A Brief History of Modern Philosophy/Book 2


the great systems

The new interests, viewpoints, and discoveries of the Renaissance naturally gave rise to a desire to elaborate a new world-theory, one which would be inherently consistent and at the same time conform to the new thought. It was but natural that men should be anxious to follow the new ideas to their ultimate consequences. The human mind always shows a certain tendency, more or less pronounced, towards the systematization of knowledge into a unitary theory, and the more peaceful period which followed the turmoil and strife of the Renaissance furnished a splendid opportunity for the development of this tendency. It assumed the task of combining the new worldview and the new science with the philosophy of mind or spirit. Here Bruno had prepared the way. He had not however completely grasped the new scientific method. He was unable to apply the mechanical conception—by means of which a multitude of problems can be stated with far greater precision—to the statement of his problem.

Of the four fundamental problems of philosophy, the problem of Being now takes first rank. Compared with this, other problems, despite the fact of their frequent and perplexing obtrusiveness, fall into the background. The constructive method was courageously applied to the solution of the profoundest problems of human thought. Descartes, the first of the group of the great systematizers, both in his preliminary essays as well as in the later more positive statement of his theory, still reveals a distinct effort to pave the way for speculative construction by means of exhaustive analysis. But with Hobbes and Spinoza the constructive element is predominant. The only way we can discover the facts and analyses by which these thinkers established their definitions and axioms is by a less direct method. In Leibnitz, the fourth and last of the group, the analytic method becomes more prominent again. He marks the transition to the eighteenth century, in which the problems of knowledge and of values acquire an exceptionally prominent place.

The increasing favor of the constructive method of this period is closely paralleled by the dogmatic character of these intellectual efforts. The principles of the mechanical theory of nature were regarded as absolute, objective truths. Leibniz likewise shows some divergence from his predecessors on this point, by the fact that he subjects even these “primary and real” attributes of things, which were regarded as absolute data in the mechanical theory of nature, to a critical analysis.

a. René Descartes (1596-1650) may be called the real founder of modern philosophy. He was the first to inquire after the ultimate presuppositions of knowledge, and his theory was the first to take explicit account of the mechanical explanation of nature in the statement of the problem. He applies the analytic method in searching for ultimate principles, but he quickly abandons it for the constructive method, because he believes it possible to demonstrate the necessity and rationality of the principles of the mechanical theory of nature. He regards the idea of God, the validity of which he demonstrates by the speculative method, as an absolute terminus of reflective thought. Descartes thus presents a peculiar combination of keen analysis and dogmatic assertion. Descartes was the son of a French nobleman, and his economic independence furnished him the opportunity of devoting himself wholly to meditation and scientific research. His Discours de la methode (1637) is an interesting philosophical autobiography. He received his education at a Jesuit College, but, notwithstanding the fact that he had among his tutors the best teachers of his age, he was very much dissatisfied with his acquirements when he had finished his studies. He knew many things, but a consistent system and clear fundamental principles were lacking. He was particularly fond of mathematics but it seemed to be nothing more than a fiction of the human brain. He finally plunged into public life, trying one thing after another, but was invariably driven back to his solitude by his insatiable thirst for knowledge. He finally resolved to make a first hand study of practical life in the army and the courts of the nobility. But at every venture he returned again to quiet meditation. During the winter of 1619, while in camp with the army of the Elector of Bavaria, he experienced a scientific awakening. In a moment of intellectual enthusiasm a plain way of escape from his doubt appeared to him. If we begin with the simplest and clearest ideas and pass step by step to the more complex problems, the confusing multiplicity of our ideas will vanish. We can then arrange our thoughts in such an orderly manner that the successive steps can always be deduced from their antecedents. He followed this principle both in his mathematical and in his philosophical investigations. After several years of study in Paris he returned to Holland, where he believed he could pursue his investigations with less danger of disturbance. There is no doubt however that the severe injunctions against antischolastic theory formed part of his motive for leaving France. But even in Holland he became involved in controversies, because both Protestant and Roman Catholic theologians regarded his philosophy with suspicion. At the invitation of Queen Christina he spent his last years in Sweden.

1. Descartes, who was a great mathematician himself (founder of Analytical Geometry), attributed the distinction between geometry and philosophy to the fact that the former is based upon principles concerning which there could be no room for doubt, whilst the controversies in philosophy pertain to these very principles. The discovery and establishment of first principles require the use of the analytic method, i.e. we must proceed from the given or the provisionally established to its presuppositions. Analysis finally leads to simple intuitions, and these in turn originate directly through experience. The subjective movements of intellect are of this sort, e.g. that a triangle is bounded by three lines—that a thing cannot both be and not be at the same time,—that everything has a cause, —that the effect cannot be greater than its cause,—that I must exist if I think (Régles pour la direction de l’esprit, evidently written 1628-1629). He called these processes simple intuitions, and afterwards made the last one mentioned the basis of his theory (in the Discours and in the Meditationes which appeared in 1641). It is possible to doubt every idea or object of knowledge; all our perceptions or postulates might be illusory. But doubt has a definite limit. Even the most radical doubt presupposes thought. Thought is a reality even though all of its conclusions should be illusory. Descartes takes the word thought in its broadest sense: thought is everything which goes on in consciousness. When, in the language of his famous proposition, he says: Je pense, donc je suis! (Cogito, ergo sum!) he might as well have said: Je sens, je veux, donc je suis!—The word “therefore” (donc, ergo) is inexact; for Descartes does not regard the proposition as a logical deduction, but as an immediate intuition, a simple intellectual step, through which we become conscious that we are conscious.—The clearness and distinctness of this intuition, according to Descartes, furnish the criterion by which to test other propositions. There are two more intuitions however which he thinks are just as clear and self-evident as this first one, namely the proposition that everything has a cause, and that the effect cannot be greater than the cause.

If we examine our different ideas, we find that some of them can be attributed to external and finite causes, and that others are produced by ourselves, but that there is one idea which presupposes an infinite cause—namely the idea of God. I am myself (which is proved by the fact that I can doubt) a finite, imperfect being, and I cannot therefore have formed the idea of an infinite, perfect being. This idea must have its origin in an infinite being. This is the only possible explanation of the fact that my intellect, as soon as it has attained mature development, forms this idea. It is “innate,” not indeed as if it were consciously present at the very beginning of life, but in the sense that there is a disposition to form it in the very nature of the intellect.—Descartes however has another proof of the existence of God: God, the perfect Being, must exist; for existence is perfection, hence the denial of the existence of God would be self-contradictory. This is the so-called ontological proof, which finds the warrant for the existence of God in the concept.

It is only after Descartes has established the validity of the idea of God (assuming the principle of causality as a matter of course) that he has a secure foundation for the validity of knowledge in general: for a perfect being cannot deceive.

Descartes bases the knowledge of reality on the idea of God, just as Kepler had explained the conformity of nature to mathematical principles on theological grounds. But, in that case, God is merely an explanation of the sublime uniformity of natural phenomena, rather than a specifically religious concept. Thus, e.g. in the sixth meditation, he says, “By nature in general (natura generaliter spectata) I simply mean God himself or the order and disposition instituted (coordinatio) by Him in created things.” Everything which is to be accepted as true must fit into this great system. The criterion by which we are able to distinguish between dream and wakeful consciousness consists in the fact that the various experiences of wakeful life can be coordinated with our total experiences and recollections without a break in the system.—Descartes had not observed that this criterion was already contained in the causal principle, so that he might have spared himself the indirect route through the idea of God. The establishment of this criterion furnished the basis of a new conception of truth, according to which truth consists of the internal relation of perceptions and ideas, instead of their harmony with something unperceived.

