Chapter XXXIV (1)

_Outline of European Philosophy in the Seventeenth Century,
and the early part of the Eighteenth._

HAVING in the second volume of this work referred to the state of philosophy in relation to the Reformation, and the influence of that revolution in stimulating inquiry, an outline of the philosophic thought of Europe in the seventeenth century and the early part of the eighteenth will be an appropriate introduction to the subsequent history of Scottish philosophy. This will enable us to estimate the position and the claims of Scottish philosophy. Although the stream of European thought seems to run in several channels, these meet and influence each other at many points, and thus it is impossible to attain a just appreciation of the philosophy of one school or nation, without some general knowledge of the preceding and contemporaneous schools. So far as we know, there is nothing in the universe completely isolated, as all systems of philosophy are more or less related to each other, an entirely original idea is a rare phenomenon. But the field thus opened is exceedingly wide, and cannot be covered within the limits at my disposal. Therefore, it is to be distinctly understood that the aim of this outline is only to indicate the historical antecedents of the philosophy which subsequently arose in Scotland,――a matter of such interest and importance as to justify the attempt to elucidate its historic significance and relation to preceding systems of thought.

After the series of struggles which issued in the Reformation, the human mind continued to strive after independence and freedom for more than a century. Most of the philosophers of the sixteenth century were scholars and men of research, rather than unfettered thinkers, and exerted themselves in collecting old manuscripts, translating, annotating, and lecturing on the writings of Aristotle and Plato, while some of them manifested a tendency to theosophy, and others to materialism and scepticism. The veneration for the opinions of antiquity and the shackles of authority were not easily broken, and many curious moves were made ere reason and common-sense attained sway. At length men began to enter more and more on independent investigation of nature and mind, and the problem of moral freedom.

When undeterred by fear, interest, or authority, the human mind is the most powerful and wonderful agent in the universe. This was anew exemplified in the rapid development of mathematical science, and the adoption of more accurate methods of investigation in the seventeenth century, and ever since the progress of discovery and of invention have been continuous. It is my task to indicate briefly some of the intense wrestlings of those strong and exalted minds who have contributed to weaken the power of traditional authority, to brave the force of ignorance, of biting scorn, and of death itself.

Giordano Bruno was one of the boldest thinkers in the sixteenth century. Born at Nola――in the province of Naples――in 1548, he entered the Order of the Dominicans, but relinquished it when he found his convictions in conflict with the doctrines of the Church. From that time onward he lived a wandering life, sometimes sojourning in France, in England, in Germany, and sometimes in other countries. But having returned to Venice, he fell into the hands of the Inquisition in 1592, and after suffering a long imprisonment in Rome, was tried for heresy, condemned, and burned in 1600.

He was a voluminous author, and wrote both in Italian and in Latin, but several of his treatises and tracts have been lost. He was gifted with a lively, warm, and exuberant imagination, which often impelled him to express his views in a poetical form, and thus sometimes he embodied his thoughts in a haze of clouds; at other times, however, he delivered his opinions with remarkable force and clearness. The elements of sympathy were excessively strong in him, and entered into his modes of thought and coloured all his philosophic efforts.

Bruno boldly essayed the reconstruction of the universe on the principle of the unity and universality of substance. In astronomy he embraced the Copernican view, and expounded it. According to him, the universe is infinite in time and in space, the solar system being merely one of innumerable worlds, of which God is the original and immanent cause. The attributes of God are power, wisdom, and love. The stars are not moved by a prime mover, but by the souls inherent in them. He rejected the idea of a dualism of matter and form, and identified the form or moving cause with the end and matter of all organic things; thus matter contains in herself the forms of all things, and brings them forth from her own bosom as the travailing mother expels her offspring. The elements of all that exists are the monads, which are a kind of points, not entirely unextended but spherical, and at once material and psychical. The soul is a monad, and it is never wholly without a body. God is the monad of monads, and He is the least, as all things are external to Him, and the greatest, because all things are in Him. God caused the worlds to spring out of Himself, not by an act of mere will, but by an inner necessity, moving freely and without any compulsion. The worlds being nature realised, and God nature working, thus God is present in all things. Each of the worlds is perfect in its kind, and there is no positive evil. All individual objects and living organisms are subject to change, but the universe remains in its entire perfection always like itself.

Bruno’s philosophy is full of the unity of being, which is the principle and end of all philosophy. God is the infinite All, the One, the prime and universal substance, of Himself, excluding all delimitation, and is not to be sought beyond the universe and the infinity of things. “Why think of any twofold substance, one corporal and another spiritual, when in sum these have but one essence and one root, for corporal substance, which manifests to us that which it involves, must be held a thing divine, parent of natural things; and if you think aright, you will find a divine essence in all things.” Yet he occasionally speaks of the supernatural. “The highest contemplation which transcends nature is impossible and null to him who is without belief, for we attain to this by supernatural, not by natural light; and such light they have not who hold all things to be corporal, and who do not seek Deity beyond the infinite world and the infinity of things, but within this and these.”¹

¹ The works in which Bruno chiefly developed his system were
written in Italian, and of these the most important is
the “Della Causa, Principio et Uno,” 1584, and in the
same year appeared his “De l’Infinito Universo e Mondi.” A
complete list of his writings is given in the second volume
of Ueberweg’s _History of Philosophy_ (page 469). In the
present century the extant writings of Bruno have been
carefully studied and ably expounded by several eminent
writers and historians of philosophy.

