# A Brief History of Modern Philosophy/Book 4

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FOURTH BOOK
THE PHILOSOPHY OF THE ENLIGHTENMENT IN FRANCE AND GERMANY
The great philosophical systems and English empiricism affected a comparatively small circle of thinkers. But about the middle of the eighteenth century an effort was made to popularize the ideas of these solitary thinkers. This movement, which is generally spoken of as the enlightenment, assumed a more definite form in France and Germany than in England. In France, Locke's fundamental principle, that all ideas proceed from experience, furnished the basis for criticizing the existing order of things both in Church and State. The opinion generally prevailed that man had attained the climax of enlightenment and that he was now in possession of adequate presuppositions for the final solution of all the old problems or to dismiss them definitely as groundless. A new dogmatism arose, which was perhaps necessary in order to destroy the old form of dogmatism. In Germany the popularization of the Leibnitzian philosophy, with its reduction of all mental distinctions to the distinction between obscurity and clearness, was particularly influential, and the inference was drawn that enlightenment, and nothing but enlightenment, is the one thing needful. But there were minds both in France and in Germany whose thoughts were centered on the profounder presuppositions of mental life, of which neither the protagonists of the new nor the exponents of the old had the least suspicion. In this respect Rousseau in France and Lessing in Germany occupied middle ground between the opposing views—and at the same time above them.
A. The French Philosophy of the Enlightenment and Rousseau
1. In France the agitation produced by the enlightenment assumed a decidedly revolutionary character. This was due more particularly to the fact that the old order of things had here reached a greater degree of definiteness and had assumed an attitude of contempt for the new thought to a greater extent than in England and Germany, and that at the same time it was more shallow and corrupt than in the other countries. France was revolutionized by English ideas. The visit of Voltaire and Montesquieu to England at the close of the third decade of the century became a matter of epochal importance. It was not until then that the English philosophical, religious, aesthetic and political ideas became known in France and on the continent generally. Voltaire's Lettres sur les Anglais (1734) marks the beginning of a new period in French thought. Voltaire (1694–1778) was not an original thinker. But he possessed the happy faculty of stating scientific ideas and theories with brevity and clearness, and at the same time aggressively. He published a most excellent exposition of Newton's natural philosophy, and he used Locke with splendid effect in his philosophical works. With Locke's principle, that all our ideas proceed from experience, and Newton's discovery of the uniformity of nature as his basis, he criticized the theology of the Church. He does not confine himself in the controversy to logical argument, but likewise employs sarcasm and ridicule and—especially when attacking spiritual and physical oppression and intolerance—profound indignation.—The following are his most important philosophical works: Dictionnaire philosophique portatif (1764) and Le philosophe ignorant (1766).
​All ideas proceed from sensations and sensations in turn proceed from matter. What is matter? We do not know, —we are quite as ignorant on this point as on the question concerning the nature of the soul. The Creator endowed us with understanding to the end that we might thereby govern our actions, not for the purpose of penetrating into the nature of things. The eternity of matter represents the limit of our knowledge; and this rests upon the universally accepted principle that nothing can proceed from nothing. The teleology of nature is proof of the existence of God. But the presence of sin and evil in the world (facts which Voltaire describes with rare acumen in his Poeme sur le desastre de Lisbonne) makes it impossible to believe in the omnipotence of God if we wish to retain our belief in His goodness. Voltaire espouses natural religion, but opposes revealed religion by every available means (frequently of course indirectly and secretly). Voltaire now applies the principle of simplicity to the explanation of the supernatural in the same way as the thinkers of the Renaissance applied it to the natural world. He refers everything which transcends natural religion to stupidity and deception. Stupidity gives rise to the idea of the supernatural and deceivers afterwards take advantage of this stupidity in order to gain control over men by means of their superstition. The best religion is the one that contains a large measure of ethical culture, but few dogmas.