Descartes is fully aware that the idea of God, which he makes the foundation of all science, is not the popular one. He says that when God is conceived as a finite being, receiving honor from men, it is not strange that His existence should be denied. God is however the absolute Substance, i.e. a being, which exists through itself (per se), requires no other being, in order to exist. It is true, Descartes likewise employs the concept of substance in reference to finite things (e.g. matter and the soul); he says however that the concept cannot be used univocally (univoce) of infinite and finite being, because finite beings are always dependent and the term substance is therefore applied to them inexactly. According to the broader, inexact linguistic usage, “Substance” means the same as thing or being, the subject or matter or substrate of given attributes.

2. The idea of God not only guarantees the reality of things, but it is likewise the source of the fundamental principles of natural science. (Principia Philosophiæ, 1644.)

Our sense impressions serve the purpose of guiding us in practical activities. In order to do this they need not be like the things themselves, if only they correspond to them. When we come to think of the real nature of things apart from our sensations, there are only three attributes which are incontrovertible: extension, divisibility and mobility. We cannot even in imagination think these attributes away. And these three attributes furnish the basis of the simplest and clearest understanding of everything that takes place in the material universe, whilst qualities merely furnish illusory explanations. All the attributes of nature may therefore be referred to extension, divisibility and motion. Qualities however are simply to be ascribed to the perceiving subject.—Descartes thus deliberately systematizes the mechanical conception of nature. He seems to have been led to this conclusion by his studies in natural science during the years 1620-1629, independent of Galileo, although perhaps influenced by Kepler.

He derives the first principles of the mechanical conception of nature from the concept of God. As perfect being God must be immutable. The idea of anything which He has created being capable of changing its state without some external cause contradicts this immutability. Material things cannot therefore on their own account (sua sponte) without external interference (of another material thing) pass from motion to rest or vice versa. (Descartes nevertheless makes a reservation in the interest of his spiritualistic psychology, namely that it is perhaps possible for souls or angels to act on matter.) Besides inertia, Descartes likewise deduces the constancy of motion (an imperfect antecedent to the persistence of motion) from the unchangeableness of Deity. Conservation (which, according to Descartes, consists of an incessant continuance of creative activity) implies that the sum total of motion implanted in matter at creation must remain unchanged. The distribution of motion among the various parts of the universe may vary, but no motion can be lost and no absolutely new motion arise.

Descartes regards the teleological explanation of nature, which accounts for natural phenomena from the viewpoint of ends, as inapplicable. He bases his rejection of final causes on theological grounds. Since God is an infinite being, he must have purposes beyond our power to conjecture, and it were therefore presumption on our part to suppose it possible to discover the purposes of natural phenomena. There are likewise many things in the finite universe which do not affect us in the least,—what sense could we therefore ascribe to their having been created on our account!—The teleological explanation is therefore rejected, because it is too narrow.

Descartes undertakes a detailed explanation of nature on the basis of the principles thus established. He differs from Bacon at this point in the importance which he attaches to deduction, and from Galileo (whose importance he decidedly underestimates) in his inability to combine deduction and induction in the investigation of the facts of experience. He regards experience as nothing more than occasional, because he thinks that science can only give the possible, not the real, explanation of phenomena. He aims to restrict himself to hypotheses, and he does not even attempt to verify these hypotheses. His natural philosophy thus assumes an abstract and arbitrary character. His importance rests on the ideal of natural science which he proposed: namely, to deduce phenomena from their causes with mathematical necessity. He therefore took no account of anything but the geometrical attributes of things, and he treated the concepts of matter and extension as identical. He substituted this ideal of knowledge for the prevalent scholastic method of explanation, based on qualities and hidden causes.

Descartes attempted to explain the existing state of the Universe by mechanical processes of development. He assumes a primitive condition in which the particles of matter exist in whirling eddies (vortices) with fixed centers. The smaller particles, resulting from the mutual friction of the larger particles, were compelled to congregate around these centers, and thus formed the various world-bodies. Some of these bodies, like the earth, have lost their independence, because they are carried along by the more powerful cycles in which the great world-bodies are found. Weight consists of the pressure due to the rotary motion, which drives the smaller particles into close proximity to the larger bodies.—In suggesting this theory, imperfect as it is, Descartes anticipated Kant and Laplace.

Organisms, as well as the World-all, are to be regarded as machines. If physiology is to become a science, it must be mechanics. The organism must be subject to the general law of matter. Harvey’s discovery of the circulation of the blood (1628) strengthened Descartes’ conviction. Descartes did much to suppress the fruitless theory of vitalism which explained organic phenomena by the assumption of a specific vital energy. In the department of nerve physiology, like Harvey in the doctrine of the circulation of the blood, he is a pioneer because he was the first to describe what is now called reflex action, i.e. muscular activity resulting directly from an objective stimulus without the intervention of any attendant consciousness. Descartes ascribed consciousness to man alone; he regarded animals as mere machines.

The human soul interacts with the brain, or, to be more exact, with a distinct part of the brain (the pineal gland, glandula pinealis), which, in Descartes’ opinion, was centrally located, and it does not consist of pairs, like the other parts of the brain. The “vital spirits” (the delicate fluid, which, according to the physiology of the age, inherited from antiquity, pours through the nerves) strike this pineal gland and the impact translates it to the soul, thus giving rise to sensations. If the soul on the other hand strikes the pineal gland it can produce changes in the tendencies of the “vital spirits” and thus give rise to muscular activity.—Here Descartes contradicts his own doctrine of the persistence of motion; for if the pineal gland strikes the soul, a loss of motion must result, and, conversely, if the soul excites motion in the pineal gland, new motion must arise. He of course limits the action of the soul to the mere matter of producing a change of tendency; but this requires him to postulate an arbitrary exception to the principle of inertia.

Descartes places great stress on the distinction in defining the soul as thinking being, and matter as extended being. Their fundamental attributes are so different that they must be called two different substances, and moreover in the full sense of the word, since it must be possible for the one to exist without the other. But, in that case, their interaction becomes an impossibility; for Substance, strictly speaking, cannot be acted on from without.

In his special psychology (particularly in his interesting treatise on the emotions, published in his Traité des passions, 1649) he endeavors—in harmony with his dualistic theory—to furnish a separate definition for the mental phenomena which have a psycho-physical basis from those which are purely psychical. Hence he makes a distinction between sensation and judgment, sensory and mental recollection, imagination and intellection, desire and will, affections (passions) and emotions (émotions intéreures). His precision at this point is rarely equalled even by spiritualists.

Descartes’ ethics bears an interesting relation to his world theory. He elaborated the details of this phase of his theory in his correspondence with Princess Elizabeth Christina of Sweden, and Chanut the French ambassador to Sweden.—He emphasizes the cultivation of the subjective emotions, rather than the “passions” which depend on external influences. But improvement in knowledge is likewise of great value: we discover that everything depends on a Perfect Being; we find that we are but infinitesimal parts of an infinite world, which cannot have been created on our account. We finally come to regard ourselves as parts of a human society (Family, State), whose interests take precedence over our private interests. It is important above all else to distinguish between what is within our power and what is not. The highest virtues are magnanimity (generosite) and intellectual love towards God (amor intellectualis dei). The latter is capable of governing our whole life, even though in the eyes of the theologians it should perhaps be regarded as insufficient for salvation.

Cartesianism was the first form in which the thought of the new age became accessible to wider circles. Notwithstanding his hypotheses, which were frequently unfortunate, his rigid insistence on a mechanical explanation of nature marks a distinct advance, and his labors inspired a vigorous movement in the department of natural science. His spiritualism and his attempt to combine theology and science developed a sympathetic attitude towards religion, notwithstanding the fact that many theologians, to whom a criticism of scholasticism was identical with a challenge of faith, were fanatically opposed to him. The clearness with which he expressed his views admitted of easy popularization, and, after the first opposition subsided, he acquired a large following in France, Holland and Germany.

Descartes however bequeathed profound problems to his successors. How can the existence of an absolute Substance be reconciled with the independent existence of particular things (souls and bodies)? And how shall we conceive the interaction of spirit and matter if both are to be regarded as independent beings (Substance), and this moreover if the principle of the persistence of motion is likewise to be maintained!