It is obvious that Bruno’s philosophy is a form of pantheism, one of the most fascinating systems of thought ever propounded. The system originates from the difficulty of conceiving the action of the mind or thought except when conjoined with a body――an insuperable and far-reaching difficulty, because there is no direct evidence anywhere of a mind operating without the conjunction of an organism. Hence the strong temptation to identify God and the universe in one idea or principle: that is, the universe is God, and God is the universe. This is a proposition which imparts no light, but it is, nevertheless, the fundamental idea of the system which figures the external substance of the universe as God, from which step by step all things have issued. Thus the prime idea of pantheism is a constant quantity or unity, although the developments of the system in the hands of different thinkers has assumed varied modifications in detail.

Bruno’s views have influenced the subsequent developments of several once famous philosophies. The noted Spinoza was indebted to him for several of his ideas, but the fundamental idea of pantheism is much older than the times of either of the two philosophers, as it stretches back to an early period in the evolution of human thought. Through Spinoza’s system German speculation has been largely influenced, and even some recent Scottish speculations bear distinct traces of a similar descent.

In France, during the latter part of the sixteenth century, the Jesuits were the most active instructors and disseminators of doctrine. Their schools were planted in all the chief towns of the nations. They encouraged the study of classical literature, and prepared the best text-books and lexicons. But they were a conservative and obstructive body, and wielded much influence over the intellect of the French. At the same time a form of ancient scepticism was revived in France by Montaigne. “In fact, Montaigne represents, if he did not inaugurate, the school of French satirists, who, standing between, as it were, Calvin and Rabelais, avoided both the coarseness and abandon of the latter, and the ascetic sternness and awkward pleasantries of the former.”¹ His sceptical views were more or less directed to the doctrines of Christianity, but from whatever motive or reason, he generally concluded with a recognition of the necessity of a revelation, and thus avoided a conflict with theology. In their ultimate result his reflections pointed to such conclusions as――whether we are not a rather presumptuous class of beings in fancying that we have any higher faculties than those which are bestowed on other animals; whether the pursuit of truth may not be a pleasant amusement, rather than one that promises any result; whether religious forms may not be serviceable to the business of life, and therefore to be defended; whether they do not become mischievous when they lead to conflicts and to persecutions; whether a full recognition of our folly, ignorance, and uncertainty, might not save us from the dogmatism which produces such things? A similar strain of thought was indulged in by Charron and other French writers.²

¹ Van Laun’s _History of French Literature_, Volume II., pages
299‒300.

² Montaigne’s _Essays_. He states himself that Buchanan was
one of his preceptors; and some traces of this Scotsman’s
opinions may be found in the easy and self-satisfied
Frenchman’s writings.

Another Frenchman, Gassendi, undertook the defence of Epicureanism, showing that it contained the best doctrine of physics, and also attempting to combine it with Christian theology. In physics, he embraced the theory of atomism; but he saw its weak side, namely, the difficulty of explaining the derivation of sensation out of atoms and space. He discussed this problem at great length, but admitted that there was something left unexplained. He was a voluminous writer.

Gassendi has been claimed by the historians of materialism as the chief reviver of systematic materialism in modern times. “We lay especial stress upon this, that Gassendi drew again into the light, adapted to the circumstances of the time, the fullest of the materialistic systems of antiquity, that of Epikuros.” Again, in reference to his historical qualifications, “Gassendi, whose thorough philological and historical training equipped him with a knowledge of all the systems of antiquity, embraced with a sure glance exactly what was best suited to modern times, and to the empirical tendency of his age. Atomism, by his means drawn again from antiquity, attained a lasting importance, however much it was gradually modified as it passed through the hands of later inquirers.” Once more, “Gassendi is, of all the most prominent representatives of materialism, the only one gifted with a historic sense, and that he has in an eminent degree. Even in his ‘Syntagma Philosophicum,’ he treats every subject at first historically, from all possible points of view.”¹

¹ Lange’s _History of Materialism_, Volume I., pages 253‒269.
“The evolution and dissolution of things is nothing but the
union and separation of atoms. When a piece of wood is burned,
the flame, smell, and ashes, and so on, have already existed
in their atoms, only in other conditions. All change is only
movement in the constituents of a thing, and hence the simple
substance cannot change, but only continues its movements in
space.”――_Ibid._, page 267.

