : Natural Science Period. [Part IV.
Henry More, combated this fundamental mechanico-antiteleological feature of the new metaphysics with all the eloquence of the old arguments, but without success. The teleological conviction was obliged to renounce definitively the claim of affording scientific explanation of particular phenomena, and only in the metaphysical conception of the whole did Leibniz (cf. below, No. 8), and similarly a part of the English students of Nature, find ultimately a satisfac
tory adjustment between the opposing principles.
With the exclusion of the spiritual from the explanation of
Nature, still a third element of the old view of the world fell away, viz. the thought of the difference in kind and in value of the spheres of Nature, as it had been embodied most distinctly in the Neo-Platonic graded realm of things, following the ancient Pythagorean precedent. In this respect the fantastic natural philosophy of the Renaissance had already done a forcible work of preparation. The Stoic doctrine of the omnipresence of all sub stances at every point of the universe had been revived by Nicolaus Cusanus ; but it was in connection with the victory of the Coperni- can system, as we see in Bruno, that the idea of the homogeneity
of all parts of the universe first completely forced its way to recogni
tion. The sublunary world could no longer be contrasted as the realm of imperfection, with the more spiritual spheres of the stellar heaven; matter and motion are alike in both. It was from this thought that Kepler and Galileo proceeded, and it became complete when Newton recognised th« identity of force in the fall of the apple and the revolution of the stars. For modern science, the old distinction in essence and in value between heaven and earth exists no longer. The universe is one in nature throughout. This same view, moreover, presented itself in opposition to the Aristotelian and Thomistic development system of Matters and Forms. It did away with the whole army of lower and higher forces — the much combated qualitates occulta; ; it recognised the mechanical principle of motion as the only ground of explanation for all phenomena, and therefore, removed also the distinction in principle between the ani mate and the inanimate. Though here Neo-Platonism had co operated toward overcoming this antithesis by its view of the animation of the entire universe, the reverse task now arose for the Galilean mechanics, namely, that of explaining mechanically the phenomena of life also. The discovery of the mechanism of the circulation of the blood by Harvey l (1626) gave to this tendency a
1 In which he had been anticipated by Michael Servetus (burned 1553 in Geneva by Calvin's instrumentality).
•
Chap. 2, §31. ] Substance and Causality: Descartes, Locke. 403
vigorous impulse ; Descartes expressed it in principle in his state ment that the bodies of animals are to be regarded scientifically as most complex automata, and their vital activities as mechanical
Hobbes and Spinoza carried out this thought more exactly ; a zealous study of reflex motions began in the medical schools of France and the Netherlands, and the conception of the soul as vital force became completely disintegrated. Only the Platonists and the adherents of the vitalism of Paracelsus and Boehme, such as Van Hehnont, held fast to this conception in the old manner.
This mechanistic despiritualisation of Nature corresponded completely to that dualistic theory of the world, which from episte- mological motives had been in course of preparation in terministic Nominalism, — the theory of total difference between the inner and the outer icorld. To the knowledge of their qualitative difference was now added that of their real and causal separateness. The world of bodies appeared not only quite different in kind from that of mind, but also as entirely sundered from in its existence and in the course of its motions. The doctrine of the intellectuality of the sense qualities, revived in the philosophy of the Renaissance by the Humanists, had contributed an extraordinary amount toward sharpening the above antithesis. The doctrine tliat colours, tones, smells, tastes, and qualities of pressure, heat, and touch are not real qualities of things, but only signs of such in the mind, had passed over from the Sceptical and Epicurean literature into most of the doctrines of modern philosophy with repetition of the ancient illustrations. Vives, Montaigne, Sanchez, and Campanella were at one in this Galileo, Hobbes, and Descartes revived the teaching of Democritus, that to these qualitative differences of perception noth
ing but quantitative differences correspond in the natura rerum, and this in such way that the former are the inner modes of mentally representing the latter. Descartes regarded sense qualities as ob scure and confused ideas, while the conception of the quantitative determinations of the outer world, on account of its mathematical character, was for him the only clear and distinct idea of them.
According to Descartes, therefore, not only the sensuous feelings, but also the contents of sensation, belong not to the spatial, but to the psychical world only, and represent in this sphere the geomet rical structures of which they are the signs. In our examination of an individual object we can,1 to be sure, gain a knowledge of this
Ct. Med. VI. which allows pcrliapt the plainest view of the very clow relation which I>>-«c»rt< »' [I'lvsicil ■<•arch had t<>experience.
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404 The Renaissance : Natural Science Period. [Part IV.
true mathematical essence of bodies only by the aid of perceptions, and in these perceptions the true mathematical essence is always alloyed with the qualitative elements of the "imagination. " But just in this consists the task of physical research, to dissolve out this real essence of bodies from the subjective modes of our mental representation by means of reflection upon the clear and distinct ele ments of perception. John Locke, who later adopted and made popular this view of Descartes, designated ' those qualities which belong to bodies in themselves as primary, and called those sec ondary, on the other hand, which belong to a body only by virtue of its action upon our senses. 2 Descartes allowed as primary qualities only shape, size, position, and motion, so that for him the physical body coincided with the mathematical (cf. below, No. 4). In order to maintain a distinction between the two, Henry More,3 on the con trary, demanded that impenetrability, regarded as the property of filling space, should also be reckoned to the essential nature of bodies, and Locke,4 in accordance with this view, took up " solidity " into the class of primary qualities.
With Hobbes 5 these thoughts become modified more in accordance with the terministic conception. He regards space (as phantasma rei existentis) and time (as phantasma motus) as also modes of men tal representation, and it is just because we can therefore construct these ourselves that mathematical theory has the advantage of being the sole rational science. But instead of drawing phenomenalistic conclusions from this premise, he argues that philosophy can treat only of bodies, and must leave everything spiritual to revelation. Scientific thought consequently consists, for him, only in the imma nent combination of signs. These are partly involuntary in percep tions, partly arbitrary in words (similarly Occam, cf. § 27, 4). It is only by means of the latter that general conceptions and proposi tions become possible. Our thinking is hence a reckoning with verbal signs. It has its truth in itself and stands as something completely heterogeneous by the side of the outer world to which it relates.
3. All these suggestions become compressed in the system of Descartes to form the doctrine of the dualism of substances. The analytic method was intended to discover the simple elements of reality which were self-explanatory and not susceptible of farther
1 Essay, Human Understanding, II. 8, § 23 f.
a As tertiary qualities, Locke added further the " powers " for the operation of one body upon others.
•Desc. (Euv. (C), X. pp. 181 ff.
« Essay, II. 4.
6 Human Nature, chs. 2-6 ; Leviathan, cha. 4 ff.
Chap. 2, § 31. ] Substance and Causality : Hobbes, Descartes. 405
deduction. Descartes discovered that all that can be experienced is a species either of spatial or of conscious Being or existence. Spa- tiality, or the quality of filling space, and consciousness (" extension " and "thought" according to the usual translation of extensio and cogi- tatio) are the ultimate, simple, original attributes of reality. All that is is either spatial or conscious. For these two prime predi cates are related disjunctively. What is spatial is not conscious ; what is conscious is not spatial. The self-certainty of mind is only that of the personality as a conscious being. Bodies are real in so far as they have in themselves the quantitative determinations of spatial existence and change, of extension and motion, All things are either bodies or minds ; substances are either spatial or con scious : res extensat and res cogitantes.
The world falls thus into two completely different and completely separated realms : that of bodies and that of minds. But in the background of this dualism there stands in the thought of Descartes the conception of the deity as the ens perfectissimum or perfect sub stance. Bodies and minds are finite things; God is infinite Being.