Occasionalism, so called, which had a tendency to refer all true causality to the absolute essence, so that the states of finite beings merely furnished the “Occasions” for God to interpose, was the logical result of these problems. This principle was at first only applied to the relation of spirit and matter: what takes place in the body furnishes God the occasion to permit a change to take place in the soul, and vice versa. It soon became evident however that, if there is an absolute substance, it is impossible for a finite being to be a cause at all. How can anything produce an effect beyond its own being in some other thing? Not only the interaction between spirit and matter but all interaction between finite beings is impossible, and divine causality alone remains possible. In this way first the psycho-physical problem and then the problem of causality conceived as a whole came to be regarded as insoluble and philosophy resolved itself into theology.

After a number of Cartesians had prepared the way for this conception, it was clearly and definitely elaborated by Arnold Geulincx (1623-1669) and Nicholas Malebranche (1648-1715).

Geulincx, originally a Catholic (he was born at Louvain), but later a convert to Protestantism, experienced a vigorous opposition both from Protestant as well as from Catholic scholasticism on account of his Cartesianism. During his latter years he occupied the chair of philosophy at the university of Leyden. His most characteristic work is his ethics (1665, complete 1675). In order to do right, man must learn to understand his position in the world; self-examination (inspectio sui) is therefore the foundation of ethics. It reveals the fact that intellect and will are all that really belongs to my Self. My body on the other hand is a part of the material universe where I can accomplish nothing. For I am only responsible for the things of which I can know the origin, and this knowledge is limited to my intellect and will. My activity cannot transcend my essential nature (i.e. my intellect and will). It is utterly impossible for a thing to produce changes beyond itself and its own states. If the changes of one being (e.g. the soul) correspond to the changes in another being (e.g. the body), it can only be explained by the fact that their common author forever adapts them to each other—like two clocks which a clockmaker is constantly regulating in successive order (a figure used already by the Cartesian Cordemoy).—The ethical system which Geulincx elaborates on this foundation consistently assumes the character of resignation, and its chief virtue is humility. For, where I am unable to do anything, it is sheer folly that I should desire (ubi nihil vales, nihil velis!).

Malebranche, a member of the Oratory, gives the mystic phase of occasionalism still greater prominence. His philosophic inspiration came from one of Descartes’ books, and it permeated his entire life, which was spent in the cloister. The senses—as appears in his Recherche de la verité (1674ff)—are given us for practical purposes and they are unable to discover the real nature of things. The senses deceive us every time we are misled into ascribing sensible qualities to things themselves. Whence therefore do we get knowledge of things? The understanding is quite as incapable as sensibility to teach us anything about things which exist independently of us. Neither we ourselves nor things can produce knowledge, for no finite being can create anything new. Causation is a divine thing, and it is pagan to ascribe causality to finite beings. Finite beings forever remain simply causes occasionelles. We can neither regard the motions of matter nor the thoughts of men as causes. God could not even give a finite being the power to be a cause, for God cannot create gods. Our knowledge is entirely the work of God; we see everything in Him. It is only through his interposition that we get ideas of material things. Each idea is really a limitation of the idea of God.

Joseph Glanvil (1636-1680), of England, had even prior to this defined the problem of causality in his Scepsis Scientifica (1665), a book which was influenced by the philosophy and the natural science of Descartes. The greater the difference between cause and effect the less do we understand their connection. Causality cannot as a matter of fact be conceived at all (causality itself is insensible). Our perception is invariably limited to the fact that two things succeed each other.

Glanvil and the Occasionalists are the antecedents of Hume. There are two additional thinkers who are strongly influenced by Descartes, who however, each in his own way, are radically opposed to him, and in fact challenge every attempt to solve ultimate problems with the aid of reason.

Blaise Pascal (1623-1662) is closely related to Descartes in his conception of scientific method, and he likewise accepts his concise distinction between mind and matter. He makes frequent reference to these ideas in his Pensées. But philosophy could not wholly satisfy him. His heart longed for a living God, finally even for a God of flesh and blood, despite the fact that faith in such a God was repulsive to the understanding. He required such a faith as this to subdue the fear which the thought of the eternity of the world had kindled within him. The ideas of Bruno and Böhme failed to give him peace. Knowledge is uncertain, and the learned are at variance. Reason refutes the dogmatic philosophers, nature the sceptical philosophers. As a matter of fact in the last analysis the sceptics are right; otherwise were revelation unnecessary. In reply to those who find it difficult to subordinate reason to faith, Pascal applies the Cartesian psychology and says: We are machines as well as mind; begin with the machine, accustom yourself to the ceremonies, and your mind will also finally yield.

Pierre Bayle (1647-1706) was rather a man of letters than a philosopher. His interest consisted in explaining and interpreting literary productions and speculative opinions in their manifold variety. But his desire for clearness impelled him to distinguish sharply between the various standpoints and to emphasize the crux of the problems rather than any illusory solution. (Dictionnaire historique et critique, 1695 ff.) He was particularly opposed to all efforts to reconcile faith and knowledge, theology and philosophy. He regarded the problem of evil as the great rock of offense. If we resolutely follow reason, it is impossible to reconcile the reality of evil with the omnipotence and goodness of God, and the only consistent solution that remains is the Manichæan assumption of two world principles, one evil, the other good. We are obliged to choose between reason and faith. (Dictionnaire Art. Manicheisme.—Response aux questions d’un provincial.) He nevertheless believes in a natural basis for ethics, and, furthermore, because the actions of men are determined more by their nature than by their religious opinions, he was in position to defend toleration and religious freedom with great zeal. (Pensées diverses a l’occasion de la comète.)

2. Thomas Hobbes (1588-1679) made the first independent attempt to treat the new mechanical theory of nature as the only science, to maintain its viewpoints as the only ones from which reality is to be conceived. Energetic as a thinker and controversialist, mild and timid in his mode of life, Hobbes, like Descartes, was dissatisfied with his scholastic training, and hence devoted himself to literary pursuits,—e.g. he published a translation of Thucydides. The unsettled conditions in England aroused his interest in political and ethical questions, which soon led, especially after he became acquainted with the new viewpoints of natural science, to general philosophical investigations. For a while he was private tutor and afterwards an intimate friend of the noble family Cavendish. While travelling in Italy he made the acquaintance of Galileo, and in France he became a friend of Pierre Gassendi (1592-1655), likewise an admirer of Galileo, who, having resigned his clerical position, was then living in Paris as professor of mathematics. In his philosophical thought Gassendi reveals a philosophical tendency similar to that of Hobbes (Opera Omnia, Lugd., 1658). His revival of the Epicurean atomic theory became a matter of signal importance, for it was from the writings of Gassendi that Newton became acquainted with this doctrine, and Dalton, the chemist, afterwards received it from the writings of Newton and adapted it to chemistry. Gassendi insisted that all the changes in nature must be explained by the motions of atoms. Following Galileo, Gassendi teaches (what Descartes had overlooked) that energy (impetus) is not dissipated by actual motion.

Nevertheless, Hobbes seems to have arrived at the conclusion that all change is motion independently. It was during a discussion with several friends of what constitutes sensation that the thought occurred to him that if everything in nature were motionless or in uniform motion there would be no sensation. A change of motion (diversitas motuum) is therefore the condition of sensation. For sensing unceasingly one and the same thing and sensing nothing at all amounts to the same thing. This principle, which Hobbes makes the basis of his psychology, occurred to him early in life, and the conviction that all change consists of motion, and that sense-qualities are purely subjective, probably occurred about the same time (ca. 1630), at any rate before his acquaintance with Galileo and Gassendi.

At the outbreak of the revolution Hobbes left England and spent a number of years in France, where for a time he was tutor to the fugitive king Charles II. He returned under Cromwell, devoting himself privately to literary pursuits, occupied with studies and polemics until his death at the venerable age of ninety-one years. The series of articles and the splendid volume in Fromann’s Philosopische Klassiker by Ferdinand Tönnies have contributed much towards a clear understanding of Hobbes’ development and his philosophical significance.