Montesquieu (1689-1755) is of greater historical significance than Voltaire. In his Esprit de lois (1748) he advocates the mutual dependence of institutions and of laws upon the natural and moral conditions of the nations. A constitution cannot therefore be transferred from one nation to another without modification. The historical ​and comparative methods enabled Montesquieu to criticize the existing social conditions incisively and systematically. His over-rapid generalizations however are unhistorical. He proposes an ideal form of the English constitution, without observing that the long period of the political development of the English people by means of self- government in smaller groups was its historical presupposition.
Condillac (1715-1780) attempted a simplification of Locke's theory of knowledge in his Traité des sensations (1754), by means of referring the whole of our conscious experience to absolutely passive sensations. Attention is nothing more than an intense sensation, which precludes the possibility of another sensation arising; memory is simply a secondary effect of sensation, and comparison consists of nothing more than the concomitant appearance of two sensations. The comparison of pleasure and pain gives rise to desires and impulses.—Notwithstanding his endeavor to eliminate every form of activity from psychology, Condillac still adheres to the Cartesian theory of the soul and the body as two distinct entities. Sensation cannot be identified with motion, and our ability to make comparisons (i. e., to be conscious of two sensations at the same moment) definitely proves that the vehicle of sensations is a simple substance. Condillac, who was a Catholic ecclesiastic, was thus able to harmonize his psychology with his theology. But the spiritualistic element of Condillac's theory was devoid of influence. His followers insisted on reducing all psychical phenomena to passive sensations.
La Mettrie (1702-1751), a physician, had even before this time substituted a thorough-going materialism for the Cartesian dualism in his famous work, L'homme machine ​(1748). The rise of temperature under the influence of enthusiasm and the mental agitation produced by fevers can only be explained on the theory that what we call the soul consists of pure matter. Sensation is an attribute of matter, just like extension and motion. The real nature of matter however transcends the power of our understanding.—Besides these materialistic theories, La Mettrie's works (Systeme d'Epicure; L'homme planta) contain interesting anticipations and suggestions of a theory of evolution. The various forms of life evolve from eternal organic germs under the influence of environment. Desire and need are the forms of energy which make for progress, and beings without needs lack the attribute of mind. Man is the highest being, because he is conscious of the greatest amount of needs.
Von Holbach (1723-1789), a German baron living in Paris, published a purely dogmatic and systematic elaboration of materialism. In his Systbme de la nature(1770) he contends that materialism is the only consistent explanation of the facts of natural science. If motion is a primary property of matter (as Toland had affirmed), and if material phenomena are only explainable by reference to material causes, it follows that it is unnecessary to assume either one or many minds distinct from matter. An appeal to mind is only a sign of ignorance. Thought or consciousness is simply the agitation of the particles of matter, a motion which is similar to fermentation, which is the common basis of all nourishment and growth, motions which are indeed imperceptible, but which are inferred from what is evident to the senses. There is but one science, physics, i. e. the theory of motion. The assumption of two kinds of nature, spiritual and material, is not only unnecessary, but positively harmful. It is ​conducive of superstition and thereby leads back again to the authority of priestcraft. Even the so-called natural religion is dangerous; for religion, no matter what the form, must necessarily have a form of worship, and the institution of forms of worship involves submission to the authority of priests. The formation of the concepts of deity is the product of a profound politics on the part of the theologians, those fabricateurs de la divinité!
Helvetius ' (1715-1771) theory of the original equality of all men, as respects nature and talent, is in a certain sense closely related to Condillac's doctrine of the passivity of all psychic life. All distinctions are due to external causes, to education in its widest sense, i. e. to all the influences which affect us. Education is responsible for the tendency which claims our interest and attention. No two men ever receive precisely the same kind of education. The only motive is self-interest, and whether it shall be actuated by great or small ideas depends entirely upon education (De l'esprit, 1758). Helvetius' posthumous work De l'homme(1773) is a polemic, based on the foregoing presuppositions, against the distinction between private and public interests, a distinction which is favored by despotic forms of government, and to which he attributes the misfortune of his native land. This last observation is of fundamental importance for the understanding of Helvetius. He was a tender-hearted, patriotic spirit, who devoted his vast fortune, acquired as Farmer- general, to the service of literature and philanthropy.
