The estimate of the value of the history of philosophy in general, given at the start, is the more true of the history of modern philosophy, since the movement introduced by the latter still goes on unfinished. We are still at work on the problems which were brought forward by Descartes, Locke, and Leibnitz, and which Kant gathered up into the critical or transcendental question. The present continues to be governed by the ideal of culture which Bacon proposed and Fichte exalted to a higher level; we all live under the unweakened spell of that view of the world which was developed in hostile opposition to Scholasticism, and through the enduring influence of those mighty geographical and scientific discoveries and religious reforms which marked the entrance of the modern period. It is true, indeed, that the transition brought about by Kant's noëtical and ethical revolution was of great significance,—more significant even than the Socratic period, with which we are fond of comparing it; much that was new was woven on, much of the old, weakened, broken, destroyed. And yet, if we take into account the historical after-influence of Cartesianism, we shall find that the thread was only knotted and twisted by Kantianism, not cut through. The continued power of the pre-Kantian modes of thought is shown by the fact that Spinoza has been revived in Fichte and Schelling, Leibnitz in Herbart and Hegel, the sensationalism of the French Illuminati in Feuerbach; and that even materialism, which had been struck down by the criticism of the reason (one would have thought forever), has again raised its head. Even that most narrow tendency of the early philosophy of the modern period, the apotheosis of cognition is,—in spite of the moralistic counter-movement of Kant and Fichte,—the controlling motive in the last of the great idealistic systems, while it also continues to exercise a marvelously powerful influence on the convictions of our Hegel-weary age, alike within the sphere of philosophy and (still more) without it. In view of the intimate relations between contemporary inquiry and the progress of thought since the beginning of the modern period, acquaintance with the latter, which it is the aim of this History to facilitate, becomes a pressing duty. To study the history of philosophy since Descartes is to study the pre-conditions of contemporary philosophy.
We begin with an outline sketch of the general characteristics of modern philosophy. These may be most conveniently described by comparing them with the characteristics of ancient and of mediaeval philosophy. The character of ancient philosophy or Greek philosophy,—for they are practically the same,—is predominantly aesthetic. The Greek holds beauty and truth closely akin and inseparable; "cosmos" is his common expression for the world and for ornament. The universe is for him a harmony, an organism, a work of art, before which he stands in admiration and reverential awe. In quiet contemplation, as with the eye of a connoisseur, he looks upon the world or the individual object as a well-ordered whole, more disposed to enjoy the congruity of its parts than to study out its ultimate elements. He prefers contemplation to analysis, his thought is plastic, not anatomical. He finds the nature of the object in its form; and ends give him the key to the comprehension of events. Discovering human elements everywhere, he is always ready with judgments of worth—the stars move in circles because circular motion is the most perfect; the right is better than left, upper finer than lower, that which precedes more beautiful than that which follows. Thinkers in whom this aesthetic reverence is weaker than the analytic impulse—especially Democritus—seem half modern rather than Greek. By the side of the Greek philosophy, in its sacred festal garb, stands the modern in secular workday dress, in the laborer's blouse, with the merciless chisel of analysis in its hand. This does not seek beauty, but only the naked truth, no matter what it be. It holds it impossible to satisfy at once the understanding and taste; nay, nakedness, ugliness, and offensiveness seem to it to testify for, rather than against, the genuineness of truth. In its anxiety not to read human elements into nature, it goes so far as completely to read spirit out of nature. The world is not a living whole, but a machine; not a work of art which is to be viewed in its totality and enjoyed with reverence, but a clock-movement to be taken apart in order to be understood. Nowhere are there ends in the world, but everywhere mechanical causes. The character of modern thought would appear to a Greek returned to earth very sober, unsplendid, undevout, and intrusive. And, in fact, modern philosophy has a considerable amount of prose about it, is not easily impressed, accepts no limitations from feeling, and holds nothing too sacred to be attacked with the weapon of analytic thought. And yet it combines penetration with intrusiveness; acuteness, coolness, and logical courage with its soberness. Never before has the demand for unprejudiced thought and certain knowledge been made with equal earnestness. This interest in knowledge for its own sake developed so suddenly and with such strength that, in presumptuous gladness, men believed that no previous age had rightly understood what truth and love for truth are. The natural consequence was a general overestimation of cognition at the expense of all other mental activities. Even among the Greek thinkers, thought was held by the majority to be the noblest and most divine function. But their intellectualism was checked by the aesthetic and eudaemonistic element, and preserved from the one-sidedness which it manifests in the modern period, because of the lack of an effective counterpoise. However eloquently Bacon commends the advantages to be derived from the conquest of nature, he still understands inquiry for inquiry's sake, and honors it as supreme; even the ethelistic philosophers, Fichte and Schopenhauer, pay their tribute to the prejudice in favor of intellectualism. The fact that the modern period can show no one philosophic writer of the literary rank of Plato, even though it includes such masters of style as Fichte, Schelling, Schopenhauer, and Lotze, not to speak of lesser names, is an external proof of how noticeably the aesthetic impulse has given way to one purely intellectual.