Hobbes’ chief works are: Elements of Law (1640), De cive (1642), Leviathan (1651), De corpore (1655), De homine (1658).

a. Hobbes’ first concern in the systematic presentation of his theory given in the De corpore is to establish the fundamental principles of investigation. He is certain that these principles must be discovered by a process of analytical regression from the given to that which explains it (a sensum ad inventionem principiorum), just as he had previously in fact arrived at the doctrine of motion by a similar regression from sensation. But, on the other hand, he strongly emphasized the fact that the assumption of principles is purely an arbitrary matter, and must necessarily consist of a choice. He does not therefore regard such an analysis as a demonstration; deduction is the only method of demonstration, and this is impossible in the case of first principles.—Hobbes described the arbitrary act with which science begins more precisely as an act of naming. But this act is subject to certain conditions even from its very beginning; it is not permissible therefore to give two contradictory names to one and the same thing.

That all change consists of motion (mutationem in motu consistere) is therefore the most general principle of science. Hobbes thinks that, if we should only rid ourselves of all prejudices, the proof of this principle is wholly superfluous. He assumes several other, purely dogmatic, principles, without inquiring more closely into their respective conditions; the law of causation, the principle of inertia, the principle that only motion can be the cause of motion, and that only motion can be the result, and the principle of the persistence of matter.

If these principles are to explain all existence, then everything must be motion. The classifications of the system are therefore based on a classification of motion. First in order comes the theory concerning the Corpus (body in general); here he treats of the geometrical, mechanical and physical laws of motion. The second part contains the theory of the Homo, i.e. the motions which take place in Man; here the physiological and psychological motions are treated. The third part is the doctrine of the Cives, i.e. of the motions in men which condition their mutual relations and their association.

Hobbes was unable to complete his system by purely deductive processes. He was forced to concede the necessity of introducing new presuppositions at a number of points. Thus, e.g. when we pass from geometry to mechanics: Hobbes grants, that a pure geometrical explanation rests on an abstraction, and that we must assume the concept of energy (conatus, impetus) at the beginning of mechanics. The same is true when we pass from mechanics to physics: the sensible attributes of body (color, tone, etc.) are discovered only by means of sense perception, which involves a new inductive beginning at this point. And the last two main divisions of the system, the theories of the Homo and the Cives, we can establish by direct (psychological and historical) experience, without going through the first main division. Hobbes also wrote his psychological and political works (Elements of Law, De cive, Leviathan) before he had completed his theory of the Corpus.

If everything is motion, all reality must be corporeal. An incorporeal thing is a chimera (Unding). It follows therefore that science can only investigate finite things, since only finite things can be in motion. It is impossible to have any knowledge of the universe as a complete whole. All questions concerning the universe as a totality lead into the inconceivable and can only be determined by faith, not by knowledge. Science can tell us nothing concerning either the origin, extent or destiny of the universe. The highest science, the firstlings of wisdom (primitia sapientiæ), Hobbes remarks ironically, are reserved to the theologians, just as in Israel the firstlings of the harvest were sacrificed to the priests.

b. Hobbes started with sensation; from it he derived the principle of change, and thence the principle of motion. If everything is motion, therefore, sensation must likewise be motion. “Sensation is nothing more than a motion among the particles of the sensing body.” And this applies to consciousness in general. In his criticism of Descartes’ Meditations Hobbes says “Consciousness (mens) is nothing more than a motion in certain parts of an organic body.” Motion is the reality, consciousness is only the form under which it becomes apparent ( apparition). The feeling of pleasure, e.g., is really only a motion in the heart, thought only a motion in the head. The psychology of Hobbes is therefore merely a part of his general theory of motion. His materialistic tendency which is apparent at this point is modified by his clear insight into the subjective conditions of knowledge. In a remarkable passage (De corpore, xxv, 1) he says: “The very fact that anything can become a phenomenon (id ipsum) (το φαινεσφαι) is indeed the most wonderful of all phenomena.” The fact that motion can be conceived, sensed, known, is therefore more wonderful than that it exists. The conception, the “apparition,” then cannot itself be motion, but must be an evidence that there is still something else in the universe besides motion.

Sensation, memory and comparison are intimately related to each other. If the sensory stimulus vanishes, instantly, there is in fact no sensation (sensio), but only a vague impression (phantasma). Real sensation presupposes a distinction and comparison of such impressions. The sensory stimuli must therefore vary, in order to make sensation possible.—Memories follow certain laws: they reappear in the same order of sequence as the original sensations, unless disarranged by the feelings and impulses. All order and every definite relation governing our ideas (except our temporal order of sequence) are conditioned by the fact that we are actuated by a purpose and seek the means for the realization of that purpose. The constant fixation of our purpose (frequens ad finem respectio) brings system into our thoughts. The capriciousness of dream-ideas is explained by the absence of a constant purpose during sleep.

He derives all individual feelings and volitional experiences from the impulse of self-preservation. Pleasure and pain arise according as our organic life is fostered or suppressed. Every movement and every idea which is favorable to the persistence and advancement of life is conserved; detrimental motions and ideas are suppressed. Here again we are confronted with the idea of change as a condition of soul-life. There can be no feeling and no will without distinctions in experience. An absolute goal, attainable once for all, is unthinkable. If it were attained, the possibility of a wish or of effort would no longer exist and feeling would likewise be impossible. The greatest good can consist only in an unhindered progress towards ever higher goals.

The various forms of feeling and of desire appear as expressions of a feeling of power or of weakness. That is to say whether I feel pleasure or pain depends upon whether I am conscious of having the means of continued existence, development and satisfaction, and, as a matter of fact, it is through a consciousness of this sort that the feeling of power is conditioned by its opposite, the feeling of weakness (which can also be a dependence upon receiving help from friends or from God). Here the comparison with other men plays an important part, for my self-preservation is quite frequently favored as well as hindered by others (and their impulse to self-preservation). Life is a great race. Whenever we surpass others we rejoice, but we feel humbled when we fall behind; while we are making the best progress we are filled with hope, but doubt as we grow weary; we become angry when we see an unexpected obstacle, but we are proud when we have surmounted a serious difficulty; we laugh when we see another fall, but weep when we fall ourselves; we have a sense of sympathy when some one whom we wish well falls behind, indignation when some one whom we wish ill succeeds; love when we can assist another in the race, happiness when we are constantly overtaking those ahead of us, unhappiness when we are constantly falling behind. And the race ends only in death.

c. The human impulses of self-preservation are not primarily in mutual harmony: this is clearly manifested in the experiences of the great world-struggle. Strife will arise, and encroachments are always to be feared. The state of nature, i.e. the state of human life as it would be without state control, is a war of all against all (bellum omnium contra omnes). The sole governing principle at this stage is the unrestrained impulse and power of the individual, and fear, hatred, and the restless human passions are supreme. But in calmer moments (sedato animo) men perceive that greater advantage can be attained by cooperation and association than by strife. This gives rise to the moral principle: Strive for peace, but if peace is impossible, warfare must be organized! This principle gives rise to the special virtues and duties; fidelity, gratitude, complaisance, forbearance, justice and self-control are necessary if peace and society are to be possible. Hence the general rule, that one must not do to others what he would not suffer from them, likewise follows from this principle. But Hobbes likewise suggests that to be just towards others and to be able to give them aid (animi magni opus proprium est auxiliari) is a sign of strength and magnanimity.