1 The Meditations leave no doubt as to the fact that Descartes ac cepted the conception of God quite in accordance with the inter
pretation of scholastic Realism. The mind in its own Being, which it recognises as a limited and imperfect one, apprehends with the same intuitive certainty the Reality of the perfect, infinite Being also (cf. above, $ 30, 5). To the ontological argument is added the relation of God and the world in the form brought forward by Nicolaus Cusanus, namely, that of the antithesis of the infinite and the finite. But the above-mentioned relationship with the Realism of the Middle Ages appears most distinctly in the development of metaphysics that succeeded Descartes : for the pantheistic conse quences of this presupposition, which had been carefully held back in the scholastic period, were now spoken out with complete clear ness and sureness. And if we find in the doctrines of Descartes' successors a strong similarity with those which in the Middle Ages could lead but a more or less repressed existence, this is intelligible »-ven without the assumption of a direct historical dependence, merely by the pragmatic connection and the logical necessity of the conclusions.
4- The common metaphysical name of "substance," applied to God in the infinite sense, and to minds and bodies in a finite sense, could not permanently cover the problems which were hidden be-
• So likewise Malebrancbe said (Rrrh. III. 2. 0 a. K. ) that Ood could properly ba called only Celui qui est, be is ritre sans restriction, tout ttre injlni tit vairertei.
406 The Renaissance : Natural Science Period. [Part IV.
neath it. The conception of substance had come into a state of flux, and needed " further re-shaping. It had almost lost touch with the idea of thing," the category of inherence ; for just the combi nation of a multiplicity of determinations into the idea of a unitary concrete entity, which is essential to this category, was completely lacking in Descartes' conception of finite substances, since these were held to be characterised by one fundamental quality, spatiality or consciousness. All else that was found in substances must there fore be regarded as a modification of its fundamental quality, of its attribute. All qualities and states of bodies are modes of their spa tiality or extension: all qualities and states of mind are modes of consciousness (modi cogitandi).
It is involved in this that all particular substances belonging to either class, all bodies on the one hand and all minds on the other, are alike in their essence, their constitutive attribute. But from this it is only a step farther to the idea in which this likeness is thought as metaphysical identity. All bodies are spatial, all minds are conscious ; individual bodies are distinguished from one another only by different modes of spatiality (form, size, situation, motion) ; individual minds are distinguished from one another only by differ ent modes of consciousness (ideas, judgments, activities of will). Individual bodies are modes of spatiality, individual minds are modes of consciousness. In this way the attribute obtains meta physical preponderance over individual substances, which now appear as its modifications ; the res extensas become modi extension's; the res cogitantes, modi cogitationis.
Descartes himself drew this conclusion only in the domain of natr ural philosophy, to which in general he restricted the carrying out of his metaphysical doctrine in its principles. Here, however, the general conception of modification took on, of itself, a definite sig nificance, and one capable of apprehension by perception or imagina tion, viz. that of limitation (determinatio) . Bodies are parts of space, limitations of the universal space-filling quality or extension. 1 Hence for Descartes the conception of body coincides with that of a limited spatial magnitude. A body as regards its true essence, a portion of space. The elements of the corporeal world are the " corpuscles,"
Cf. Print. Phil. II. f. , where, at the same time, appears quite clearly that this relation of the individual body to universal space made equivalent to that of individual and species.
For the corpuscular theory, Descartes found many suggestions in Bacon, Hobbes, Basso, Sennert, and others. The variety in the development of this theory, which rests upon the dialectic between the mathematical and the physi cal momenta, has more interest for natural science than for philosophy. An excellent exposition found in Lasswitz, GescMchte der Atomistik.
is
21
it is
9
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is,
Chap. 2, § 31. ] Substance and Causality : Malebrancfie. 407
i. e. the firm spatial particles which realiter are no longer divisible : as mathematical structures, however, they are infinitely divisible; that is, there are no atoms. From these presuppositions follow, likewise, for Descartes, the impossibility of empty space, and the infinitude of the corporeal world.
For the mental world the analogous claim was pronounced by Malebranche. In connection with the epistemological motives (cf. below, No. 8) which made it seem to him that no knowledge of things is possible except in God, he came ' to the conception of the raisou universelle, which, as being alike in all individual minds, can not belong to the modes of the finite mind, but is rather that of which finite minds are themselves modifications, and can, just on this account, be none other than an attribute of God. God is in so far the " place of minds " or spirits, just as space is the place of bodies. Here, also, as the expression proves, the relation which obtains in conceptions between the universal and the particular underlies the thought, and following the analogy of the Cartesian conception of space and body this relation is thought in percep tional or picturate terms as participation. * All human insight is a participation in the infinite Reason, all ideas of finite things are but determinations of the idea of God, all desires directed toward the particular object are but participations in that love toward God as the ground of its essence and life, which necessarily dwells in the finite mind. To be sure, Malebranche came into a very critical situation by thus making the finite mind disappear completely in the universal divine mind, as its modification. For how, in accord ance with this, should he explain the self-subsistence and self- activity which it seemed were quite notoriously present in those inclinations and volitions of man which opposed God ? In this difficulty nothing availed but the word " freedom," in using which Malebranche was indeed obliged to confess that freedom was an impenetrable mystery. 3
5. In this course of thought pursued by Malebranche appears clearly the inevitable logical consistency with which the attributes, which were regarded by Descartes as the common essence belonging to either of the two classes of finite substances, could ultimately be thought only as the attributes of the infinite substance or deity. Hut precisely in this point consists the fundamental motive of Spi- nozism, which developed along this line out of Cartesianism directly
and at the outset, and at the same time developed to the farthest
1 Rtck. de la Vtr. III. 2, 8 ; Sntret. I. 10.
> Recall tin- Platonic Wfefts I > Cf. above, p. 394, note 3.
408 The Renaissance : Natural Science Period. [Part IV.
consequence. Spinozism likewise holds as firmly to the qualitative as to the causal dualism of spatiality and consciousness. The spa tial and the spiritual worlds are entirely heterogeneous and abso lutely independent of each other. But the whole endless series of bodies, with their divisions, forms, and motions, are only the modes of extension, just as the endless series of minds with their ideas and volitions are only the modes of consciousness. Hence these finite " things " are no longer entitled to the name of " substance. " That only can be called substance, whose attributes are extension and consciousness themselves, viz. the infinite existence or Being, the deity. But its essence, in turn, cannot be exhausted in these two attributes which are accessible to human experience ; the ens realissimum involves within itself the actuality of the infinite num ber of all possible attributes.
The ultimate ground of this position also lies in the scholastic- realistic conception of the most real being. Spinoza's definition of substance or the deity, as the essence {essentia) which involves its own existence, is only the condensed expression of the ontological proof for the existence of God : the " asettas " is preserved in the term " causa sui " ; substance as that " quod in se est et per se con- cipitur" is again but another transcription of the same thought. Proceeding from these definitions, the proof for the oneness and infinitude of substance x followed as a matter of course.
That, however, we have here to do with an entirely realistic course of thought becomes clearly manifest from Spinoza's doctrine of the nature of substance itself and of its relation to the attributes. For the Spinozistic system says absolutely nothing of substance or of the deity farther than the formal determinations contained in the conception of the ens realissimum, of absolute Being. Every predi cate expressing any content on the contrary, expressly denied and in particular Spinoza especially careful to refuse to the divine essence the modifications of consciousness, such as intellectual cog nition [intellectus, Erkenntniss~\ and will. Just as little of course does he recognise the modifications of extension as being predicates of the divine essence, though he had no polemical inducement to express this especially. God himself therefore neither mind nor body of him can only be said, that he is. It evident that the old principle of negative theology here present with a changed form of expression. Knowledge of all finite things and states leads to two highest universal conceptions space-filling quality or exten sion, and consciousness. To both of these
higher metaphysical Eth. Props. 1-14. lb. 31.