The profoundest thinker of this whole group was Dems Diderot (1713-1784), renowned as the energetic editor of the great Encyclopedia on account of which the French philosophers of the Enlightenment were called Encyclopedists. Diderot could only express his own ideas ​indirectly in the Encyclopedia. In the Interpretation de la nature (1754) we find ideas concerning the continuous evolution of life on the earth which are very similar to those of La Mettrie. He was profoundly influenced by Leibnitz, especially in the matter of his emphasis of the concepts of continuity and force. The two dialogues, written in 1769, but not published until 1830, Entretien entre d'Alembert et Diderot and Reve d'Alembert, contain his most ingenious ideas. In direct contradiction of La Mettrie and Holbach, Diderot denies that the psychical processes can be adequately explained as a mere effect of the interaction of material elements. A transposition of atoms can never produce consciousness. The only possible explanation of the origin of psychic life is on the presupposition of the presence of germs or dispositions in the lower orders which can be developed to conscious life in the higher orders by means of a process of progressive integration. Diderot attributes sensibility to everything in nature, but he makes a distinction between potential and actual sensibility (sensibilite inerte, sensibilite active). He likewise emphasizes the difficulty of conceiving how a unitary consciousness could be constructed from a great variety of psychical elements. He does not solve the problem. But he seems inclined to adhere so tenaciously to the idea of continuity, as to leave no room for any actually distinct elements.
2. Jean Jacques Rousseau (1712-1778) was intimately associated with the Encyclopedists for a while. His rupture with them—to which, besides their fundamental differences, personal motives certainly contributed not a little—was an event in the history of civilization, a sign that a new problem was forcing its way to the surface. Just as Hume's problem pertained to the possibility of ​science, so Rousseau's problem raised the question concerning the value of civilization.
Rousseau was born in Geneva. His restless spirit, chafing under the restraints of social custom, impelled him to a life of romantic travel and adventure, turning up in Paris in the year 1741, where he became a friend of Diderot and Holbach. The thought of the contradiction between nature and culture (Kultur), containing the principles of far-reaching consequences, caused him to leave Paris in order that he might live in the country, and the rupture with his Encyclopedist friends soon followed. His writings made him a fugitive and vagabond. He was not even able to find a permanent residence in Switzerland. During his latter years his suspicions and illusion of persecution developed a decidedly morbid character. He spent his last years in seclusion in France.
a. His first essays (Discours sur les sciences et les arts, 1750, and Discours sur I'origine et les fondements de I'in- egalite parmi les hommes, 1755) draw a sharp contrast between nature and culture. Several different classes of ideas are vaguely combined in Rousseau's earlier theories of nature, but his ideas are gradually clarified by constant reflection, so that his theory of nature as it appears in his masterpiece, Emile (1762), is very clear. In the third dialogue of the remarkable essay entitled Rousseau juge de Jean Jacques he calls attention to the fact that his works form a connected series, which leads back step by step to certain fundamental principles. Whoever would wish to read him synthetically, he says, must therefore begin with Emile. His object in the first essays was to criticize the existing state of culture and to remove the obstacles which impede natural development. The direct and positive elaboration of his principles must necessarily ​come later. The paradoxes to which his introductory theories had led would likewise then be removed by the positive presentation.
Three distinct classes of ideas (as may be seen from the preface to the Discours de l'inegalite) influenced Rousseau from the first in the formation of his theory of nature: a theological, a zoological and a psychological. Nature is a divine product, but civilization is a human product. The state of nature is therefore a state of perfection, of "heavenly and majestic simplicity." We are here reminded of the Garden of Eden. But other passages describe the state of nature as a life of pure instinct, in which no needs beyond the purely physical exist, and in which reflection and imagination are wholly undeveloped. Rousseau passes from the department of theology to that of zoology without being aware of it. The real source of his theory of nature however is psychological. As a matter of fact Rousseau is not concerned about any far distant past, but with a matter which he was able to discover within his own soul. "Nature" consists of the immediate, total energy of life, spontaneous development, rather than the restraint and complexity which civilization so readily brings with it. Man has a natural tendency to assert himself, to develop aptitudes and impulses. And this spontaneous tendency is so powerful, the hidden source of life is so rich, that self-assertion in itself in nowise contradicts sympathy, or resignation and self-denial. The individual originally made no distinction between himself and others. The stream which issues from within extends to all beings which are similarly constituted to the individual himself: La force d'une ame expansive m'identifie avec mon semblable. Kindness and love are therefore natural. Even religious emotion—in the form of gratitude, admiration and ​reverence—is a natural consequence of this spontaneous expansion.