Descartes was born in 1596 at La Haye, in the province of Touraine. At the age of eight he was sent to the Jesuit College of La Flèche, and placed under the instruction of the Jesuits, where he remained for eight years, and received his general education. He was a contemporary of Gassendi, and a more famous philosopher; each represented opposite systems and assailed one another, but neither of them influenced the other in his views. The two were contrasted in every way. Descartes always aimed at being original, and often was so, while Gassendi was more historical and dependent, and more learned, but he lacked the genius of his contemporary; both, however, were the fathers of great modern schools of thought. In philosophy and in scientific method, the real turning-point came in the early part of the seventeenth century, and in the great movement Descartes holds a foremost place, entitling him to some account, however brief, in this exposition.

Descartes was eminent both as a philosopher and as a mathematician; in the latter department of science he takes a position among the great mathematicians of the seventeenth century. In algebra he was the first to place the doctrine of powers on a clear basis, freeing it from its dependence on geometry, which prevented its proper expansion; while, by introducing the index notation, he gave the science a new and potent means of expression. He also advanced the treatment of negative quantities, and first brought into prominence the equal significance of the negative roots, and for determining a limit to their number, gave the rule which still bears his name. But his fame as a mathematician rests chiefly on his application of algebra for “the expression of continuously varying quantity.” By this invention he may be considered as the founder of analytic geometry, or the algebraic treatment of curves, and he is well entitled to a place in the history of the mathematical achievements which ultimately led to the discovery of the Differential Calculus.¹

¹ _Descartes_, by J. P. Mahaffy, pages 207‒209, 1880. It was
a curious feature in the character of Descartes that he
designedly so composed his Essay on Geometry as to be very
difficult, “and only understood by mathematicians of a high
order. He omitted what was obvious, and in the solving of
problems only gave the means of solution, and not each step
in the demonstrations. He even chuckles in his letters at the
number of professed mathematicians who were unable to follow
his arguments, and tells us that not a single professor in
the new universities of Holland was able to open his mouth
upon the subject.”

In physics, his achievements were mainly in the science of optics. He at least contributed to the discovery and statement of the law of refraction, though his independent discovery of this law has been keenly disputed. He explained the colours of the rainbow, and it appears that he originated the undulatory theory of light. But his positive contributions to science were not the most important elements of his philosophy, as its influence sprang more from its spirit and method, which were the expression of his own acute and determined mind.

Descartes’ philosophy is fundamentally a deductive system, based on mathematical principles, but in its development it assumed the form of a methodical and rather dogmatic rationalism. Although the initial steps of his method are founded in doubt, this is not the most distinctive feature of his philosophy. His doubt, at the threshold, merely gave him the data of his own thought and existence, and enabled him to assert a right to discard authority, and to erect a standard independent of all former times and thinkers. In the development of his system he attempted to find the ultimate principle in the order of synthesis, which would afford the conditions of philosophy and of science, or that something which is the highest of all. This principle must be self-evident, and Descartes found it in his famous “cogito ergo sum;” then he struggled hard and determinedly to connect this with the idea of God, and thus associating the criterion of truth with the perception of Deity, makes the one in a sense dependent on the other. In his first published work, which appeared in 1637, and marks an epoch in the history of human thought, he enunciated four rules of method in the following order:――“1. Never to accept anything as true which was not clearly known to be such; that is, carefully to avoid precipitancy and prejudice, and to include nothing more in my judgment than what was presented to my mind so clearly and distinctly as to exclude all ground of doubt. 2. To divide each of the difficulties into as many parts as possible, and as might be necessary for its adequate solution. 3. To conduct my thoughts in order, by commencing with objects, the simplest and easiest kind to know, that I might ascend by degrees, as it were, step by step, to the knowledge of the more complex; assigning in thought a definite order even to objects which in their own nature do not stand in a relation of antecedence and sequence. 4. In every case to make enumerations so complete, and reviews so general, that I might be assured that nothing was omitted.”¹ This work was entitled, “Discourse on the Method of Rightly Conducting the Reason and Seeking Truth in the Sciences; also the Dioptrics, the Meteors, and the Geometry, which are Essays in this Method.” Thus Descartes introduced his Method to the world with the recommendation of his own discoveries in mathematics, and with the solution of problems which were then beyond the reach of ordinary minds, as was indicated in the last note. The three essays presented as applications of his Method have long been superseded or absorbed in later works, but the discourse on Method will always be valuable. The volume containing the whole was written in French, which in that day was itself a bold innovation.

¹ _Discourse on Method_, Part II.

The Discourse on Method though only a short treatise, which might be read at a single sitting, nevertheless was a memorable proclamation against the ages of inert formalism, and the thraldom of the human mind. It contains details relating to the formation of his opinions, and the beginning of the development of his system. It is a book of absorbing interest, and should be carefully read by every student of philosophy. It is divided into six parts, which treat of the following topics: ――1. Various considerations touching the Sciences. 2. The principal rules of the author’s method, the heads of which I have stated above. 3. Some rules of morals deduced from this method. 4. His reasonings establishing the existence of God and of the human soul. 5. The order of the questions in physics, the explanation of the motion of the heart and of some other difficulties, as also the difference between the soul of man and that of the brutes. 6. What he believes to be requisite in order to greater advancement in the investigation of nature than has yet been made, with the reasons that have induced him to write. I had transcribed several passages for quotation, but space forbids their insertion; and as the work is now easily accessible to English readers, long quotations are unnecessary. But to lighten the exposition, I may briefly dispose of some of his peculiar views touching the organisation of man and the lower animals.