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Chap. 2, § 31. ] Substance and Causality : Spinoza. 409
dignity is ascribed than to finite things ; they are the attributes, and the things are their modes. But if the process of abstraction now rises from these two determinations, the last which contain any content, to the most general, to the ens generalissimum, then all definite content falls away from the conception of this being, and only the empty Form of substance is left. For Spinoza, also, the deity is all and thus — nothing. His doctrine of God lies quite along the path of Mysticism. 1
But if God is thus the general essence of finite things, he does not exist otherwise than in them and with them. This applies first of all to the attributes. God is not distinct from them, and they are not distinct from him, just as the dimensions of space are not dis tinct from space itself. Hence Spinoza can say also that God con sists of countless attributes, or Deus si ve omnia ejus attributa* And the same relation is afterwards repeated between the attributes and the modes. Every attribute, because it expresses the infinite essence of God in a definite manner, is again infinite in its own way ; but it does not exist otherwise than with and in its countless modifica tions. God then exists only in things as their universal essence, and they only in him as the modes of his reality. In this sense Spinoza adopts from Nicolaus Cusanus and Giordano Bruno the expressions natura naturans and natura naturata. God is Nature : as the universal world-essence, he is the natura naturans; as sum- total of the individual things in which this essence exists modified, he is the natura naturata. If in this connection the natura naturans is called occasionally also the efficient cause of things, this creative force must not be thought as something distinct from its workings ; this cause exists nowhere but in its workings. This is Spinoza's complete and unreserved pantheism.
Finally this relation is repeated yet again in the distinction which Spinoza establishes between the infinite and the finite modes. ' If each of the countless finite things is a mode of God, the infinite connection or coherence which exists between them must also be regarded as a mode, and, indeed, as an infinite mode. Spinoza affirms three of these. 4 The deity as the universal world-thing appears in individual things, which are finite modes ; to them corresponds as
1 To this"corresponds also hla theory of cognition with its three stages, which sets intuition," u the immediate apprehension of the eternal logical remitting of all thing* from God, an knowledge sub specie aeternitatis, above perception and the activity of the intellect.
* which, however, is in nowise to be interpreted aa if the attributes were •df-aabflistent prime realities and "God" only the collective name for them (a* K. Thomas supposed, Sp- ats itetaphy Biker, Konigxberg, 1840). Such a rraaaly nominalistic cap-stone would press the whole system out of joint.
» Ktk. I. 23 and 30 ff. « Sp. 64 (Op. II. HV).
410 The Renaissance : Natural Science Period. [Part IV.
infinite mode the universe. In the attribute of extension the finite modes are the particular space-forms ; the infinite mode is infinite space, or matter ' itself in its motion and rest. For the attribute of consciousness, the intellectus infinitus1 stands beside the particular functions of ideation and will. Here Spinoza reminds us imme diately of the realistic pantheism of David of Din ant (cf. § 27, 1). His metaphysics is the last word of mediaeval Realism. '
6. With these motives relating to the problem of the qualitative difference of substances modern philosophy struggled out of its dualistic presuppositions to a monistic adjustment ; but at the same time, still more powerful motives became mingled in the process, — motives which grew out of the real and causal separation of the spatial and the conscious worlds. At first, indeed, it was the principles of mechanics themselves which demanded the attempt to isolate completely the course of events in each of the two spheres of finite substances.
This succeeded in the corporeal world in a relatively simple manner. In this domain, the idea of cause had acquired a completely neiv significance through Galileo. According to the scholastic con ception (which even in Descartes' Meditations, in a decisive passage, was still presented with axiomatic validity) causes were substance* or things, while effects, on the other hand, were either their activities or were other substances and things which were held to come about only by such activities : this was the Platonic-Aristotelian concep tion of the oitux. Galileo, on the contrary, went back to the idea of the older Greek thinkers (cf. § 5), who applied the causal relation only to the states — that meant now to the motions of substances — not to the Being of the substances themselves. Causes are motions, and effects are motions. The relation of impact and counter-impact, of the passing over of motion from one corpuscle to another,* is the original fundamental form of the causal relation, the form which is clear to perception or imagination (anschaulich), is intelligible in
1 Tins equivalence holds good with Spinoza as well as with Descartes.
2 This intellectus infinitus appears again in the ethical part of the Spinozistic system as amor intellectuals quo deus se. ipsum amat. In both cases Male- branche's " raison universelle " amounts to the same thing.
8 Geulincx also, in a mauner similar to that of Spinoza and Malebranche, regards finite bodies and minds as only "limitations," " prcecisiones " of the universal infinite body and the divine mind. Cf. Met. p. 56. If we think away limitation from ourselves, he says, ib. 237 ff. , there is left — God.
4 Hence for Descartes the mechanical principle excluded possibility of action at a distance, just as it excluded empty space. This forced him to the artificial hypotheses of the vortex theory, by which he aimed to give a physical ground for the Copernican view of the world (popular exposition by Fontenelle, Entretiens sur la Pluralite des Mondesi 1686). The grounds on which this doctrine was displaced by the Newtonian theory of gravitation are no longer philosophical, but purely physical in their nature.
Chap. 2, $ 31. ] Substance and Causality : Galileo, Descartes. 411
itself, and explains all others. And the question as to the nature of this fundamental relation was answered by the principle of math ematical equality, which, in turn, passed over into that of metaphysi cal identity. So much motion in the cause, so much in the effect also. Descartes formulated this as the law of the conservation of motion in Nature. The sum of motion in Nature remains always the same : what a body loses in motion it gives to another. As regards the amount of motion, there is in Nature nothing new, especially no impulse from the spiritual world. ' Even for the king dom of organisms this principle was carried through, at least as a postulate, though as yet with very weak grounds. Animals, also, are machines whose motions are evoked and determined by the mechanism of the nervous system. Descartes thought of this mechanism more precisely (and with him Hobbes and Spinoza) as a motion of finest (gaseous) substances, the so-called spirit us ani- males,* and sought the point of transition from the sensory to the motor nervous system in man, in a part of the brain which has no correlative, i. e. is a single and not a j>aired organ, the pineal gland or eonarium.
The other part of the task proved much more difficult : namely, that of understanding the mental life without any relation to the corporeal world. Easy and clear to perception as was the action of one body upon another, it did not yield a mode of representing an incorporeal connection between different minds, that could be used scientifically. Spinoza, for example, expressed the general meta physical postulate very energetically, when he promised in entering upon the third book of the Ethics, that he would treat the actions and desires of man as if lines, surfaces, and bodies were the subject of discussion ; for the important thing is neither to asperse them nor to deride them, but to understand them. But the solution of this problem was limited in advance to investigating the causal connec tion between the activities of consciousness in the individual mind : dualism demanded a psychology free from all physiological constitu ents. It is all the more characteristic of the predominance of the spirit of natural science in the seventeenth century, that it attained this psychology demanded by the theory, only in the most limited degree. And even the beginnings toward this are ruled by the endeavour to apply the methodical principle of mechanics, which
1 Henoe Hobbes excluded from physics the Aristotelian and ThomUtic concep tion of the unmoved mover, while Descartes, who in this point also proceeded mure metaphysically, made motion to have been communicated to matter at the beginning by God.
* An inheritance from the physiological psychology of the (ireeks, in particu lar from that of the l'eripatetics.
412 Tlie Renaissance: Natural Science Period. [Part IV.
was celebrating its triumphs in the theory of outer experience, to the comprehension of the inner world also.