However when the distinction between individuals makes itself felt, due to the rise of comparative reflection, self-assertion (amour de soi), in itself free and noble, becomes egoism (amour propre). Dependence, discontent, vanity, envy and lust for power manifest themselves. And to this must be added the division of labor which social life evolves. Faculties and accomplishments are specialized and the perfect, harmonious and all-round development of personality is suppressed. Mental life is broken to pieces and rendered artificial. With Rousseau the demand to return to nature is therefore identical with the demand that man shall once more become a unit; Rendez I'homme uni—This sense of completeness and unity, experienced in the freedom of nature with which he became so well acquainted during the vagabond journeys of his youth, grew upon Rousseau with an extraordinary power and freshness. He is the first to have given enthusiastic expression to the genuine joy to be found in the solitude of nature and in the appreciation of the beauties of nature.
The more profoundly he reflected upon his ideas the clearer it became to Rousseau (as had also been the case with Shaftesbury before him) that the contradiction between nature and culture could be only a matter of degree. When he declaims against science and art, he really means only the science and art of his own age which was so utterly devoid of originality, whilst he praised the great investigators of the Renaissance and the seventeenth century. Even genius is likewise a form of spontaneous development, rather than the product of imitation or discipline. Culture is a good thing and natural in itself, so long as it harmonizes with the stage of human development; indeed ​it then even becomes a means to the proper development of natural powers. A given type of culture however can never be transferred from one people to another without modification. There is no culture which is adapted to all men, to all ages and in all places. Rousseau vigorously opposes the opinion that the Parisian enlightenment and culture of the middle of the eighteenth century should be regarded as typical of culture in general; and it was exceedingly vexatious to him that Voltaire and the Encyclopedists were endeavoring to introduce this culture into his beloved Switzerland. (The author of this text-book has endeavored to elaborate this conception of Rousseau's theory of nature more fully in his book entitled Rousseau und seine Philosophie.)
b. The psychology then in vogue still retained, in adherence to Aristotle, the twofold division of psychical elements into intelligence and will, the theoretical and the practical faculties. The question of a different division of the mental functions was agitated to a certain extent by Spinoza and the English psychologists of the eighteenth century (Shaftesbury and his disciples). But the real credit for securing the recognition of feeling as manifesting a distinct phase of psychic life nevertheless belongs to Rousseau. As a matter of fact, feeling possesses the character of immediacy and expansion which Rousseau regards peculiar to nature, whilst cognition consists of comparison, volition of preference or choice. It is feeling, furthermore, according to Rousseau, that constitutes the real value of human life. It is almost wholly independent of knowledge; in its climaxes, when it rises to ecstasies, it excludes clear ideas entirely. And it changes less rapidly than knowledge. (See, besides Emile: Reveries d'un promeneur solitaire.) ​c. Rousseau makes a strong defense for Nature in his pedagogy. He decidedly prefers to leave education to nature, because he has implicit confidence in the growth and the natural improvement of the various organs and faculties. The fact however that children are constantly exposed to external social influence imposes the necessity of protecting them against harmful impressions, so as to give free course to nature. Education should be predominantly negative, i. e. it should rather consist in the removal of obstacles than in the making of positive impressions. His splendid apology for Emile,—Lettre a Beaumont, archeveque de Paris,—contains a full development of this idea of a negative pedagogy. Its supreme necessity rests upon the fact that we are utterly ignorant of the nature of the child at the beginning of its career. We cannot begin positive discipline until after we have become acquainted with the disposition of the child by means of observation. The period of infancy is quite as distinct and important a part of life as the later periods and it should be regarded as more than a mere preparation for the latter. The child should therefore be as free from restraint as possible, giving itself to the joy of life without reserve. It were decidedly the best if the child could acquire all of its knowledge independently, discover all the established truths for itself.