But the efficient execution and maintenance of these laws and rules require a strong political organization. The freedom of the state of nature must be surrendered. This is accomplished either by an expressed or tacit contract, by which each individual at once renounces the right of his unconditioned impulse to self-preservation and pledges unqualified obedience to an established authority (a prince or a convention).—Whilst Althusius and Grotius made a distinction between the contract through which society originates and that upon which the authority of the state is founded, with Hobbes both coincide. He believes that, if the war of all against all is to be brought under control, the opposition between the governing power and the individual must be absolute, and he cannot therefore imagine that a people could exist without government. The governing power must therefore originally proceed from a decision of the people. Hobbes is the naturalistic exponent of absolute sovereignty. Every limitation (by class, parliament or church) would involve a division of power, and consequent retrogression to the state of nature. The will of the sovereign executes the will of the people and he alone (to whom indeed the natural rights of every individual are transferred in the original contract).

The sovereign must decide all questions touching religion and morality. He shall above all determine the manner in which God shall be worshipped: otherwise the worship of one would be blasphemy to another, resulting in a source of constant strife and disintegration. For the same reason, the ultimate definitions of good and evil must be fixed by the decree of the sovereign. The first principles of ethics and politics rest upon arbitrary enactment (in this case by the authority of the state).

Theoretically Hobbes anticipates the rationalistic despotism of the eighteenth century. He opposes hierarchy and class government and bases the hope of an enlightened political authority, through which the will of the intelligent public will receive recognition, on the prospect of a progressive educational development of the people (paulatim eruditur vulgis!).

3. Baruch Spinoza’s (1632-1677) chief work (Ethica ordine geometrico demonstrate, 1677) represents the most profound effort of this period to elaborate the fundamental principles of the new conception of nature into a general world theory. This work, despite its abstract form, is by no means impersonal and purely theoretical. With Spinoza, thought and life are identical. Clear thinking was for him the way to spiritual freedom, the highest form of personal life. He aims to regard all the various aspects and forms of existence from the viewpoint of internal harmony. The majesty of his thought consists, first of all, in the resolute consistency with which he elaborates the various intellectual processes, each of which, in itself, expresses an essential characteristic of reality; every essential viewpoint must receive due recognition, without prejudice and without compromise; and, secondly, in the proof that every system of thought which is inherently self-consistent and complete nevertheless signifies nothing more than a single aspect or form of infinite Being. In this way he seeks to maintain unity and multiplicity, mind and matter, eternity and time, value and reality in their inner identity. Each of these fundamental concepts is in itself an expression of the total reality and can therefore be carried out absolutely.

In his chief work, mentioned above, he elaborates this theory deductively or synthetically. Beginning with definitions and axioms we advance through a series of doctrinal propositions. Owing to this method of treatment Spinoza failed to give his own ideas their true force. Their content is not adapted to this mode of treatment, and his proofs are therefore frequently untenable. Nor does the method pursued in his treatment correspond with the method by which he discovered his theory. The unfinished treatise De emendatione intellectus is the chief source of information concerning this method. Here he begins autobiographically after the manner of Descartes in his Discours. Experience has taught him that neither enjoyment, nor wealth, nor honor can be the highest good. He finds it, on the contrary, in the knowledge of the relation existing between our mind and nature as a whole. The pleasures of knowledge became his highest and strongest ambition, his ruling passion, and the glory conferred on existence through the possibility of participating in this joy is what made life worth living to him. It is for this very reason however that he institutes the inquiry as to the possibility of realizing this end, and he then indicates how he arrived at the definitions and axioms with which the “Ethics” begins.

Spinoza, the son of a Jewish merchant of Amsterdam, began his career as a Jewish theologian, inspiring great hopes among his brethren in the faith. He however gradually became increasingly critical of the ancestral ideas of faith and was finally ceremonially excommunicated from the synagogue. Thereafter he lived in the country for a while, moving thence to Rhynsberg, in the vicinity of Leyden, and finally to The Hague, occupied with study and the writing of his books. He provided a scanty living by grinding lenses. He enjoyed the active intellectual fellowship of a circle of young friends who studied his ethics, even while it only existed in manuscript. His life is a splendid example of happy resignation and inner devotion to intellectual labor.

The essay, Von Gott, Menschen und dessen Glück, written in his youth, is Spinoza’s first attempt to bring what he regarded as essential in religious ideas into inner harmony with the scientific conception of nature. Later on he wrote an exposition of the Cartesian philosophy for one of his pupils; although strongly influenced by the writings of Descartes (together with Jewish theology and the works of scholasticism, and perhaps also by the works of Bruno) he was never a Cartesian. He likewise studied and used the works of Bacon and Hobbes.—In his Tractatus theologico-politicus (1670) he advocates religious liberty and makes some interesting contributions to the historical criticism of the various books of the Bible.

a. Our knowledge originates in incidental experience (experientia vaga). On this plane we arrange phenomena according to laws which are apparently mechanical, and we are satisfied so long as there is no exception. Science (ratio) however institutes exact comparisons of the given phenomena. It begins with experience, and then seeks to discover what belongs to nature as a whole as well as to its various parts—the universal laws, which prevail everywhere. Spinoza illustrates this by reference to the laws of motion in the realm of matter and the laws of the association of ideas in the realm of mind. It is only in these laws that our thought processes culminate, whilst the series of particular phenomena continue to infinity, because that which is cause in one relation is effect in another relation and vice versa. The only absolute which can satisfy intellect is the law which governs the causal series, not its supposed beginning or end. Spinoza calls this absolute Substance; that which exists in itself and is to be understood through itself, so that its concept presupposes no other concepts. Spinoza’s Substance, the terminus of all thought, is therefore the principle of the uniformity of Nature.

Spinoza’s discussion of the validity of knowledge is somewhat vacillating. At times he seems to hold the popular and scholastic definition of truth as the agreement of thought with its object. But when he examines the problem more closely he concludes that the perfection of knowledge consists of complete elaboration and internal consistency. He always regards error as negative, as due to the limitation of our experience and thought. Error is resolved by observing strict logical consistency; we eventually discover that we were regarding a part for the whole. Thus error finds its explanation in the truth: veritas est norma sui et falsi. Hence the norm of truth lies in the very nature of our thought, not in its relation to something external.

Knowledge of the laws of nature is however not the highest kind of knowledge. Spinoza places intuition above experientia vaga and reason. The former apprehends particular events and the latter discovers general principles, but in intuitive knowledge (scientia intuitiva) the particular phenomenon is immediately apprehended as a characteristic member of the whole system of nature, the particular being in its relation to the whole of Substance. This higher intuition is only acquired after we have passed through the stages of experience and science. Spinoza even says that he himself understood but very little in this highest manner. It appears to be more like an artificial intuition than a pure scientific conception.

We regard things from the standpoint of eternity (sub specie æterni) in the second as well as in the third form of knowledge; i.e. not in their isolation and contingency, but as members of a more comprehensive system.

b. Following Descartes and Hobbes, Spinoza bases his entire philosophy on the principle of causality, the validity of which, for him as for them, is self-evident. In his exposition of the law of causation he takes special pains to emphasize that cause and effect cannot be things which differ in kind. He says, e.g., that “If two things have nothing in common, the one cannot be the cause of the other; for then there would be nothing in the effect, which had also been in the cause, and everything in the effect would then have originated from nothing.” According to Spinoza the fact that two things are related as cause and effect signifies that the concept of the one admits of a purely logical derivation from that of the other. He does not distinguish between cause and ground. He identifies the relation of cause and effect with the relation of premises and conclusion. The fact that cause precedes effect in time, as well as in thought, finds no place in his theory. “From the standpoint of eternity” time disappears.

The cause of an event may therefore exist in the event itself or in something else. That which has its cause within itself is Substance. Substance is that which exists in itself and is understood through itself, so that its concept does not presuppose any other concept. We have already observed that Spinoza’s fundamental principle is revealed in the uniformity of nature. It is therefore the fundamental presupposition of all existence and efficiency. It follows from his definition, that it exists necessarily: it contains its cause within itself, and hence nothing can prevent its existence! Only one Substance is possible: for, if there were several, they would limit each other, in which case neither one could be understood from itself. It is likewise self-evident that Substance can neither have beginning nor come to an end, neither be divided nor limited.