When we turn to the character of mediaeval thinking; we find, instead of the aesthetic views of antiquity and the purely scientific tendency of the modern era, a distinctively religious spirit. Faith prescribes the objects and the limitations of knowledge; everything is referred to the hereafter, thought becomes prayer. Men speculate concerning the attributes of God, on the number and rank of the angels, on the immortality of man—all purely transcendental subjects. Side by side with these, it is true, the world receives loving attention, but always as the lower story merely,[1] above which, with its own laws, rises the true fatherland, the kingdom of grace. The most subtle acuteness is employed in the service of dogma, with the task of fathoming the how and why of things whose existence is certified elsewhere. The result is a formalism in thought side by side with profound and fervent mysticism. Doubt and trust are strangely intermingled, and a feeling of expectation stirs all hearts. On the one side stands sinful, erring man, who, try as hard as he may, only half unravels the mysteries of revealed truth; on the other, the God of grace, who, after our death, will reveal himself to us as clearly as Adam knew him before the fall. God alone, however, can comprehend himself—for the finite spirit, even truth unveiled is mystery, and ecstasy, unresisting devotion to the incomprehensible, the culmination of knowledge. In mediaeval philosophy the subject looks longingly upward to the infinite object of his thought, expecting that the latter will bend down toward him or lift him upward toward itself; in Greek philosophy the spirit confronts its object, the world, on a footing of equality; in modern philosophy the speculative subject feels himself higher than the object, superior to nature. In the conception of the Middle Ages, truth and mystery are identical; to antiquity they appear reconcilable; modern thought holds them as mutually exclusively as light and darkness. The unknown is the enemy of knowledge, which must be chased out of its last hiding-place. It is, therefore, easy to understand that the modern period stands in far sharper antithesis to the mediaeval era than to the ancient, for the latter has furnished it many principles which can be used as weapons against the former. Grandparents and grandchildren make good friends.
[Footnote 1: On the separation and union of the three worlds, natura, gratia, gloria, in Thomas Aquinas, cf. Rudolph Eucken, Die Philosophie des Thomas von Aquino und die Kultur der Neuzeit, Halle. 1886.]
When a new movement is in preparation, but there is a lack of creative force to give it form, a period of tumultuous disaffection with existing principles ensues. What is wanted is not clearly perceived, but there is a lively sense of that which is not wanted. Dissatisfaction prepares a place for that which is to come by undermining the existent and making it ripe for its fall. The old, the outgrown, the doctrine which had become inadequate, was in this case Scholasticism; modern philosophy shows throughout—and most clearly at the start—an anti-Scholastic character. If up to this time Church dogma had ruled unchallenged in spiritual affairs, and the Aristotelian philosophy in things temporal, war is now declared against authority of every sort and freedom of thought is inscribed on the banner.[1] "Modern philosophy is Protestantism in the sphere of the thinking spirit" (Erdmann). Not that which has been considered true for centuries, not that which another says, though he be Aristotle or Thomas Aquinas, not that which flatters the desires of the heart, is true, but that only which is demonstrated to my own understanding with convincing force. Philosophy is no longer willing to be the handmaid of theology, but must set up a house of her own. The watchword now becomes freedom and independent thought, deliverance from every form of constraint, alike from the bondage of ecclesiastical decrees and the inner servitude of prejudice and cherished inclinations. But the adoption of a purpose leads to the consideration of the means for attaining it. Thus the thirst for knowledge raises questions concerning the method, the instruments, and the limits of knowledge; the interest in noëtics and methodology vigorously develops, remains a constant factor in modern inquiry, and culminates in Kant, not again to die away.
[Footnote 1: The doctrine of twofold truth, under whose protecting cloak the new liberal movements had hitherto taken refuge, was now disdainfully repudiated. Cf. Freudenthal, Zur Beurtheilung der Scholastik, in vol. iii. of the Archiv für Geschichte der Philosophie, 1890. Also, H. Reuter, Geschichte der religiösen Aufklärung im Mittelalter 1875-77; and Dilthey, Einleitung in die Geisteswissenschaften, 1883.]