The negative period of discipline is an exceedingly difficult task. It requires the pedagogue to be observant, alert, inspiring and yet reserved and self-denying, all at the same time: tout faire, en ne faisant rien!—This idea represents one of the most important modifications in the history of pedagogy.
d. In his attitude towards religion Rousseau presents a very peculiar contrast to Voltaire, even though both ​practically agree in their religious ideas,—the dogmas of "Natural Religion." In agreement with Voltaire, Rousseau believes in a personal God, who is good, but not omnipotent; and he likewise explains the fact of evil and sin by reference to the resistance of matter. Like Voltaire, he also repudiates the materialism of La Mettrie and Holbach. But he nevertheless experienced a profound antipathy towards Voltaire's position. For him, the roots of religion are to be found entirely within the realm of the emotions. As we have observed, it springs from the yearning for self-assertion and self-development. This yearning is capable of such intensity as to transcend the possibility of satisfaction by any finite object. It is especially true in the solitude of nature that, according to Rousseau, this yearning rises to an affection, to an ecstasy of love, of admiration, of superabundant life. No idea is commensurate with religion; it transcends every conceivable object, every effort of expression. J'étouffle dans l'univers, says Rousseau (in a letter to Malesherbes). The fact that religion proceeds from the "deeper emotions": j'ai laissé là la raison, et j'ai consulté la nature, c'est-à-dire le sentiment intérieur qui dirige ma croyance (Letter to Vernes).
However, even though religion has its origin in a source which is independent of reason, according to Rousseau, it is still not in conflict with reason. He is convinced that the fundamental truths of natural religion can be established by rational proofs. He regards materialism absurd because neither motion, nor the uniformity of nature, nor the origin of psychic life is capable of explanation from mere matter. In his philosophy Rousseau is a Cartesian. But he does not believe in a creation out of nothing. Nothing can come into being through a sheer act of will. ​And the only way of explaining the evil and the sin in the world is on the assumption of a constant resistance to the divine purposes; i. e. the eternity of matter.
Rousseau objects to the positive religions on the ground that they set up authorities and books between man and God, and that they detract from the dignity of the divine relationship by their "clumsy worship." He regards himself a Christian, even though he cannot accept the dogmas and miracles.
Rousseau elaborates his religious ideas in fullest detail in the Emile, in the famous section entitled "Profession de foi du Vicaire Savoyard." He would postpone religious instruction until the adolescent period, because children should not accept ideas which are incomprehensible to them. And the aim of religious instruction should be above all else to satisfy the needs of the heart. "What does it matter to me whether the world is eternal or created?" In the Contrat Social he advocates natural religion as the state religion. Here, speaking from the viewpoint of the state, he takes strong ground against Christianity, because it regards man's highest duty and his highest aim to pertain to the next world and thus paralyzes the energy which the state must require of its citizens.
e. Rousseau elaborated his political ideas in the Contrat Social (1762). He advocates popular sovereignty with an enthusiasm unknown since the days of Althusius. The universal will (la volente generale, rather than la volonte de tous) must be the final court of appeal. It represents the inner yearning, the governing tendency of the people which is concerned for the common interests, the welfare of the whole as well as the individual in the constantly changing generations. It finds expression in the ​sentiment of patriotism and is analogous to the desire for self-assertion (amour de soi) in the individual. Subjection to it does not involve any limitation of liberty, because it combines the wills of all the individuals: each individual is membre du souverain.