This concept, which is Spinoza’s inner terminus of all thought, is at once identical with the concept of God and the concept of Nature. These concepts must then however be conceived of in a different manner than usual. Nature is the inherent energy which is active in everything which exists (natura naturans), not the mere sum of all existence (natura naturata). “I have an opinion about God and Nature,” says Spinoza, “which is different from that commonly held by modern Christians. I hold that God is the internal, not the external, cause of all things. That is, I hold, with St. Paul, that all things live and move in God.” Another divergence from the ordinary concept of God is contained in the fact that Spinoza does not think that human attributes, such as understanding and will, can be ascribed to the Deity; for understanding presupposes given experiences which shall be understood, and will presupposes that there are ideals which are as yet unrealized, each of which would contradict the absolute perfection of God.

Spinoza calls the things which do not contain their cause within themselves Modi (phenomena, individual things). The Modus is caused by something other than itself, through which alone it can be understood. The real cause of the Modi is contained in Substance, of which they are the particular manifestations. Externally they stand in a causal relation to each other, but the total aggregate of the Modi, the total series of causes and effects given in experience (the total natura naturata), is a revelation of Substance, which constitutes the vital relation of the whole series of phenomena.

c. According to Spinoza real existence can only be ascribed to Substance. Phenomena are its particular Forms. Everything which exists (Substance and its Modi), therefore, comes into experience under two attributes (fundamental characters or fundamental forms): thought and extension (mind and matter). As an infinite and perfect being Substance must have an infinite number of Attributes; but we know only two, because experience reveals no more to us. An attribute is what thought conceives of Substance as constituting its essence (essentiam substantiæ constituens). This definition implies that the whole nature of Substance must be present in every Attribute, in every fundamental form; each individual attribute must therefore, like Substance itself, be understood through itself, and its concept cannot be derived from any other concept. Everything which pertains to a given Attribute must be explained by means of this attribute alone, without reference to any other Attributes; thoughts must therefore be explained only by means of thoughts, material phenomena only by means of material phenomena. Not only Substance as such, but each of its phenomena, each Modus, e.g. man, can be regarded and explained completely under each Attribute. The nature of reality is revealed in the realm of matter as well as in the realm of mind, and the one form of manifestation cannot be derived from the other. Mind and matter (soul and body) are one and the same, only viewed from different sides.—Spinoza holds, in opposition to Descartes, that two irreducible attributes do not necessarily require two different natures, but that they can very easily pertain to one and the same nature. He differs from Hobbes in that he does not regard mind as a mere effect or form of matter, but sees in it an aspect of being quite as distinctive and primary as matter.—Descartes, Hobbes and Spinoza represent the three leading hypotheses concerning the relation of mind and matter.

Spinoza elaborates his theory of mind and matter (which in recent times has frequently been described by the unfortunate term parallelism, or the identity hypothesis) according to the deductive method, because he derives it from his definitions of Substance, Attribute and Modi. We have however already called attention to the fact that he discovered his definitions by means of the analysis of experience and of knowledge. The definition of Attribute presupposes the fundamental principle of the identity of cause and effect, previously mentioned; from this presupposition the relation between the Attributes follows in the same manner as the relation between Substance and Modi. That everything which pertains to a given Attribute must be explained by reference to that attribute is really nothing more than a metaphysical paraphrase of the principle that material phenomena can only be explained by means of material phenomena. Kepler’s vera causa makes the same demand. That this is really what Spinoza meant becomes quite apparent from the following expression: “If any one should say that this or that bodily activity proceeds from the soul, he knows not what he is talking about, and really grants that we do not know the cause of such activity.”—He nevertheless likewise calls attention to the fact that the development of the soul advances proportionately with the development of the body, and that we have no right to set arbitrary limits to the material uniformity of nature.

Spinoza does not regard the hypothesis of identity as a mere psychophysical theory. He likewise gives it an epistemological significance in that he speaks of an identity of thought with its object. Here he confuses the relation of subject and object with the relation of soul and body. This is the more remarkable, since he holds that the validity of knowledge depends on its logical consistency rather than on the agreement with its objects. But he is also somewhat vacillating on this last point, which is an after-effect of the scholastic studies of his youth.

Criticism of this most rationalistic of all systems of philosophy must first of all be directed against the central proposition of the homogeneity (or really identity) of cause and effect. Should this proposition prove untenable or even be incapable of consistent elaboration, it must follow that, in the last analysis, Being is not, as Spinoza believed, absolutely rational. We shall find this problem discussed by the English empiricists and by the critical philosophers.

d. Spinoza teaches, in harmony with this theory of error, that every idea is regarded as true, so long as it is not supplanted by another. Our theory of reality is developed through the rivalry of ideas. The most comprehensive and most consistent theory is the truest.

Spinoza’s elaboration of the psychology of the emotions as given in his “Ethics” is unsurpassed in its excellence. Like Hobbes he starts from the impulse of self-preservation. But he bases it on the consistency of his system. The infinite Substance is actively present in every individual being (modus); the effort towards self-preservation of each individual being is therefore a part of the divine activity. Hence whenever effort is successful, it produces pleasure, and conversely pain. But this only occurs in case of a transition to a more perfect or less perfect state; an absolutely changeless state would neither give rise to pleasure nor pain.—The various emotional qualities result from the association of ideas. We love what produces pleasure, and hate what produces pain. We love whatever contributes to our love, and hate what constrains it. When a being similar to ourselves experiences pleasure or pain, the same emotion involuntarily arises in us. But this moreover not only gives rise to sympathetic joy and sorrow, but it may also inspire envy and pleasure at the misfortune of others, i.e. if we ourselves wish to enjoy another’s pleasures, or if we are previously filled with hatred towards the unfortunate.—Just as pleasure becomes love by means of the idea of its cause, so mere appetite (appetitus, conatus) becomes desire (cupiditas), when joined with the idea of its object.

In Spinoza’s description of emotional and volitional life we discover a degree of vacillation between a purely intellectualistic and a more realistic (or voluntaristic) theory. In several passages he describes the emotions as confused and inadequate ideas (ideæ confusæ et inadequatæ), which vanish as soon as the idea becomes perfectly clear. But there are other passages in which the emotions are regarded as real, positive states, which can only be displaced by other real states. The same thing occurs with the concept of the will. In several passages volition is treated as one with the activity of thought; will and understanding are identical. But in other passages the will is identical with the impulse of self-preservation, and all ideas of value and value-judgments are dependent on it; “We seek, choose, desire and wish for a thing, not because we think it is good, but, inversely, we think a thing is good, because we seek, choose, desire and wish for it.” In this case therefore he asserts the priority of the will.—This vacillation is evidently (in agreement with F. Tönnies in Vierteljahrsschrift für wissenschaftliche Philosophie, VII) to be explained from the fact that, during the preparation of the Ethics, Spinoza’s older, intellectualistic conception was supplanted by a more realistic conception under the influence of Hobbes without a thoroughgoing application of the logical consequences of the new conception.

e. Spinoza bases his ethics on the instinct of self-preservation.—Man is conditioned by the fact of being one among many individual beings, and obstacles constantly thwart his instincts. As a member of the total series of causes and effects man does not contain his cause within himself, he is not active, but passive, not free, but necessitated. The sense of dependence enables man to strive for freedom and independence. He then imagines an ideal of human life (idea hominis, tanquam naturæ humanæ examplar), as it would be under conditions of perfect freedom and independence. This furnishes a standard of judgment: whatever contributes towards the realization of that ideal is good; whatever prevents it is evil. The predicates “good” and “evil” which are meaningless when applied to absolute Being, Substance, become significant from the viewpoint of temporal experience and finite development. Sub specie æterni there is no ethics; all antitheses and differences, and moreover all valuation, disappear when so considered.