For just as the investigation of Nature from Galileo to Newton directed its energies toward finding out the simple fundamental form of corporeal motion, to which all complex structures of outer experience could be reduced, so Descartes desired to establish the fundamental forms of psychical motion, out of which the multiplic ity of inner experiences would become explicable. In the theoreti cal domain this seemed attained by establishing the immediately evident truths (the innate ideas) ; in the practical field there grew out of this demand the new problem of a statics and a mechanics of the movements of feeling (Gemuthsbewegungen) . In this spirit Des cartes and Spinoza produced their natural history of the emotions (Affecte) and passions,1 the latter author by combining the thoughts of the former with those of Hobbes. Thus Descartes derives the whole host of particular passions, as species and sub-species, from the six fundamental forms of wonder (admiratio), love, and hate, desire {disir), pleasure and pain [or joy and sadness, Lust und
Unlust~\ (lostitia — tristitia) ; thus Spinoza develops his system of the emotions out of desire, pleasure, and pain (appetitus, Icetitia,
by pointing out the ideational processes in connection with which these emotions have become transferred from their original object, the self-preservation of the individual, to other " ideas. "
A peculiar side-attitude is taken in this regard by the two English thinkers. For Bacon and Hobbes, a mechanical conception of the mental is the more natural in proportion as they endeavour to draw the mental more closely into the circle of the physical. Both, that regard the empirical psychical life, and therefore, also, the sphere of consciousness which in Descartes' system was to have nothing to do with the corporeal world, as something which essen tially belongs thereto on the other hand, there set over against the whole world of perception rather something spiritual [spirit ual in the religious sense, Geistliches'] than something mental or intellectual [Geistiges]. Ideas and volitions as they are known by experience are held to be at bottom activities of the body also, and
besides these we speak yet of an immortal soul (spiraculum), of spiritual world and of the divine mind or spirit, this should fall to the province of theology. But according to this view the natural science theory cannot be characterised much otherwise than as an
Descartes, Lts Passions de VAme Spinoza, Eth. III. , and Tract. Brev. II. fl. Cl. below, No.
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Chap. 2, $ 30. ] Problem of Method : Spinoza, Leibniz. 397
inferences. Especially did the mathematically schooled Cartesians in Germany take up the geometrical method along this line : this was done by Jung and Weigel, and the academic impulse to the preparation of text-books found in this method a form with which it could have the utmost sympathy. In the eighteenth cen tury Christian Wolff (cf. Part V. ) pursued this line in the most comprehensive manner with his Latin text-books, and for the sys- tematisation of a firmly established and clearly thought out material there could be in fact no better form. This was shown when Puffen-
dorf undertook to deduce the entire system of Natural Right by the geometrical method, as a logical necessity from the single principle of the need of society.
When this view was in process of coming into existence Leibniz came into sympathy with it under the especial influence of Erhard Weigel, and was at the beginning one of its most consistent sup
He not only made the jest of giving this unwonted garb to a political brochure,1 but was seriously of the opinion that philo sophical controversies would find their end for the first time when a philosophy could once make its appearance in as clear and certain a form as that of a mathematical calculation. *
Leibniz pursued this thought very energetically. The stimulus of Hobbes, who also — though with quite another purpose, cf. § 31, 2 — declared thinking to be a reckoning with the conceptional signs of things, may have been added ; the Art of Lull and the pains which Giordano Bruno had taken with its improvement were well known to him. In Cartesian circles, also, the thought of transform ing the mathematical method to a regular art of invention had been
much discussed : besides Joachim Jung, the Altorf Professor Joh. Christopher Sturm,3 had also exercised an influence upon Leibniz in this respect. Finally, the thought of expressing the fundamental metaphysical conceptions, and likewise the logical operations of their combination after the manner of the mathematical sign-lan guage by definite characters, seemed to offer the possibility of writ ing a philosophical investigation in general formula1, and by this means raising it beyond the capability of being expressed in a
definite language — an effort toward a universally scientific lan guage, a " Lingua Adamica," which likewise appeared at the time
* In the pseudonymous Specimen drmonMratinnum politieanim pro rr<>r Polo- norum tligendo (MW9), he proved by "geometrical mt-tliod" in sixty proposi tions and demonstration* that the Count Palatine of Neuhiiix imutt be chosen king of the Pole*. -^
* De Srlrntin Vmvertali ten Calrulo Phllotophico (U>«4). ' * The author of a Compendium Univrrtalium sen Metaphyiicu KurlUIn*
regular
porters.
The Renaissance : Natural Science Period. [Part IV.
of Leibniz in numerous supporters. 1 So, too, Leibniz busied himself to an extraordinary degree with the thought of a characteristica uni versalis, and a method of philosophical calculus. 2
The essential outcome of these strange endeavours was, that an attempt was necessarily made to establish those highest truths, from the logical combination of which all knowledge was to be deduced. So Leibniz, like Galileo and Descartes, must proceed to search out that which, as immediately and intuitively certain, forces itself upon the mind as self-evident, and by its combinations grounds all derived knowledge. In the course of these reflections Leibniz stumbled upon the discovery3 (which Aristotle had made before him), that there are two completely different kinds of this intuitive knowledge : universal truths self-evident to reason, and facts of experience. The one class has timeless validity ; the other, validity for a single instance : viritis iternelles and vtrite's de fait. Both have in common that they are intuitively certain, i. e. are certain in them selves and not by deduction from anything else ; they are called, therefore, prima veritates, or, also, primes possibiiitates, because in them the possibility of all that is derivative has its ground. For the " possibility " of a conception is known either by a " causal definition " which derives the same from the first possibilities, that is, a priori; or by the immediate experience of its actual existence, that is, a, posteriori.
These two kinds of "primitive truths" — the rational and the empirical, as we see — Leibniz attached in a very interesting manner to the two Cartesian marks of intuitive self-evidence, clearness and distinctness. To this end he shifts to a slight extent the meaning of both expressions. 4 That idea is clear which is surely distin guished from all others and so is adequate for the recognition of its object; that idea is distinct which is clear even to its particular constituent parts and to the knowledge of their combination. According to this, the a priori, "geometrical" or "metaphysical" eternal truths are clear and distinct ; while on the other hand the a posteriori, or the truths relating to facts, are clear, indeed, but not distinct. Hence the former are perfectly transparent, conjoined with the conviction of the impossriblity of the opposite, while in the case of the latter the opposite is thinkable. In the case of the former the intuitive certainty rests upon the Principle of Contradic
1 Such attempts had been projected by J. J. Becker (1661 ), G. Dalgarn (1661), Athanasius Kircher (1663), and J. Wilkins ( 1668).
* Cf. A. Trendelenburg, Historische Beitrage zu Philosophic, Vols. II. , III. 8 Meditationes de Cognitions Veritute et Idris (1684).
* lb. at the beginning, Erd's. ed. , p. 79.
Chap. 2, § 31. ] Substance and Causality. 399
twn; in the case of the latter the possibility guaranteed by the actual fact needs still an explanation in accordance with the Prin
ciple of Sufficient Reason.
At the beginning, Leibniz intended this distinction only with
reference to the imperfection of the human understanding. In the case of rational truths we see into the impossibility of the opposite ; with empirical truths this is not the case, and we must content our selves with establishing their actuality : ' but the latter also, in the natura rerum and for the divine understanding, are so grounded that the opposite is impossible, although it remains thinkable for us. If Leibniz compared this distinction with that of commensur able and incommensurable magnitudes, he meant at the beginning that incommensurability lies only in man's limited knowing capacity. But in the course of his development this antithesis became for him an absolute one ; it gained metaphysical significance. Leibniz now distinguished realiter between an unconditional necessity, which involves the logical impossibility of the opposite, and a conditional necessity, which has " only " the character of a matter of fact. He divided the principles of things into those of which the opposite is unthinkable, and those of which the opposite is thinkable : he dis tinguished metaphysically, also, between necessary and contingent truths. This, however, cohered with metaphysical motives, which arose from an after-working of the Scotist theory of the contin gency of the finite, and overthrew the geometrical method.