He adopted a mechanical theory of the universe, attributing to matter only pressure and impulsion, by which to explain all material phenomena. Then developing his theory in accounting for life, plants, and animals, he ultimately arrived at the conclusion that the functions and actions of animals and living organisms are purely the result of heat and motion, as mechanically as the going of a clock is the result of cog-wheels and pulleys. Thus man so far as his body is concerned, is merely an automaton, while all the lower animals are automatons, mere machines, constructed by the Deity according to the general laws which He has impressed upon matter: they have no rational soul, as they use no language, or perform any actions which cannot be proved to be the direct result of their internal organism.

Touching the origin of the human soul, he followed the very old notion of supposing that God infused a soul into every human being at the first moment of its existence, and thus the soul was radically distinct from the body, though closely united with it. As an unextended entity, however, the soul can be in contact with the body only at one point, which is the brain, or more precisely, in the single centre of the mass, the conarium, or pineal gland. He says, “Although the human soul is united to the whole body, it has, nevertheless, its principal seat in the brain, where alone it not only understands and imagines, but also perceives, and this by the medium of the nerves, which are extended like threads from the brain to all the other members, with which they are so connected that we can hardly touch any one of them without moving the extremities of those nerves which are collected in the brain round the seat of the soul.” Again, “It is clearly established, however, that the soul does not perceive in so far as it is in each member of the body, but only so far as it is in the brain, when the nerves by their movements convey to it the diverse actions of external objects that touch the parts of the body in which they are inserted.”¹

¹ _Principles of Philosophy_, IV., 189, 196.

The Discourse on Method contained in a condensed form the principles and chief characteristics of Descartes’ system, and it was followed by his “Meditations,” which were published in 1641. As the subject was so full of difficulties, and thus liable to much misunderstanding and misconception, he had manuscript copies of his “Meditations,” submitted for criticism to some of the most learned men and philosophers of the time, among whom were Gassendi, Arnauld, Hobbes, and others. A summary of their objections, with his replies, was published, and many of their criticisms were able and just. But Descartes so firmly believed in his own system, and was so convinced that he saw it all clearly and distinctly, that he could hardly be moved to change any of his settled ideas. He simply wanted these learned men’s objections, that he might refute them, and thus more effectually establish the certainty of his own system in other minds. To the Catholic theologians only, for the sake of their patronage and peace, he conceded some trifling points.

The Meditations are an expansion of the metaphysics of his Discourse on Method, and the work embraced six meditations, which treat on the following subjects: “Of the Things of which we may Doubt; of the Nature of the Human Mind, and that it is more easily known than the body; of God, that He Exists; of Truth and Error; of the Essence of Material Things, and of God; of the Existence of Material Things, and of the real distinction between the mind and body of man.” In his preface to these Meditations he says: “Now that I have once, in some measure, made proof of the opinions of men regarding my work, I again undertake to treat of God and the human soul, and at the same time to discuss the principles of the entire First Philosophy, without, however, expecting any commendation from the crowd for my endeavours, or a wide circle of readers. On the contrary, I would advise none to read this work unless such as are able and willing to meditate with me in earnest, to detach their minds from commerce with the senses, and likewise to deliver themselves from prejudice; and individuals of this character are, as I well know, remarkably rare. But with regard to those who, without caring to comprehend the order and connection of the reasonings, shall study only detached clauses for the purpose of small but noisy criticism, as is the custom with many, I may say that such persons will not profit greatly by the reading of this treatise; and although, perhaps, they may find opportunity for cavilling in several places, they will yet hardly start any pressing objections, or such as shall be deserving of reply.”