A desire can be subdued only by another desire, and hence, if the ideal is to govern our life, it must either give rise to or become a desire. Duty then becomes a matter of making this desire as strong as possible. Social life is a means to this end. Men can make better provision for self-preservation by uniting their energies. Spiritual goods, especially knowledge, which furnishes the only possible means to perfect freedom and activity, can only be acquired under conditions which guarantee the external means of subsistence and this is more readily obtained in organized society than otherwise. Spiritual, unlike material, goods, which only one or a few can possess, are not the occasion of strife; they are rather the common possession of everyone, and here the individual can assist others without sustaining any loss to himself. The courageous instinct of self-preservation (fortitudo), which constitutes virtue, appears therefore not only in the form of vital energy (animositas) , i.e. as power to impress the influence of one’s personality, but also in generosity (generositas), i.e. power to lend spiritual and material assistance to others.—But the acme of spiritual freedom can nevertheless only be attained through a perfect understanding of ourselves, in our real identity with that which is most essential and highest in Being, because we conceive our own energy as a part of infinite energy and we are filled with an intellectual love for Deity brought about by the joy of knowledge (amor intellectualis dei). We then see ourselves sub specie æternitatis.

In his theory of the state, contained partly in the Tractatus theologico-politicus, partly in the unfinished Tractatus Politicus, Spinoza, like Hobbes, draws a sharp distinction between the state of nature and life within the state; but he likewise holds that it is the duty of the state to secure a greater degree of freedom and independence than would be possible in a state of nature. The individual does not surrender his liberty when he becomes a member of the state. The state is not supposed to reduce men to animals or machines, but to provide the conditions for the development of man’s spiritual and bodily functions. It would therefore contradict its office if it failed to maintain liberty of thought and speech and to guarantee complete religious liberty.

4. Gottfried Wilhelm Leibnitz (1646-1716), like his three predecessors, Descartes, Hobbes and Spinoza, is convinced of the importance of the mechanical explanation of nature. His three predecessors regarded the mechanical principles as self-evident and as given once for all, and assumed the task of interpreting the various elements of reality in harmony with the principle of mechanical causality. Leibnitz however subjects the principle of causality to a profounder analysis by inquiring into its presuppositions and seeking to refer it back to something still more fundamental. It is only after he has succeeded in this that he proceeds to the definition of the relation between matter and mind. The motive for this investigation was in part purely theoretical, due to the fact that Leibnitz discovered gaps and inconsistencies in his predecessors, in part practical, due to his desire to bring the modern explanation of nature into more perfect harmony with his religious presuppositions. He attempted to accomplish both at a single stroke, by means of a single idea, the idea of continuity.

Even as a boy, in the library of his father, who was a professor in Leipzig, Leibnitz had become familiar with the writings of Scholasticism. When he afterwards became acquainted with the natural science and philosophy of his own day he felt as if “transported into another world.” He saw that the new ideas could not be refuted, but neither could he surrender the conviction that nature is ultimately regulated by prescience, that is to say, that the mechanism must be grounded in teleology. His mathematical ideas were influenced profoundly by the physicist Huygens during a visit in Paris, and he afterwards likewise drew personally close to Spinoza. From 1676 onwards he lived at Hannover as councillor and librarian, occupied with philosophy, mathematics, history and jurisprudence. His broadly comprehensive mind was capable of engaging productively in a wide range of subjects to their material advancement. He was everywhere affected by the controlling idea of continuity, which can only be rigorously carried through by the continual discovery of more numerous and finer distinctions and nuances of thought.

a. Leibnitz discovered a difficulty in Descartes’ and Spinoza’s theory that the sum total of motion in the universe always remains constant, namely, that it fails to explain how to account for motion and rest respectively in the various parts of the universe: They exist as antithetical states! Continuity can be established only through the concept of Force (or tendency, conatus). If motion has ceased at a given point in the universe, the Force still remains and can be revived again. Motion and rest are only relatively opposed to each other. Instead of the persistence of motion we should speak of the persistence of Force. Force is the factor in any given circumstance which contains the possibility of future change. We first discover a uniform relation between two states and we afterwards call the factor in the first state which makes the second state possible Force. The concept of Force therefore rests on the concept of law, the ultimate presupposition of which is the uniform consistency of changing states. Leibnitz calls this presupposition the principle of sufficient reason.

But how shall we account for the persistence of energy? According to Leibnitz this question can be answered only teleologically. If the energy of a cause were not preserved in the effect, nature would retrograde, which contradicts divine wisdom. Leibnitz thus finds a basis for his faith in prescience in the corrected basal principle of mechanical natural science. In explaining particular facts he would apply the strict mechanical method, but the principle of mechanism itself requires the principle of teleology for its explanation.

b. Leibnitz carries his analysis further than his predecessors at still another point. They had regarded extension as a fundamental attribute of Being. Leibnitz challenges this assumption. Extended things are always manifold and complex, and the true realities are the elements which constitute things. If there were no absolute units (which cannot be extended), there would be no real existence. It is only these ultimate units that can be regarded as Substance (in its strict significance). Inasmuch therefore as Force persists, it follows that this persistent Substance must likewise be Force; it would be utterly impossible for activity to originate from Substances in a state of absolute rest. Leibnitz calls these substantial units, whose objective manifestation constitutes matter, Monads. Each Monad is a little universe; its nature is revealed in the laws which govern its inner successive changes.

What then, as a matter of fact, are these Monads? Leibnitz answers: Our souls alone furnish us with an immediate example of a unitary being, whose inner states follow a uniform law. We must think of all Monads after this analogy, because we presuppose something in all of them analogous to our sensations and activities. Since, according to the principle of continuity, we permit no leaps in nature, we must postulate innumerable grades and degrees of soul life in the universe. And this enables us to understand the origin of human consciousness. Here the Cartesians, just as in the case of the transition from rest to motion, were confronted by a riddle; for consciousness like motion cannot come into being all at once. The relation of the unconscious to consciousness is analogous to the relation of rest and motion. In order to vindicate the continuity of soul-life, Leibnitz directs attention to the fine nuances and changes of consciousness which are frequently overlooked. We are likewise obliged to postulate such minimal elements (petites perceptions) in the unconscious.

Leibnitz first elaborated this, his so-called theory of Monads, in a short essay in 1685 (Petit discours de metaphysique) and in his correspondence with Arnauld during the following year, but not until he had prepared the way for it by a number of earlier essays. He afterwards published several expositions of the theory especially in the Système nouveau (1695) and in the Monadologie (1714).—Leibnitz approaches his system first by the method of analysis, and then by the method of analogy. He seeks the ultimate presuppositions of science and then explains these presuppositions by means of analogy. Here he made a very important discovery, in showing that analogy is the only method by which to construct a positive metaphysics. Every mythology, religion and metaphysical system had used this method; but Leibnitz is the first to understand the principle which forms its basis. His system, the first attempt at a metaphysical idealism (i.e. the theory that the fundamental principle of reality is spiritual) since Plato and the pattern of all later idealistic attempts, has, to say nothing of its content, a permanent interest just because of this clear consciousness of its source. However if we should ask him why he uses the principle of analogy with so much assurance, he would answer: Because its help offers the only possibility of comprehending reality and because reality—on the basis of the principle of sufficient reason—must be comprehensible.

c. It was Leibnitz’ intention that his doctrine of Monads should form the complete antithesis to Spinozism. Whilst Spinoza recognized only one Substance, Leibnitz postulated an infinite number, each of which forms a universe of its own, or, to invert the expression, constitutes a separate view of the universe. Each Monad develops by virtue of an inner necessity, just like Spinoza’s Substance. Leibnitz’ theory thus appears to be an absolute pluralism in contrast with an equally absolute monism. Leibnitz’ only explanation of the ultimate correspondence and harmony of the Monads however, without which they could not constitute a universe, involves the reference to their common origin in God. The Monads issue or radiate from God, in a manner similar to the way in which Substance, according to Spinoza, impelled by the instinct of self-preservation, produced the Modes. But at this point—the conception of unity and multiplicity—Leibnitz encounters a difficulty which is even greater than that of Spinoza, since even God—just as every reality—must likewise be a Monad together with the other Monads, whilst Spinoza’s Substance maintains vital relation with the Modes.