§ 31. Substance and Causality.
The real [as contrasted with formal] result of the new methods was in metaphysics, as in natural science, a transformation of the fundamental ideas of the nature of things, and of the mode of their connection in the processes of Nature : the conceptions of sub stance and causality acquired a new content. Hut this change could not proceed so radically in metaphysics as in natural science. In this latter more limited realm, after the Galilean principle had once been found, it was possible in a certain measure to begin ab ovo and produce a completely new theory : in the more general philo sophical doctrines the power and authority of tradition were much too great to make it possible or permissible that it should be completely set aside.
This distinction asserted itself already in connection with the delicate relation sustained to religious conceptions. Natural science
1 The Aristotelian distinction of Mti and An,
400 The Renaissance : Natural Science Period. (Taet IV.
could isolate itself absolutely from theology, and maintain toward it an attitude of complete indifference : metaphysics, by its concep tion of the deity and by its theory of the mental or spiritual world, was brought again and again into hostile or friendly contact with the religious sphere of ideas. A Galileo declared that the investigations of physics, whatever their result might be, had not the least thing to do with the teaching of the Bible,1 and a Newton was not prevented by his mathematical natural philosophy from burying himself with the most ardent piety in the mysteries of the Apocalypse. But the metaphysicians, however indifferent their thought as regards religion, and however strictly they might prose cute their science in the purely theoretical spirit, were still always obliged to consider that they had to do with objects concerning which the Church doctrine was fixed. This gave modern philosophy a somewhat delicate position : mediaeval philosophy had brought to the objects of Church dogma an essentially religious interest of its own as well ; modern philosophy regarded them, if at all, from the theoretical standpoint only. Hence those felt themselves most secure who, like Bacon and Hobbes, restricted philosophy also entirely to natural research, declined to enter upon a metaphysics proper, and were willing to let dogma speak the only words with regard to the deity and the super-sensible destiny of man. Bacon did this with large words behind which it is difficult to recognise his true disposition ; 2 Hobbes rather let it be seen that his natural istic opinion, like the Epicurean, saw in ideas as to the supernatural a superstition resting upon a defective knowledge of Nature, — a superstition which by the regulation of the state becomes the bind ing authority of religion. 8 Much more difficult, however, was the position of those philosophers who held fast to the metaphysical conception of the deity in their very explanation of Nature ; Des cartes' whole literary activity is filled with an anxious caution directed toward avoiding every offence to religion, while Leibniz could attempt to carry through in a much more positive manner the conformity of his metaphysics to religion ; and on the other hand the example of Spinoza showed how dangerous it was if philosophy openly brought to the front the difference between its conception of God and the dogmatic conception.
1. The main difficulty of the case inhered in the circumstance that the new methodical principle of mechanics excluded all tracing of
i Cf. the letter to the Grand Duchess Christine, Op. II. 26 ft*.
s De Augm. Scient. IX. , where the supernatural and incomprehensible is set
forth as the characteristic and serviceable quality of faith. * Leviathan, I. 6 ; cf. the drastic expression, ib, IV. 32.
Chap. 2, § 31. ] Substance and Causality : Bacon. 401
corporeal phenomena back to spiritual forces. Nature was despiritu- alised ; science would see in it nothing but the movements of smallest bodies, of which one is the cause of the other. No room remained for the operation of supernatural powers. So first of all, at one stroke, magic, astronomy, and alchemy, in which the Neo-Platonic ghosts and spirits had held sway, became for science a standpoint of the past Leonardo had already demanded that the phenomena of the external world should be explained by natural causes only ; the great systems of the seventeenth century without exception recognise only such, and a Cartesian, Balthasar Bekker, wrote a book ' to show that in accordance with the principles of modern science, all appear ances of ghosts, conjurations, and magic arts must be reckoned as injurious errors, — a word of admonition which was very much in
place in view of the luxuriant superstition of the Renaissance.
But with the spirits, teleology, also, was obliged to give place.
The explanation of natural phenomena by their purposiveness always came ultimately in some way or other to the thought of a spiritual creation or ordering of things, and so was contradictory to the principle of mechanics. At this point the victory of the system of Democritus over the natural philosophy of Plato and Aristotle was most palpable ; this, too, was emphasised most forcibly by the new philosophy. Bacon counted the teleological mode of regarding Nature as one of the idols, and, indeed, as one of the dangerous idols of the tribe, — the fundamental errors which become a source of illusion to man through his very nature : he taught that
philosophy has to do only with formal or efficient causes, and ex pressed his restriction of philosophy to physics and his rejection of metaphysics precisely by saying that the explanation of Nature is
if it concerns causm efficientes, metaphysics if it concerns causae finale*} In the case of Hobbes, who was the disciple of Bacon and Galileo, the same view is self-explaining. But Descartes, also, desires to see all final causes kept at a distance from the explanation of Nature — he declares it audacious to desire to know the purposes of God. ' Much more open, and keenest by far, is the
polemic of Spinoza* against the anthropomorphism of teleology. In view of his idea of God and God's relation to the world, it is absurd to speak of ends of the deity, and especially of such as have reference to men ; where all follows with eternal necessity from the essential nature of the deity, there is no room for an activity accord ing to ends. The English Neo-Platonists, such as Cudworth Shd
« Balthaur Bekker (1634-1898), De Betoeerte Wereld (1690). * De Angm. III. 4. > Med. IV.
* Cf. principally Kih. I. Append.
physics
402 The. Renaissance : Natural Science Period. [Part IV.
Henry More, combated this fundamental mechanico-antiteleological feature of the new metaphysics with all the eloquence of the old arguments, but without success. The teleological conviction was obliged to renounce definitively the claim of affording scientific explanation of particular phenomena, and only in the metaphysical conception of the whole did Leibniz (cf. below, No. 8), and similarly a part of the English students of Nature, find ultimately a satisfac
tory adjustment between the opposing principles.
With the exclusion of the spiritual from the explanation of
Nature, still a third element of the old view of the world fell away, viz. the thought of the difference in kind and in value of the spheres of Nature, as it had been embodied most distinctly in the Neo-Platonic graded realm of things, following the ancient Pythagorean precedent. In this respect the fantastic natural philosophy of the Renaissance had already done a forcible work of preparation. The Stoic doctrine of the omnipresence of all sub stances at every point of the universe had been revived by Nicolaus Cusanus ; but it was in connection with the victory of the Coperni- can system, as we see in Bruno, that the idea of the homogeneity
of all parts of the universe first completely forced its way to recogni
tion. The sublunary world could no longer be contrasted as the realm of imperfection, with the more spiritual spheres of the stellar heaven; matter and motion are alike in both. It was from this thought that Kepler and Galileo proceeded, and it became complete when Newton recognised th« identity of force in the fall of the apple and the revolution of the stars. For modern science, the old distinction in essence and in value between heaven and earth exists no longer. The universe is one in nature throughout. This same view, moreover, presented itself in opposition to the Aristotelian and Thomistic development system of Matters and Forms. It did away with the whole army of lower and higher forces — the much combated qualitates occulta; ; it recognised the mechanical principle of motion as the only ground of explanation for all phenomena, and therefore, removed also the distinction in principle between the ani mate and the inanimate. Though here Neo-Platonism had co operated toward overcoming this antithesis by its view of the animation of the entire universe, the reverse task now arose for the Galilean mechanics, namely, that of explaining mechanically the phenomena of life also. The discovery of the mechanism of the circulation of the blood by Harvey l (1626) gave to this tendency a
1 In which he had been anticipated by Michael Servetus (burned 1553 in Geneva by Calvin's instrumentality).
•
Chap. 2, §31. ] Substance and Causality: Descartes, Locke. 403
vigorous impulse ; Descartes expressed it in principle in his state ment that the bodies of animals are to be regarded scientifically as most complex automata, and their vital activities as mechanical
Hobbes and Spinoza carried out this thought more exactly ; a zealous study of reflex motions began in the medical schools of France and the Netherlands, and the conception of the soul as vital force became completely disintegrated. Only the Platonists and the adherents of the vitalism of Paracelsus and Boehme, such as Van Hehnont, held fast to this conception in the old manner.