Thus the Meditations were intended to be a discussion on the first or fundamental principles of philosophy, but their main drift is to prove that the knowledge of God and of the mind is the most certain of all things. This was attempted in two ways: first, by showing the uncertainty of all our knowledge of bodies, and then by presenting demonstrations of our own existence as thinking beings, and of the existence of the Deity. The first Meditation expounded the grounds on which we may doubt of all things, and especially of all material objects. After showing the uncertainty of all things, save some points in arithmetic and geometry, he affirmed his own strong belief in the existence of an all-powerful God, who created him such as he was, and then says: “If, however, it were repugnant to the goodness of God to have created me subject to constant deception, it would seem likewise to be contrary to his goodness to allow me to be occasionally deceived, and yet it is clear that this is permitted. Some, indeed, might perhaps be found who would be disposed rather to deny the existence of a Being so powerful than to believe that there is nothing certain. But let us for the present refrain from opposing this opinion, and grant that all which is here said of God is fabulous, nevertheless, in whatever way it may be supposed that I reached the state in which I exist, whether by fate, or chance, or by an endless series of antecedents and consequents, or by any other means, it is clear (since to be deceived and to err is a certain defect) that the probability of my being so imperfect as to be the constant victim of deception, will be increased exactly in proportion as the power possessed by the cause, to which they assign my origin, is lessened. To these reasonings I have assuredly nothing to reply, but am constrained at last to avow that there is nothing of all that I formerly believed to be true of which it is impossible to doubt.” Having now disposed so far of all material objects, in the second, he repeats his argument affirming from the fact of doubt, our own existence as doubting beings. “But what, then, am I? A thinking thing, it has been said. But what is a thinking thing? It is a thing that doubts, understands, affirms, denies, wills, refuses, that imagines also, and perceives. Assuredly it is not little, if all these properties belong to my nature. But why should they not belong to it? Am I not that very being who now doubts of almost everything, who, for all that, understands and conceives certain things, who affirms one alone as true, and denies the others, who desires to know more of them, and does not wish to be deceived”; and so on in the same line of argument. He next showed that external objects can only be known when they become or are made the objects of thought, and then makes a vigorous effort showing that mind itself is more clearly known than any or all the objects of the external world. “But, finally, what shall I say of the mind itself, that is, of myself? for as yet I do not admit that I am anything but mind. What, then? I who seem to possess so distinct an apprehension of the piece of wax,――do I not know myself, both with greater truth and certitude, and also much more distinctly and clearly? For if I judge that the wax exists because I see it, it assuredly follows, much more evidently, that I myself am or exist, for the same reason, it is possible that what I see may not in truth be wax, and that I do not even possess eyes with which to see anything; but it cannot be that when I see, or, which comes to the same thing, when I think I see, I myself who think am nothing. So, likewise, if I judge that the wax exists because I touch it, it will still also follow that I am, and if I determine that my imagination, or any other cause, whatever it be, persuades me of the existence of the wax, I will still draw the same conclusion. And what is here remarked of the piece of wax is applicable to all the other things that are external to me.”

In the third Meditation he unfolded his chief argument for the existence of God. He insisted that as the idea of God in the human mind is innate, God himself is its cause. And he described God thus:――“By the name of God, I understand a substance infinite, eternal, immutable, independent, all-knowing, all-powerful, and by which I myself, and every other thing that exists, if any such there be, were created.” Here he associates God, or the idea of God, with his own criterion of truth. In the fourth, he proceeded to show that all which we clearly and distinctly perceive must be true, and then explained the nature of intellectual error. Referring to the will as the cause of error, he says: “I have no reason to complain because God has given me a will more ample than my understanding, since, as the will consists only of a single element, and that indivisible, it would appear that this faculty is of such a nature that nothing could be taken from it without destroying it; and certainly, the more extensive it is, the more cause I have to thank the goodness of Him who bestowed it upon me.... For as often as I so restrain my will within the limits of my knowledge, that it forms no judgment except regarding objects which are clearly and distinctly represented to it by the understanding, I can never be deceived, because every clear and distinct conception is doubtless something, and as such cannot owe its origin to nothing, but must of necessity have God for its author――God, I say, who, as supremely perfect, cannot, without a contradiction, be the cause of any error, and consequently it is necessary to conclude that every such conception or judgment is true.”

He began the fifth Meditation by expounding the essence of material things, giving some examples from quantity and form. And he asserted that the figure of a triangle ♦and other mathematical figures possess a certain determinate form, or essence, which is immutable and eternal; and again repeated that whatever is clearly and distinctly perceived is true, truth being identical with existence. He then proceeded to demonstrate in a somewhat new form his arguments for proving the existence of God, and making all knowledge dependent upon this. “But I remark further that the certainty of all other truths is so absolutely dependent on it, that without this knowledge it is impossible ever to know anything perfectly.... And thus I very clearly see that the certainty and truth of all science depends on the knowledge alone of the true God, inasmuch that, before I knew him, I could have no perfect knowledge of any other thing. And now that I know him, I possess the means of acquiring a perfect knowledge regarding innumerable matters, as well relating to God himself and other intellectual objects as to corporeal nature.” In the sixth he explained the difference between imagination and pure intellection; reviewed the errors of the senses, pointing out the means of avoiding them, the distinct difference of the mind and the body, and their relation to each other, and then adduces the evidence from which the existence of the external world may be inferred, and all with the aim of showing that our knowledge of external objects is not so clear and distinct as the knowledge which we have of our own minds and of God. Thus far I have attempted to explain Descartes’ own efforts to develop his philosophy.

♦ “aud” replaced with “and”

But it is in his work entitled _The Principles of Philosophy_, written in Latin, and published in 1644, that he developed his theories and ideas systematically, and gave the most complete exposition and representation of his system.¹ In this work he expounded his philosophy synthetically. It is divided into four parts, which treat consecutively of the principles of human knowledge, of the principles of material things, of the visible world, and of the earth. The first part contains an orderly summary of his metaphysical views, repeating what had been stated in the Discourse and the Meditations, and adding some new elucidations. And it is chiefly to this part that I must direct attention, as being most consonant to the aim of this chapter.