Leibnitz also approaches very close to Spinoza in his conception of the relation of mind and matter. He insists on the continuity of all material processes and can therefore neither accept any transition from matter to mind nor any influence of mind upon matter. Extension is only the external sensible form of psychical states: that which takes place in the soul finds its material expression in the body and vice versa. Leibnitz therefore defends the hypothesis of identity just as Spinoza had done. He however gives it an idealistic cast, since he regarded the absolute reality as psychical, and denied the Spinozistic coordination of the two attributes.

d. A perfect continuity pervades the separate Monads, i.e. the individual life of the soul, just as the Monads among themselves form a complete continuous series. Every conceivable degree of soul-life exists, unconscious as well as conscious. Leibnitz developed his views on psychology and the theory of knowledge, as a polemic directed against Locke, in his Nouveaux Essais (which only appeared long after his death). He criticizes the assertion that the soul is originally a blank tablet. The obscure impulses of the soul must not be ignored. Just in proportion as the distinction and contrast between our sensations are small, the less a single element is distinguishable from the remaining content of the soul, or, more briefly, the more obscure the psychical states are, so much the more readily is their existence denied. But there are no absolute divisions, but rather every possible degree of variation between obscurity and clearness. Leibnitz calls the obscure changes within ourselves, which do not really rise to consciousness, perceptions; they correspond to the phantasmata of Hobbes. The lowest forms of being, the Monads of the lowest degree, never rise above such perceptions. We approach a higher level when perceptions are combined with memory and consequently possess more than mere momentary significance; consciousness is then present (sentiment, cf. Hobbes’ sensio). The highest degree is characterized by attention to its own states; here Leibnitz uses the terms apperception and conscience; conscience is connaissance reflexive de l’etat interieur, i.e. self-consciousness, not consciousness in general. The fact that the Cartesians attributed psychical life to human beings alone was due, according to Leibnitz, to their failure to observe the innumerable gradations of psychical life. Here, even as in material nature, the clear and sensibly apparent is a resultant, an integration of small magnitudes. The apparent evanescence of psychical life is merely a transmutation into more obscure, more elementary forms. The minute distinctions escape observation, and yet we are never wholly indifferent to them (just as in material nature there is no such thing as absolute rest). It is only when the distinctions become great and sharp that we are clearly aware of ourselves and feel the contrast between the self and the rest of the universe.

Leibnitz applies the principle of continuity consistently throughout, both in psychology and in the philosophy of nature, on the basis of the concept of minute differentia. As a mathematician the same thought process led him to the discovery of the integral calculus. His “differentials” are infinitely small magnitudes (or changes of magnitude), but they eventually constitute a finite magnitude through summation (integration). His great mind was occupied with problems in widely different fields of knowledge, but the general type of his thought was everywhere the same.

In referring all the distinctions of mental life to distinctions of obscurity and clearness, he is a forerunner of the century of enlightenment. But we must not overlook the fact that the obscure states have an infinite content, for each Monad is a mirror of the whole universe, even though it is conscious of only a part of it. A finite being is therefore incapable of complete and perfect enlightenment; its sole prospect consists of continuous effort. Leibnitz likewise discovers a tendency (appetite-tendance) in the soul, to pass from the single “perceptions” to new perceptions. This is an element which presupposes other distinctions than obscurity and clearness. Both Spinoza and Leibnitz contain suggestions of a profounder theory of will, which is suppressed by their intellectualistic tendency.

e. Although Leibnitz, in opposition to Locke, maintains the involuntary and unconscious foundation of knowledge, and objected to the idea of a tabula rasa, he is still in agreement with Locke’s criticism of “innate ideas” in requiring a proof for all truths, even the “innate,” that are not identical propositions. To prove a proposition means to trace it back to an identical proposition. According to him logic culminates in the principle of identity whilst the Aristotelians and Scholastics base their theory on the principle of contradiction. He had sketched an outline of logic in which each judgment is stated in the form of an identical proposition. But this sketch was unknown until 1840 (in J. E. Erdmann’s Opera philosophica Leibnitii), and the logical investigations of Boole and Jevons, which reveal a similar tendency, were the first to direct attention to them.

Just as the principle of identity is the criterion of truth in the realm of pure thought, so is the principle of sufficient reason in the realm of experience. Leibnitz however, even as Spinoza, never made a clear distinction between ground and cause (ratio and causa). He regarded this principle not only as a principle of scientific investigation, but as a universal law.—The difference between truths of experience (“contingent” truths) and truths of pure thought (“necessary” truths) is only a matter of degree: the former can be reduced to identical propositions by a finite, the latter by an infinite analysis. The relation is similar to that which obtains between rational and irrational numbers.

f. The whole of the Leibnizian philosophy is characterized by a harmonizing and conciliatory tendency. He is especially anxious to combine mechanism with teleology, but without compromising the integrity of either. Teleology is simply to be another way of construing mechanism. He says that “everything in nature can be explained by final causes (causæ finales) quite as well as by efficient causes (causæ efficientes).”

But he is not satisfied to stop with this purely philosophical theory, notwithstanding the fact that its empirical verification contained an abundance of problems. He was also anxious to effect a reconciliation between ecclesiastical theology and philosophy. He wrote the Theodicée in refutation of Bayle, just as he had written the Nouveaux Essais in refutation of Locke. Here he employs the distinction between “necessary” and “contingent” truths: nothing can contradict the former; but since “contingent” truths can never be reduced to a final analysis, such as the principle of sufficient reason requires, we are compelled to go beyond the series of actual causes (extra seriem) and postulate a first cause, which is self-caused. The universe, actually created by this first cause, was not the only one possible;—according to the principle of sufficient reason—it must have been given the preference only because it was the best possible. Before the creation of the world the various possibilities presented a conflict in the Divine mind. This world was given the preference because it offered the greatest harmony together with the greatest multiplicity. But even such a world cannot be entirely free from fault. It is impossible for the Divine Nature to reveal itself in finite nature without encountering numerous obstacles and limitations. Suffering (“physical evil”) and sin (“moral evil”) are consequences of these obstacles (“metaphysical evil”).—This reminds us of the mythology of Jacob Böhme. Leibnitz must concede to Bayle that the world is governed by two principles, with this modification, namely, that he ascribes the one to the divine will, which reduces evil to a minimum, the other to the divine understanding, which determines the various possible world forms.

But these are not the only arguments which Leibnitz adduces. He cites the infinitude of the universe, as admitting the possibility that the evil which we experience in our part of the universe (which is perhaps the worst part!) may be insignificant as compared with the world as a whole. This argument is new. It had only become possible through the new world-theory of Copernicus and Bruno. On the other hand, Leibnitz employs an old argument when he says that evil and sin were necessary in order that the good and the beautiful might be rendered conspicuous by contrast. This view occurs already in Plotinus and Augustine. It is rather aesthetic than moral. And moreover the sacrifice of single parts of the universe, i.e. single Monads, for the good of others, conflicts with Leibnitz’ own theory.

Leibnitz bases his ethical ideas on the longing for perfection, i.e. for a higher degree of energy and greater spiritual harmony. The sense of pleasure is correlated with an abundance and harmony of energies. The individual is spontaneously impelled to strive not only for his own happiness, but likewise for the happiness of others. In the controversy between Bossuet and Fenelon on the question of “disinterested love,” Leibnitz agrees with Fenelon, affirming the reality and the value of such love; he however emphasizes the fact that the happiness of others likewise affects us by way of reaction. He regards justice, conceived as the harmony of love and wisdom (caritas sapientis), as the highest virtue. Love is the end, and wisdom discovers the means.—Leibnitz’ theory, which he elaborated in two small dissertations, Von der Glückseligkeit and De nutionibus juris et justitiæ, is closely related to that of Shaftesbury, with which we shall become acquainted in the next division. Even Leibnitz himself referred to their similarity.