Rousseau distinguishes between the form of the state and the form of the government, just as Bodin and Althusius had done. The former can be only one, since sovereignty always belongs to the people; but the forms of government vary with the stage of culture and the character of the people. Rousseau had a decided preference for small states, for the simple reason that in them, custom and popular usage, the spontaneous expression of the popular will, could shape the course of public policies without conscious interference and without formal legislation. These offer the most favorable conditions for the development of sympathy and humanity. They furnish a larger degree of liberty and it is unnecessary that governmental authority should be so rigid. Furthermore, the citizens can here maintain their control of the affairs of the government more easily than in a larger state. The only way a great nation can maintain its freedom is by forming a union of a number of smaller states.
The unlimited division of labor is detrimental to society as a whole. This, as we have observed, is the real source of the problem of civilization, which, for Rousseau, is identical with the social problem. He was the first to form a clear conception ef the social problem. The division of labor results in a one-sided development of the individual, producing a state of unnatural dependence on others. Rousseau extols rural life because the division of labor is much farther advanced in the cities, and the country ​likewise brings one closer to nature. He regards the countryfolk as really constituting the nation and looks with grave apprehension on the strong drift from the country to the city.
B. The German Philosophy of the Enlightenment and Lessing
1. Christian Wolff (1679–1754) was the first to give a detailed exposition of modern philosophy in the German language. He popularized the philosophy of Leibnitz. The wide range of his systematic writings drove scholasticism out of the advanced schools of Germany. However, it was not metaphysical idealism and the doctrine of monads that was prominent in his system, but the theologically more acceptable theory of preëstablished harmony. But even this doctrine made him a martyr. King Frederick William I dismissed him from his professorship at Halle on account of his apparent fatalism, and even drove him into exile on the short notice of forty-eight hours. He went to Marburg, but was recalled to Halle during'the first year of Frederick II.—His Vernünftige Gedanken von Gott, der Welt, der Seele der Menschen, auch allen Dingen Überhaupt (1719) contains a general outline of his philosophy. His attempt to derive the principle of sufficient reason from the principle of contradiction—because he thinks that origin from nothing involves a contradiction—brings the dogmatico-rationalistic philosophy to its culmination in him. Many of his disciples nevertheless tried to accord due recognition to experience. This led to a combination of the Lockian and Wolffian philosophies in a more or less eclectic fashion. They were especially disposed to place great emphasis on empirical psychology (in which indeed Wolff himself was a famous ​example). In relation to psychology metaphysics fell more and more into the background.
The psychology of the enlightenment, in its more characteristic development, held that the clearness or obscurity of ideas is all that it is possible to assert. In Germany however, like Shaftesbury in England and Rousseau in France, Sulzer (in the Essays of the Berlin Academy, 1751–2) and Mendelssohn (Briefe über die Empfindungen, 1755) held that the sentiments (above all the aesthetic sentiment) possess an independent significance and that they cannot be resolved into purely intellectual elements. Kant (in his writings during the sixties) and Tetens (Philosophische Versuche über die menschlische Natur und ihre Entwickelung, 1777) likewise adopt this view.
The eighteenth century was not only the century of enlightenment, but likewise the century of sentimentality. The natural sentiments demand satisfaction just as well as the natural understanding. And it frequently happened that these two tendencies came into conflict with each other, just as in the "storm and stress period," the period of ferment, whence the most brilliant products of art and of science were ultimately destined to proceed. On the other hand, however, the ferment did not permeate public life there as it had done in France. Neither were the religious antitheses so sharply drawn in Germany as in France. Protestantism had already departed from barren orthodoxy through the influence of pietism, and adherents to rationalism were even found within the church itself. Influential churchmen accepted the Wolffian philosophy, frequently (as e. g. at Königsberg) in its characteristic combination with pietism.