¹ In a long preface to the French translation of his
_Principles of Philosophy_, which appeared in 1647, Descartes
enters at some length on several topics of an interesting
character, which are still well worth reading.

But not to leave his physics altogether unnoticed, the following is a brief indication of his physical theory. Basing his ideas on mathematics, he boldly asserted that extension is an eternal attribute of matter, and that to us it is the very essence of matter. “Give me extension and motion,” he exclaims, “and I will construct the universe.” Matter is infinite or unlimited in space or time, and it is everywhere identical with extension, all differences of quality being simply produced by a different mechanical composition, and a difference of motion in its parts.

In the second part of his Principles, he reduces all the phenomena of nature to variations of size, figure, and motion, in the minute particles of a homogeneous matter, there being but one kind of matter in the whole universe. He gave special laws of motion, which are now superseded. In the third part he treated on the theory of the solar system, and on the nature and origin of the fixed stars, and assuming three elements of various density in degree, explained the whole universe by the theory of vortices or of circular motion. In the fourth part he treated of the earth and its formation, of water, fire, and other matters.

“When he gives _a priori_ explanations of all manner of phenomena in heaven and in earth, deduced from the motion of diverse particles, he confesses that the plurality of causes which may produce the same effect is his great difficulty. He feels that endless time and outlay is required to verify his theories by crucial experiments, and till that has been done, he can offer nothing but the satisfactoriness and simplicity of the explanation as a guarantee of its truth. Once, indeed, he advances the statement that the veracity of the Deity would come into question if he permitted us to be deceived in following such strict and sober demonstrations. But in general the distinction of purely mathematical and physical proof is acknowledged by Descartes, and he confesses the possibility, though he never admits the fact, that he might be mistaken.”¹

¹ _Descartes_, by J. W. Mahaffy, page 163.

The most notable peculiarities of Descartes’ metaphysics are his conception of God and his definition of Substance. He says that in the concept of God is comprised absolutely necessary and external existence, while our concept of other things merely includes contingent existence. God is also omniscient, all-powerful, absolutely perfect, absolutely veracious, and the source of all light, “so that it is plainly repugnant for him to deceive us.”¹ He exerted his great powers to make this clear, and if his premisses were true, the conclusions of course would follow, but his assumption of an innate idea of God in the human mind of such a character as he assigned to it, is nowhere to be found save among a small section of the most cultivated of the race. Besides it is very questionable if this idea of God be obtained at all in the way which he maintained. Then he defined substance thus: “By substance we can conceive nothing else than a thing which exists in such a way as to stand in need of nothing beyond itself in order to its existence. And, in truth, there can be conceived but one substance which is absolutely independent, and that is God.” We perceive that all other things can exist only by the concourse of God; and, accordingly, the term substance does not apply to God and the creatures in the same sense, and no meaning of this word can be distinctly understood which is common to God and them. Created substances, however, of all kinds may be conceived as things existing by the concourse of God, but existence by itself is not observed by us. Every substance has one principal attribute, as thinking of the mind, extension of the body. Thus extension in length, breadth, and depth constitutes the nature of corporeal substance, and thought the nature of thinking substance. For everything else that can be attributed to body presupposes extension, and is only some mode of an extended thing, just as all the properties which we discover in the mind are only different modes of thinking.²

¹ _Principles of Philosophy_, I. 22, 23, 29.

² _Principles of Philosophy_, I., 51, 52, 53.

His doctrine of the concourse of God is thus explained: “Because I was in existence a short time ago, it does not follow that I must now exist, unless in this moment some cause create me anew as it were, that is, conserve me. In truth, it is perfectly clear and evident to all who attentively consider the nature of duration, that the conservation of a substance, in each moment of its duration, requires the same power and act that would be necessary to create it, supposing it were not yet in existence; so that it is manifestly a dictate of the natural light that conservation and creation differ merely in respect of our mode of thinking and not in reality.” Again, “From the fact that we now are, it does not necessarily follow that we shall be a moment afterwards, unless some cause, namely, that which first created us, shall, as it were, continually recreate us, that is, conserve us. For we easily understand that there is no power in us by which we can conserve ourselves, and that the being who has so much power as to conserve us out of himself, must also by so much the greater reason conserve himself, or rather stand in need of being conserved by no one whatever, and, in fine, be God.”¹

¹ _Meditation_, III.; _Principles of Philosophy_, I., 21.

It is pretty evident that the above view of substance contained an element of pantheism. Since that substance which exists entirely in itself and absolutely independent of aught beyond itself, is declared to be God; and since there is only one kind of matter in the universe, the sum and essence of substance being included in extension, what is God but the universe. Hence Spinoza adopted this Cartesian conception, and placed it at the summit of his pantheistic system of the universe; while Descartes’ doctrine of conservation or continuous creation seems to have suggested to his distinguished follower Geulinx the doctrine of Occasional Causes; and Malebranche also made a modification on the former doctrine in his own theory of seeing all things in God, who is the place of spirits.¹ In truth, Descartes’ theory of the relation of body and mind, even when supported by divine conservation, was unsatisfactory and scarcely conceivable.