This mechanistic despiritualisation of Nature corresponded completely to that dualistic theory of the world, which from episte- mological motives had been in course of preparation in terministic Nominalism, — the theory of total difference between the inner and the outer icorld. To the knowledge of their qualitative difference was now added that of their real and causal separateness. The world of bodies appeared not only quite different in kind from that of mind, but also as entirely sundered from in its existence and in the course of its motions. The doctrine of the intellectuality of the sense qualities, revived in the philosophy of the Renaissance by the Humanists, had contributed an extraordinary amount toward sharpening the above antithesis. The doctrine tliat colours, tones, smells, tastes, and qualities of pressure, heat, and touch are not real qualities of things, but only signs of such in the mind, had passed over from the Sceptical and Epicurean literature into most of the doctrines of modern philosophy with repetition of the ancient illustrations. Vives, Montaigne, Sanchez, and Campanella were at one in this Galileo, Hobbes, and Descartes revived the teaching of Democritus, that to these qualitative differences of perception noth
ing but quantitative differences correspond in the natura rerum, and this in such way that the former are the inner modes of mentally representing the latter. Descartes regarded sense qualities as ob scure and confused ideas, while the conception of the quantitative determinations of the outer world, on account of its mathematical character, was for him the only clear and distinct idea of them.
According to Descartes, therefore, not only the sensuous feelings, but also the contents of sensation, belong not to the spatial, but to the psychical world only, and represent in this sphere the geomet rical structures of which they are the signs. In our examination of an individual object we can,1 to be sure, gain a knowledge of this
Ct. Med. VI. which allows pcrliapt the plainest view of the very clow relation which I>>-«c»rt< »' [I'lvsicil ■<•arch had t<>experience.
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404 The Renaissance : Natural Science Period. [Part IV.
true mathematical essence of bodies only by the aid of perceptions, and in these perceptions the true mathematical essence is always alloyed with the qualitative elements of the "imagination. " But just in this consists the task of physical research, to dissolve out this real essence of bodies from the subjective modes of our mental representation by means of reflection upon the clear and distinct ele ments of perception. John Locke, who later adopted and made popular this view of Descartes, designated ' those qualities which belong to bodies in themselves as primary, and called those sec ondary, on the other hand, which belong to a body only by virtue of its action upon our senses. 2 Descartes allowed as primary qualities only shape, size, position, and motion, so that for him the physical body coincided with the mathematical (cf. below, No. 4). In order to maintain a distinction between the two, Henry More,3 on the con trary, demanded that impenetrability, regarded as the property of filling space, should also be reckoned to the essential nature of bodies, and Locke,4 in accordance with this view, took up " solidity " into the class of primary qualities.
With Hobbes 5 these thoughts become modified more in accordance with the terministic conception. He regards space (as phantasma rei existentis) and time (as phantasma motus) as also modes of men tal representation, and it is just because we can therefore construct these ourselves that mathematical theory has the advantage of being the sole rational science. But instead of drawing phenomenalistic conclusions from this premise, he argues that philosophy can treat only of bodies, and must leave everything spiritual to revelation. Scientific thought consequently consists, for him, only in the imma nent combination of signs. These are partly involuntary in percep tions, partly arbitrary in words (similarly Occam, cf. § 27, 4). It is only by means of the latter that general conceptions and proposi tions become possible. Our thinking is hence a reckoning with verbal signs. It has its truth in itself and stands as something completely heterogeneous by the side of the outer world to which it relates.
3. All these suggestions become compressed in the system of Descartes to form the doctrine of the dualism of substances. The analytic method was intended to discover the simple elements of reality which were self-explanatory and not susceptible of farther
1 Essay, Human Understanding, II. 8, § 23 f.
a As tertiary qualities, Locke added further the " powers " for the operation of one body upon others.
•Desc. (Euv. (C), X. pp. 181 ff.
« Essay, II. 4.
6 Human Nature, chs. 2-6 ; Leviathan, cha. 4 ff.
Chap. 2, § 31. ] Substance and Causality : Hobbes, Descartes. 405
deduction. Descartes discovered that all that can be experienced is a species either of spatial or of conscious Being or existence. Spa- tiality, or the quality of filling space, and consciousness (" extension " and "thought" according to the usual translation of extensio and cogi- tatio) are the ultimate, simple, original attributes of reality. All that is is either spatial or conscious. For these two prime predi cates are related disjunctively. What is spatial is not conscious ; what is conscious is not spatial. The self-certainty of mind is only that of the personality as a conscious being. Bodies are real in so far as they have in themselves the quantitative determinations of spatial existence and change, of extension and motion, All things are either bodies or minds ; substances are either spatial or con scious : res extensat and res cogitantes.
The world falls thus into two completely different and completely separated realms : that of bodies and that of minds. But in the background of this dualism there stands in the thought of Descartes the conception of the deity as the ens perfectissimum or perfect sub stance. Bodies and minds are finite things; God is infinite Being.
1 The Meditations leave no doubt as to the fact that Descartes ac cepted the conception of God quite in accordance with the inter
pretation of scholastic Realism. The mind in its own Being, which it recognises as a limited and imperfect one, apprehends with the same intuitive certainty the Reality of the perfect, infinite Being also (cf. above, $ 30, 5). To the ontological argument is added the relation of God and the world in the form brought forward by Nicolaus Cusanus, namely, that of the antithesis of the infinite and the finite. But the above-mentioned relationship with the Realism of the Middle Ages appears most distinctly in the development of metaphysics that succeeded Descartes : for the pantheistic conse quences of this presupposition, which had been carefully held back in the scholastic period, were now spoken out with complete clear ness and sureness. And if we find in the doctrines of Descartes' successors a strong similarity with those which in the Middle Ages could lead but a more or less repressed existence, this is intelligible »-ven without the assumption of a direct historical dependence, merely by the pragmatic connection and the logical necessity of the conclusions.
4- The common metaphysical name of "substance," applied to God in the infinite sense, and to minds and bodies in a finite sense, could not permanently cover the problems which were hidden be-
• So likewise Malebrancbe said (Rrrh. III. 2. 0 a. K. ) that Ood could properly ba called only Celui qui est, be is ritre sans restriction, tout ttre injlni tit vairertei.
406 The Renaissance : Natural Science Period. [Part IV.
neath it. The conception of substance had come into a state of flux, and needed " further re-shaping. It had almost lost touch with the idea of thing," the category of inherence ; for just the combi nation of a multiplicity of determinations into the idea of a unitary concrete entity, which is essential to this category, was completely lacking in Descartes' conception of finite substances, since these were held to be characterised by one fundamental quality, spatiality or consciousness. All else that was found in substances must there fore be regarded as a modification of its fundamental quality, of its attribute. All qualities and states of bodies are modes of their spa tiality or extension: all qualities and states of mind are modes of consciousness (modi cogitandi).