Moses Mendelssohn (1722–1786), a Jewish author noted for clearness and elegance of style, a disciple of Wolff and ​Locke, who defended the doctrine of immortality (Phädon, 1767) and the existence of God (Morgenstunden, 1786) on rational grounds, exerted a profound influence on the worldly classes. Mendelssohn is convinced that the dogmatics of Judaism contain nothing which transcends natural religion (Jerusalem, 1783). Many Protestant theologians likewise held similar views with reference to Christianity. It was only in exceptional and isolated cases that the relation between natural and positive religion became more hostile. Thus, for example, J. Chr. Edelmann (1698-1767), who has given an interesting account of his doctrinal evolution in his Autobiography (published 1849), passed from orthodoxy to pietism and finally to a Spinozistic type of rationalism. He translated "Logos" at the beginning of the Gospel of John "Reason," and, like Spinoza, he regarded God only as the immanent, not as the transcendent cause of the world. The only way in which he could find true religiosity in the biblical writings was by historical criticism and symbolic interpretation. Professor Reimarus (1694-1768) of Hamburg, the author of the Wolfenbüttel Fragments published by Lessing, was unable to conceive this relation so simply and harmoniously. He thinks that the human understanding and conscience are in irreconcilable conflict with the content of the Scriptures. Revelation is a physical and moral impossibility. The only possible explanation of the origin of the biblical traditions is on the hypothesis of a series of self-deceptions.
The German philosophy of the enlightenment did not confine itself to psychology and the philosophy of religion, but was likewise active in the department of epistemology. C. A. Crusius (1712-1775) showed that the distinction between sense-perception and pure thought is not identical ​with the distinction between obscure and clear conception; sense-perception can likewise be perfectly clear. He makes a sharp distinction between the ground of cognition and the ground of reality, and criticizes Wolf's attempt to establish the principle of causality by purely logical methods. He also exposes the error at the root of the ontological argument (Entwurf der notwendigen Vernunft- wahrheiten, 1745). In the problem of methods, J. H. Lambert (1728-1771) drew a sharp and clear distinction between the analytical and the constructive methods in philosophy (Neues Organum, 1764). J. N. Tetens (1736-1805) (in the work mentioned above) finally demonstrated that every act of the intellect, just as every act of attention, at once assumes a relation of difference or similarity.—These three investigators are Kant's immediate predecessors. Tetens may even have had access to Kant's earlier writings.
2. It is evident from the foregoing presentation that the so-called philosophy of the enlightenment contains many implications which transcend its essential doctrines. But Gotthold Ephraim Lessing (1729-1781) stands out especially as the thinker of the German enlightenment who projects himself beyond the conflicting antitheses of the age. Despite his wide divergence from Rousseau as respects character and talent, his position in the history of thought is nevertheless analogous. As a matter of fact, he was not a productive writer himself, but he had a keen and fine sense for originality in thought as well as for that internal consistency, which can never be exhausted in the definitely expressed forms of life. His attitude towards both the rationalists and the orthodox was therefore that of a critic. As a theological critic he appealed to primitive Christianity which is older than the much discussed Bible ​(Über den Beweis des Geistes und der Kraft). He likewise places the everlasting search for truth upon a higher plane than the slothful possession of it (Duplik). The continuity of spiritual evolution does not consist in results and dogmas, but in the inner strivings to which the former owe their origin.—In aesthetics he is likewise guided by the sense for the original and characteristic. In his Hamburgischen Dramaturgie—contrary to the dominant classicism —he refers to Shakespeare as the unrivalled model of dramatic poetry, and in his Laokoön he attempted to define the sphere of sculpture and poetry.
Lessing's own religious attitude is best described by the statement that it is impossible to base our knowledge of the eternal uniformity of reality upon particular historical events. The various positive religions must be understood as stages of human spiritual evolution, or, as Lessing expresses it figuratively, as disciplinary forces. Revelation bears a relation to the human race similar to that of education to the individual. The Old and New Testaments are "the primers of the human race." The time will come when such books will be unnecessary. For the present it is important that the pupil should regard his Primer as the highest science,—but the third kingdom, the new everlasting Gospel will come (Erziehung des Menschengeschlechts,—Gespräche über die Freimaurer).
From the purely philosophical point of view Lessing (according to Jacobi's account in his Briefe über die Lehre des Spinoza) is closely related to Spinoza; if he were to name himself after anyone, he knows of no one else more suitable. He wanted a purely natural theory of the universe and of life, free from any transcendental leaps. (Cf. Chr. Schrempf: Lessing als Philosoph., 1906.)