¹ Geulinx’s _Commentaries on Descartes’ Principles of
Philosophy_; Malebranche’s _De la Recherche_, etc.

Touching his first principle, and the criterion of truth, which are involved in each other, he said:――“I think, therefore, I am, and this proposition is of all others the first and most certain which occurs to one philosophising orderly.” Thus knowledge must begin with a definite act of a conscious being, self-revealed in the conscious act. He did not, indeed, analyse the conditions of the object of which the self-conscious being takes notice, or trace how the conscious act has originated. Nevertheless, it was an important step towards placing investigation on the true basis of conscious experience; though, of course, on the subjective and notional side, it has often been carried to extremes, and was so in the end by Descartes himself. He endeavoured to deduce a criterion of truth from his first certain proposition, and this he founded on clearness and distinctness of knowledge. This test he defined in these words:――“I call that clear which is present and manifest to the mind giving attention to it, just as we are said clearly to see objects when, being present to the eye looking on, they stimulate it with sufficient force, and it is disposed to regard them; but the distinct is that which is so precise and different from all other objects as to comprehend in itself only what is clear.” As already stated, he called in the veracity of God to support this criterion of truth.¹ But it is vague and comparatively useless in its application, since it must be admitted that the clearness and distinctness of an idea, a conviction, or an opinion, in the mind of the person holding them, is not always a guarantee of their truth; although it is a very good reason for such opinions and ideas being strongly asserted and firmly maintained.

¹ _Principles of Philosophy_, I., 45, IV., 206; _Meditations_,
IV.

Descartes’ metaphysics does not reach the external world by a distinct perception, but by an indirect or mediate inference. First, he resolved to prove his own existence as a thinking being, and then deduced the existence of God from the fact that thinking beings exist who possess the idea of him, before the external world came into view at all. He presented his demonstration of God’s existence under three forms, which, however, are all essentially founded on the idea that he himself had of God; and they are neither wholly new nor at all satisfactory, and raised a storm of controversy which raged long and widely.

Turning to Descartes’ psychology, which is not separately or exhaustively treated in his writings, and on some points there is a little difficulty in ascertaining his views. He called the mind a thinking substance or thinking thing; the word thought meant all that we are immediately conscious of; and, accordingly, not only to understand, to will, to imagine, but even to perceive, have here the same meaning as thinking. There are only two modes of thinking of which we are conscious, namely, the perception or operation of the understanding, and volition or the operation of the will; thus to perceive through the senses, to imagine, and to conceive purely mental objects, are only different modes of perceiving; but to desire, to be averse from, to affirm, to deny, to doubt, are different modes of willing.¹

¹ _Principles of Philosophy_, I., 9, 32. He says that the
simplest self-evident notions are only obscured by logical
definitions, as these are not to be reckoned among the
cognitions acquired by study, but as born with us. _Ibid._,
10.

The word perception has a wider meaning in the writings of Descartes and his followers than in the philosophic literature of the present time. With them perception was generally employed to indicate an act of mind by which we apprehended any mental object, as distinguished from an affirmation or judgment concerning it; and thus in their writings perception is nearly equivalent to cognition. All acts of memory, of imagination, of sense, and of pure intellect, are merely modes of perceiving, as in each we only know as being conscious of the object of the act.

But here we come face to face with the relation of the mind to the objects of its knowledge, which is the crucial problem in philosophy and in psychology. As already implicitly stated above, according to Descartes, the mind has no immediate perception of external objects or of the material world. On the principles of his theory, the mind can have no immediate knowledge of anything beyond its own modifications. Although the mind is only conscious of its own modifications or ideas, still it is not solely modified by its own energy, and in many instances it is affected by the antecedent affections of the body, owing to its junction therewith. Thus some of the modifications of the mind are affections originating from the body, and mainly relative to it; others, though not quite independent of corporeal contact, must be more especially considered as affections of the mind; while others are in themselves purely or absolutely intellectual energies in their origin and in their continuance. The point of alliance of the mind with the body is the brain, at this point all organic changes from external causes terminate, and through these the mind is, owing to the nature of its junction, hyperphysically determined to a relative modification. There also all corporeal movements, at the call of the will, commence, and thus produce the bodily movement answering to the volition of the mind. The mind only perceives objects as its seat in the brain, and not at the point of affection in the organs.¹

¹ _Principles of Philosophy_, I., 48, 53; III., 2, 3; IV., 189,
196‒198. Hamilton’s _Reid_, note N.