It is involved in this that all particular substances belonging to either class, all bodies on the one hand and all minds on the other, are alike in their essence, their constitutive attribute. But from this it is only a step farther to the idea in which this likeness is thought as metaphysical identity. All bodies are spatial, all minds are conscious ; individual bodies are distinguished from one another only by different modes of spatiality (form, size, situation, motion) ; individual minds are distinguished from one another only by differ ent modes of consciousness (ideas, judgments, activities of will). Individual bodies are modes of spatiality, individual minds are modes of consciousness. In this way the attribute obtains meta physical preponderance over individual substances, which now appear as its modifications ; the res extensas become modi extension's; the res cogitantes, modi cogitationis.
Descartes himself drew this conclusion only in the domain of natr ural philosophy, to which in general he restricted the carrying out of his metaphysical doctrine in its principles. Here, however, the general conception of modification took on, of itself, a definite sig nificance, and one capable of apprehension by perception or imagina tion, viz. that of limitation (determinatio) . Bodies are parts of space, limitations of the universal space-filling quality or extension. 1 Hence for Descartes the conception of body coincides with that of a limited spatial magnitude. A body as regards its true essence, a portion of space. The elements of the corporeal world are the " corpuscles,"
Cf. Print. Phil. II. f. , where, at the same time, appears quite clearly that this relation of the individual body to universal space made equivalent to that of individual and species.
For the corpuscular theory, Descartes found many suggestions in Bacon, Hobbes, Basso, Sennert, and others. The variety in the development of this theory, which rests upon the dialectic between the mathematical and the physi cal momenta, has more interest for natural science than for philosophy. An excellent exposition found in Lasswitz, GescMchte der Atomistik.
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Chap. 2, § 31. ] Substance and Causality : Malebrancfie. 407
i. e. the firm spatial particles which realiter are no longer divisible : as mathematical structures, however, they are infinitely divisible; that is, there are no atoms. From these presuppositions follow, likewise, for Descartes, the impossibility of empty space, and the infinitude of the corporeal world.
For the mental world the analogous claim was pronounced by Malebranche. In connection with the epistemological motives (cf. below, No. 8) which made it seem to him that no knowledge of things is possible except in God, he came ' to the conception of the raisou universelle, which, as being alike in all individual minds, can not belong to the modes of the finite mind, but is rather that of which finite minds are themselves modifications, and can, just on this account, be none other than an attribute of God. God is in so far the " place of minds " or spirits, just as space is the place of bodies. Here, also, as the expression proves, the relation which obtains in conceptions between the universal and the particular underlies the thought, and following the analogy of the Cartesian conception of space and body this relation is thought in percep tional or picturate terms as participation. * All human insight is a participation in the infinite Reason, all ideas of finite things are but determinations of the idea of God, all desires directed toward the particular object are but participations in that love toward God as the ground of its essence and life, which necessarily dwells in the finite mind. To be sure, Malebranche came into a very critical situation by thus making the finite mind disappear completely in the universal divine mind, as its modification. For how, in accord ance with this, should he explain the self-subsistence and self- activity which it seemed were quite notoriously present in those inclinations and volitions of man which opposed God ? In this difficulty nothing availed but the word " freedom," in using which Malebranche was indeed obliged to confess that freedom was an impenetrable mystery. 3
5. In this course of thought pursued by Malebranche appears clearly the inevitable logical consistency with which the attributes, which were regarded by Descartes as the common essence belonging to either of the two classes of finite substances, could ultimately be thought only as the attributes of the infinite substance or deity. Hut precisely in this point consists the fundamental motive of Spi- nozism, which developed along this line out of Cartesianism directly
and at the outset, and at the same time developed to the farthest
1 Rtck. de la Vtr. III. 2, 8 ; Sntret. I. 10.
> Recall tin- Platonic Wfefts I > Cf. above, p. 394, note 3.
408 The Renaissance : Natural Science Period. [Part IV.
consequence. Spinozism likewise holds as firmly to the qualitative as to the causal dualism of spatiality and consciousness. The spa tial and the spiritual worlds are entirely heterogeneous and abso lutely independent of each other. But the whole endless series of bodies, with their divisions, forms, and motions, are only the modes of extension, just as the endless series of minds with their ideas and volitions are only the modes of consciousness. Hence these finite " things " are no longer entitled to the name of " substance. " That only can be called substance, whose attributes are extension and consciousness themselves, viz. the infinite existence or Being, the deity. But its essence, in turn, cannot be exhausted in these two attributes which are accessible to human experience ; the ens realissimum involves within itself the actuality of the infinite num ber of all possible attributes.
The ultimate ground of this position also lies in the scholastic- realistic conception of the most real being. Spinoza's definition of substance or the deity, as the essence {essentia) which involves its own existence, is only the condensed expression of the ontological proof for the existence of God : the " asettas " is preserved in the term " causa sui " ; substance as that " quod in se est et per se con- cipitur" is again but another transcription of the same thought. Proceeding from these definitions, the proof for the oneness and infinitude of substance x followed as a matter of course.
That, however, we have here to do with an entirely realistic course of thought becomes clearly manifest from Spinoza's doctrine of the nature of substance itself and of its relation to the attributes. For the Spinozistic system says absolutely nothing of substance or of the deity farther than the formal determinations contained in the conception of the ens realissimum, of absolute Being. Every predi cate expressing any content on the contrary, expressly denied and in particular Spinoza especially careful to refuse to the divine essence the modifications of consciousness, such as intellectual cog nition [intellectus, Erkenntniss~\ and will. Just as little of course does he recognise the modifications of extension as being predicates of the divine essence, though he had no polemical inducement to express this especially. God himself therefore neither mind nor body of him can only be said, that he is. It evident that the old principle of negative theology here present with a changed form of expression. Knowledge of all finite things and states leads to two highest universal conceptions space-filling quality or exten sion, and consciousness. To both of these
higher metaphysical Eth. Props. 1-14. lb. 31.
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Chap. 2, § 31. ] Substance and Causality : Spinoza. 409
dignity is ascribed than to finite things ; they are the attributes, and the things are their modes. But if the process of abstraction now rises from these two determinations, the last which contain any content, to the most general, to the ens generalissimum, then all definite content falls away from the conception of this being, and only the empty Form of substance is left. For Spinoza, also, the deity is all and thus — nothing. His doctrine of God lies quite along the path of Mysticism. 1
But if God is thus the general essence of finite things, he does not exist otherwise than in them and with them. This applies first of all to the attributes. God is not distinct from them, and they are not distinct from him, just as the dimensions of space are not dis tinct from space itself. Hence Spinoza can say also that God con sists of countless attributes, or Deus si ve omnia ejus attributa* And the same relation is afterwards repeated between the attributes and the modes. Every attribute, because it expresses the infinite essence of God in a definite manner, is again infinite in its own way ; but it does not exist otherwise than with and in its countless modifica tions. God then exists only in things as their universal essence, and they only in him as the modes of his reality. In this sense Spinoza adopts from Nicolaus Cusanus and Giordano Bruno the expressions natura naturans and natura naturata. God is Nature : as the universal world-essence, he is the natura naturans; as sum- total of the individual things in which this essence exists modified, he is the natura naturata. If in this connection the natura naturans is called occasionally also the efficient cause of things, this creative force must not be thought as something distinct from its workings ; this cause exists nowhere but in its workings. This is Spinoza's complete and unreserved pantheism.
Finally this relation is repeated yet again in the distinction which Spinoza establishes between the infinite and the finite modes. ' If each of the countless finite things is a mode of God, the infinite connection or coherence which exists between them must also be regarded as a mode, and, indeed, as an infinite mode. Spinoza affirms three of these. 4 The deity as the universal world-thing appears in individual things, which are finite modes ; to them corresponds as
1 To this"corresponds also hla theory of cognition with its three stages, which sets intuition," u the immediate apprehension of the eternal logical remitting of all thing* from God, an knowledge sub specie aeternitatis, above perception and the activity of the intellect.