This negative aspect of modern tendencies needs, however, a positive supplement. The mediaeval mode of thought is discarded and the new one is not yet found. What can more fittingly furnish a support, a preliminary substitute, than antiquity? Thus philosophy, also, joins in that great stream of culture, the Renaissance and humanism, which, starting from Italy, poured forth over the whole civilized world. Plato and Neoplatonism, Epicurus and the Stoa are opposed to Scholasticism, the real Aristotle to the transformed Aristotle of the Church and the distorted Aristotle of the schools. Back to the sources, is the cry. With the revival of the ancient languages and ancient books, the spirit of antiquity is also revived. The dust of the schools and the tyranny of the Church are thrown off, and the classical ideal of a free and noble humanity gains enthusiastic adherents. The man is not to be forgotten in the Christian, nor art and science, the rights and the riches of individuality in the interest of piety; work for the future must not blind us to the demands of the present nor lead us to neglect the comprehensive cultivation of the natural capacities of the spirit. The world and man are no longer viewed through Christian eyes, the one as a realm of darkness and the other as a vessel of weakness and wrath, but nature and life gleam before the new generation in joyous, hopeful light. Humanism and optimism have always been allied.
This change in the spirit of thought is accompanied by a corresponding change in the object of thought: theology must yield its supremacy to the knowledge of nature. Weary of Christological and soteriological questions, weary of disputes concerning the angels, the thinking spirit longs to make himself at home in the world it has learned to love, demands real knowledge,—knowledge which is of practical utility,—and no longer seeks God outside the world, but in it and above it. Nature becomes the home, the body of God. Transcendence gives place to immanence, not only in theology, but elsewhere. Modern philosophy is naturalistic in spirit, not only because it takes nature for its favorite object, but also because it carries into other branches of knowledge the mathematical method so successful in natural science, because it considers everything sub ratione naturae and insists on the "natural" explanation of all phenomena, even those of ethics and politics.
In a word, the tendency of modern philosophy is anti-Scholastic, humanistic, and naturalistic. This summary must suffice for preliminary orientation, while the detailed division, particularization, modification, and limitation of these general points must be left for later treatment.
Two further facts, however, may receive preliminary notice. The indifference and hostility to the Church which have been cited among the prominent characteristics of modern philosophy, do not necessarily mean enmity to the Christian religion, much less to religion in general. In part, it is merely a change in the object of religious feeling, which blazes up especially strong and enthusiastic in the philosophy of the sixteenth century, as it transfers its worship from a transcendent deity to a universe indued with a soul; in part, the opposition is directed against the mediaeval, ecclesiastical form of Christianity, with its monastic abandonment of the world. It was often nothing but a very deep and strong religious feeling that led thinkers into the conflict with the hierarchy. Since the elements of permanent worth in the tendencies, doctrines, and institutions of the Middle Ages are thus culled out from that which is corrupt and effete, and preserved by incorporation into the new view of the world and the new science, and as fruitful elements from antiquity enter with them, the progress of philosophy shows a continuous enrichment in its ideas, intuitions, and spirit. The old is not simply discarded and destroyed, but purified, transformed, and assimilated. The same fact forces itself into notice if we consider the relations of nationality and philosophy in the three great eras. The Greek philosophy was entirely national in its origin and its public, it was rooted in the character of the people and addressed itself to fellow-countrymen; not until toward its decline, and not until influenced by Christianity, were its cosmopolitan inclinations aroused. The Middle Ages were indifferent to national distinctions, as to everything earthly, and naught was of value in comparison with man's transcendent destiny. Mediaeval philosophy is in its aims un-national, cosmopolitan, catholic; it uses the Latin of the schools, it seeks adherents in every land, it finds everywhere productive spirits whose labors in its service remain unaffected by their national peculiarities. The modern period returns to the nationalism of antiquity, but does not relinquish the advantage gained by the extension of mediaeval thought to the whole civilized world. The roots of modern philosophy are sunk deep in the fruitful soil of nationality, while the top of the tree spreads itself far beyond national limitations. It is national and cosmopolitan together; it is international as the common property of the various peoples, which exchange their philosophical gifts through an active commerce of ideas. Latin is often retained for use abroad, as the universal language of savants, but many a work is first published in the mother-tongue—and thought in it. Thus it becomes possible for the ideas of the wise to gain an entrance into the consciousness of the people, from whose spirit they have really sprung, and to become a power beyond the circle of the learned public. Philosophy as illumination, as a factor in general culture, is an exclusively modern phenomenon. In this speculative intercourse of nations, however, the French, the English, and the Germans are most involved, both as producers and consumers. France gives the initiative (in Descartes), then England assumes the leadership (in Locke), with Leibnitz and Kant the hegemony passes over to Germany. Besides these powers, Italy takes an eager part in the production of philosophical ideas in the period of ferment before Descartes. Each of these nations contributes elements to the total result which it alone is in a position to furnish, and each is rewarded by gifts in return which it would be incapable of producing out of its own store. This international exchange of ideas, in which each gives and each receives, and the fact that the chief modern thinkers, especially in the earlier half of the era, prior to Kant, are in great part not philosophers by profession but soldiers, statesmen, physicians, as well as natural scientists, historians, and priests, give modern philosophy an unprofessional, worldly appearance, in striking contrast to the clerical character of mediaeval, and the prophetic character of ancient thinking.