Thus we have only a mediate perception of an external object: a representation of the object is all that is known to us, as it is that only which comes within the seat of the conscious mind. This mental representation of the external object is called an idea.¹ The organic movement at the point of junction in the brain may also metaphorically be called an impression, as it is the result of an external impulse, though at the same time it has no natural resemblance to the external object; it may be termed an image, as in some way suggesting the representation to the mind; or it may be named a corporeal species, though nothing similar to itself is transmitted from the object; or it may be styled an idea, though it is not the immediate object of the mind. If any one say that this theory of mediate perception retains no evidence of the reality of an external world consistent with the representations of our own minds, Descartes replies, that in consequence of our early and deep-rooted prejudices we are led to attribute to the immediate objects of our perceptions an external and chief, instead of internal and vicarious, existence. “Hence arose the belief that there was more substance or body in rocks and metals than in water or air, because the mind perceived in them more hardness and weight. Moreover, the air was thought to be merely nothing so long as we experienced no agitation of it by the wind, or did not feel it hot or cold. And because the stars gave hardly more light than the slender flames of candles, we supposed that each star was but of this size. Again, since the mind did not perceive that the earth moved on its axis, or that its superficies was curved like that of a globe, it was on that account more ready to judge the earth immovable and its surface flat.” Of course, he also appeals to the veracity of the ♦Deity.²

¹ But whether his idea is to be considered as having an
existence independent of the mind or not, was a disputed
point among Descartes’ followers.

♦ “Diety” replaced with “Deity”

² _Principles of Philosophy_, I., 66‒72.

Descartes used the term idea to denote both mental objects and mental acts, applying it indifferently to a material or a mental modification, in relation to sense and imagination. Hence throughout his writings this term appears under many relations and many different meanings. It is often employed as an object of consciousness, as a representative thought; while sometimes an objective and sometimes a subjective meaning is attached to it, and this in all degrees and relations of mind itself and its objects.

Touching his doctrine of innate ideas, which is a necessary part of his theory of body and mind, the hyperphysical element of his system, which he seems to have deemed requisite to cover and assist the purely mathematical and mechanical principles upon which his philosophy is essentially founded. By innate ideas he meant mental modifications existing in the mind prior to all experience, and that they come into consciousness whenever the mind begins to think and reflect. To the class of innate modifications belong the ideas of God, of substance, of unity, and others. These ideas might remain long inactive in the mind, but they always exist in it potentially. And it is in relation to these ideas that the veracity of the Deity is all-important, because a malign Creator could have made us believe innate falsehoods.¹

¹ “With respect to ideas, some of them appear to me to be
innate.” _Meditations_ III. “The mind first of all discovers
within itself the ideas of many things ... the mind also
discovers certain common notions out of which it frames
various demonstrations that carry conviction to such a degree
as to render doubt of their truth impossible, so long as
we give attention to them. For example, the mind has within
itself ideas of numbers and figures; and it has also among
its common notions the principle that if equals be added to
equals the whole will be equal, and the like.”――_Principles
of Philosophy_, I., 13.

“In the first place, I discover that it is impossible for
God ever to deceive me, for in all fraud and deceit there is
some imperfection: and although it may seem that the ability
to deceive is a mark of subtlety or power, yet the will
testifies without doubt of malice and weakness; and such,
accordingly, cannot be found in God. In the next place, I
am conscious that I possess a certain faculty of judging
or discerning truth from error, which I doubtless received
from God, along with whatever else is mine; and since it is
impossible that he should will to deceive me, it is likewise
certain that he has not given me a faculty that will ever
lead me into error, provided I use it aright.”――_Meditations_
IV.

His exposition of the senses, or sensation, is comparatively brief, but interesting and important.

In his treatise on the passions, he admitted six primitive passions or emotions, namely, admiration, love, hate, desire, joy, and sadness. From these he sought to deduce all the other passions and emotions, but his exposition is mainly an echo of the views of Aristotle. He, however, stated that the most perfect of all emotions is intellectual love to God.

Touching ethics, Descartes expressly declined to produce a formal work, on the ground that it would be liable to violent and unfair criticism from his opponents; for a similar reason he refrained entirely from treating of religion or of faith, preferring, as he says, to adhere to the faith, and to submit to the authority of the Roman Catholic Church, in which he had been educated from childhood. Yet occasionally in his writings he touches on moral subjects, and in his letters on the sovereign good, in his criticism of Seneca, and in his treatise on the passions, he has indicated his ethical views. But he contributed nothing specially original in this department, as he approached the subject from the ancient standpoint, not from the modern, and he does not treat the question of the moral faculty, or moral obligation. Still his views, so far as they go, are generally wise and just.

But, as already indicated, the influence of Descartes did not quite depend on the positive results of his philosophy. The emphatic doubt at the threshold of his system was, in my opinion, the most influential element in his philosophy. He had many disciples and many opponents, while theologians generally were his bitterest enemies. Nevertheless, Cartesianism spread in France and held its ground till about the middle of the eighteenth century; while the influence of his system was felt in other countries of Europe, especially in Holland. As for the general tendency of his system in subsequent speculation and in literature, it appeared in idealism, rationalism, and especially in scepticism and nihilism.