* which, however, is in nowise to be interpreted aa if the attributes were •df-aabflistent prime realities and "God" only the collective name for them (a* K. Thomas supposed, Sp- ats itetaphy Biker, Konigxberg, 1840). Such a rraaaly nominalistic cap-stone would press the whole system out of joint.
» Ktk. I. 23 and 30 ff. « Sp. 64 (Op. II. HV).
410 The Renaissance : Natural Science Period. [Part IV.
infinite mode the universe. In the attribute of extension the finite modes are the particular space-forms ; the infinite mode is infinite space, or matter ' itself in its motion and rest. For the attribute of consciousness, the intellectus infinitus1 stands beside the particular functions of ideation and will. Here Spinoza reminds us imme diately of the realistic pantheism of David of Din ant (cf. § 27, 1). His metaphysics is the last word of mediaeval Realism. '
6. With these motives relating to the problem of the qualitative difference of substances modern philosophy struggled out of its dualistic presuppositions to a monistic adjustment ; but at the same time, still more powerful motives became mingled in the process, — motives which grew out of the real and causal separation of the spatial and the conscious worlds. At first, indeed, it was the principles of mechanics themselves which demanded the attempt to isolate completely the course of events in each of the two spheres of finite substances.
This succeeded in the corporeal world in a relatively simple manner. In this domain, the idea of cause had acquired a completely neiv significance through Galileo. According to the scholastic con ception (which even in Descartes' Meditations, in a decisive passage, was still presented with axiomatic validity) causes were substance* or things, while effects, on the other hand, were either their activities or were other substances and things which were held to come about only by such activities : this was the Platonic-Aristotelian concep tion of the oitux. Galileo, on the contrary, went back to the idea of the older Greek thinkers (cf. § 5), who applied the causal relation only to the states — that meant now to the motions of substances — not to the Being of the substances themselves. Causes are motions, and effects are motions. The relation of impact and counter-impact, of the passing over of motion from one corpuscle to another,* is the original fundamental form of the causal relation, the form which is clear to perception or imagination (anschaulich), is intelligible in
1 Tins equivalence holds good with Spinoza as well as with Descartes.
2 This intellectus infinitus appears again in the ethical part of the Spinozistic system as amor intellectuals quo deus se. ipsum amat. In both cases Male- branche's " raison universelle " amounts to the same thing.
8 Geulincx also, in a mauner similar to that of Spinoza and Malebranche, regards finite bodies and minds as only "limitations," " prcecisiones " of the universal infinite body and the divine mind. Cf. Met. p. 56. If we think away limitation from ourselves, he says, ib. 237 ff. , there is left — God.
4 Hence for Descartes the mechanical principle excluded possibility of action at a distance, just as it excluded empty space. This forced him to the artificial hypotheses of the vortex theory, by which he aimed to give a physical ground for the Copernican view of the world (popular exposition by Fontenelle, Entretiens sur la Pluralite des Mondesi 1686). The grounds on which this doctrine was displaced by the Newtonian theory of gravitation are no longer philosophical, but purely physical in their nature.
Chap. 2, $ 31. ] Substance and Causality : Galileo, Descartes. 411
itself, and explains all others. And the question as to the nature of this fundamental relation was answered by the principle of math ematical equality, which, in turn, passed over into that of metaphysi cal identity. So much motion in the cause, so much in the effect also. Descartes formulated this as the law of the conservation of motion in Nature. The sum of motion in Nature remains always the same : what a body loses in motion it gives to another. As regards the amount of motion, there is in Nature nothing new, especially no impulse from the spiritual world. ' Even for the king dom of organisms this principle was carried through, at least as a postulate, though as yet with very weak grounds. Animals, also, are machines whose motions are evoked and determined by the mechanism of the nervous system. Descartes thought of this mechanism more precisely (and with him Hobbes and Spinoza) as a motion of finest (gaseous) substances, the so-called spirit us ani- males,* and sought the point of transition from the sensory to the motor nervous system in man, in a part of the brain which has no correlative, i. e. is a single and not a j>aired organ, the pineal gland or eonarium.
The other part of the task proved much more difficult : namely, that of understanding the mental life without any relation to the corporeal world. Easy and clear to perception as was the action of one body upon another, it did not yield a mode of representing an incorporeal connection between different minds, that could be used scientifically. Spinoza, for example, expressed the general meta physical postulate very energetically, when he promised in entering upon the third book of the Ethics, that he would treat the actions and desires of man as if lines, surfaces, and bodies were the subject of discussion ; for the important thing is neither to asperse them nor to deride them, but to understand them. But the solution of this problem was limited in advance to investigating the causal connec tion between the activities of consciousness in the individual mind : dualism demanded a psychology free from all physiological constitu ents. It is all the more characteristic of the predominance of the spirit of natural science in the seventeenth century, that it attained this psychology demanded by the theory, only in the most limited degree. And even the beginnings toward this are ruled by the endeavour to apply the methodical principle of mechanics, which
1 Henoe Hobbes excluded from physics the Aristotelian and ThomUtic concep tion of the unmoved mover, while Descartes, who in this point also proceeded mure metaphysically, made motion to have been communicated to matter at the beginning by God.
* An inheritance from the physiological psychology of the (ireeks, in particu lar from that of the l'eripatetics.
412 Tlie Renaissance: Natural Science Period. [Part IV.
was celebrating its triumphs in the theory of outer experience, to the comprehension of the inner world also.
For just as the investigation of Nature from Galileo to Newton directed its energies toward finding out the simple fundamental form of corporeal motion, to which all complex structures of outer experience could be reduced, so Descartes desired to establish the fundamental forms of psychical motion, out of which the multiplic ity of inner experiences would become explicable. In the theoreti cal domain this seemed attained by establishing the immediately evident truths (the innate ideas) ; in the practical field there grew out of this demand the new problem of a statics and a mechanics of the movements of feeling (Gemuthsbewegungen) . In this spirit Des cartes and Spinoza produced their natural history of the emotions (Affecte) and passions,1 the latter author by combining the thoughts of the former with those of Hobbes. Thus Descartes derives the whole host of particular passions, as species and sub-species, from the six fundamental forms of wonder (admiratio), love, and hate, desire {disir), pleasure and pain [or joy and sadness, Lust und
Unlust~\ (lostitia — tristitia) ; thus Spinoza develops his system of the emotions out of desire, pleasure, and pain (appetitus, Icetitia,
by pointing out the ideational processes in connection with which these emotions have become transferred from their original object, the self-preservation of the individual, to other " ideas. "
A peculiar side-attitude is taken in this regard by the two English thinkers. For Bacon and Hobbes, a mechanical conception of the mental is the more natural in proportion as they endeavour to draw the mental more closely into the circle of the physical. Both, that regard the empirical psychical life, and therefore, also, the sphere of consciousness which in Descartes' system was to have nothing to do with the corporeal world, as something which essen tially belongs thereto on the other hand, there set over against the whole world of perception rather something spiritual [spirit ual in the religious sense, Geistliches'] than something mental or intellectual [Geistiges]. Ideas and volitions as they are known by experience are held to be at bottom activities of the body also, and
besides these we speak yet of an immortal soul (spiraculum), of spiritual world and of the divine mind or spirit, this should fall to the province of theology. But according to this view the natural science theory cannot be characterised much otherwise than as an
Descartes, Lts Passions de VAme Spinoza, Eth. III. , and Tract. Brev. II. fl. Cl. below, No.
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