Thomasius (1655-1728) was one of the most influential teachers of his day. He was Professor first at Halle and afterwards at Leipzig, where, on account of the boldness of his utterances, he roused the suspicion and resentment of the authorities. He was distinguished as being the first academic teacher who gave his lectures in the German language, a practice followed by Wolff. In his freedom from Scholastic forms of expression and methods of reasoning, in his constant attempt to bring science into touch with common life, as well as in his demand for religious toleration, he exhibited the characteristic features of the Enlightenment. Educated as a lawyer, he was greatly influenced by his study of Grotius and Pusendorf, who directed his attention to political and social questions. Philosophy with him resolves itself into worldly wisdom, the object of which is to further the general happiness of man. Peace belongs to those who free themselves from ambitious desires and unruly passions and devote themselves to the cultivation of virtue—"rational love." He is more of an enlightener than a philosopher, a champion of liberty rather than a promoter of science. The goal of philosophy is not so much wisdom as well-being, and the means by which it is to be attained is common sense. Reason is the test of all truth. He divides his practical philosophy into three parts—natural right, or justice; politics, which has to do with decorum; and ethics, which treats of honesty. In his natural right he treats of the world and of man. The world consists partly of visible and invisible things. The visible, he names bodies; the invisible, powers. All bodies have some kind of powers, and the higher we rise in nature the higher are the powers. Man consists of both body and powers. Through his higher powers he comes into relation with his fellowmen. The principle of justice lies in the requirement, to act towards no one as we would not have him act towards us. The principle of politics or "decorum" is so to act towards another as we should wish him to act towards us. And the principle of ethics or "honesty" is, to do that ourselves which we should commend as praiseworthy in others. All positive right is a human ordinance, a need of our nature taught us by experience. Whether it has its ultimate ground in God is a matter for theologians to discuss.
With the name of Thomasius that of Tschirnhausen is closely allied (1651-1708). More scientific in his method, he is not less of an eclectic in his attempt to reconcile rationalism with empiricism. He was born in Lausitz. He studied at Leyden, where he came under the personal influence of Spinoza. He also became the friend of Leibnitz, and corresponded with him on matters of philosophy. His principal work, Medicina Mentis, professes to be a general introduction to scientific knowledge. While convinced of the necessity of applying the method of mathematics to all departments of knowledge, he believes, at the same time, that all knowledge is derived from experience, and that deduction must be preceded by the observation and collection of facts. When we proceed in this way we become possessed of four fundamental facts: 1. That we are conscious of a variety of things; 2. that of these some please and some displease; 3. that some things are comprehensible and others are not; 4. that we receive pictures of external things through our senses, imagination, and feelings. From the first of these facts we derive our notion of mind; from the second the will; from the third the understanding; from the fourth the imagination and the body. Corresponding to these, there are four kinds of knowledge—knowledge in general, morals, logic or the science of the understanding, and physics or the science of experience. From the facts of experience we advance to notions, and then proceed by the way of deduction from the general to the particular. Perception and conception, therefore, sensations and ideas, are necessary to the formation of all knowledge. Truth is what can be comprehended by the understanding, which of itself cannot err, though it may be misled -by the false notions of the imagination. The only true method of reasoning is the mathematical, the method of Descartes and Spinoza. The most important of all sciences, on which, indeed, all the others rest, is Natural Philosophy or Physics. All other departments of knowledge are more or less obscured by the phantasies of the imagination. Let us only attain to clear notions of the laws of nature, and right ideas of our relations to God and man must follow.
Tschirnhausen was an acute and suggestive thinker, but, unfortunately, he did not live to complete his Physics, which was to have been the second part of his Medicina Mentis.
But much greater in philosophic importance and exercising a far wider and more lasting influence than either of the two men just mentioned is a name which is invariably associated with that of Leibnitz, and was regarded with unusual respect for nearly a century—Christian Wolff.
Wolff (1679-1754), the disciple and systematizer of the philosophy of Leibnitz, was born at Breslau towards the end of the seventeenth century. He was destined for the church, but showed an early aptitude for mathematics and speculative science. In his student days he was much impressed by Tschirnhausen's Medicina Mentis, and while a college tutor at Leipzig he attracted the notice of Leibnitz, by whose influence he was appointed successor to Thomasius in Halle. The eloquence of his lectures delivered in German, the clearness and order with which he marshalled his thoughts, the moral tone and practical character of his teaching, as well as the general novelty of his views, soon won for him a wide popularity, and his class-room was filled to overflowing. But his alleged negative attitude to Revealed Religion roused the suspicion of his theological colleagues, Frank and Lange, who belonged to the pietistic circle which largely prevailed in Germany at this time. The feeling rose so high that Fried. Wilhelm I. was induced to depose him from his chair and banish him from Halle. After teaching for a time in Marburg, he was recalled to Halle in 1740 by Frederick the Great, a warm admirer of his philosophy. Here he continued to teach with growing influence and honour till his death in 1754.
The school of the Leibnitz-Wolffian philosophy became the centre of scientific life in Germany during the eighteenth century, though it is somewhat difficult for us now to discover the secret of its power. Wolff's system is essentially that of Leibnitz, and his merit chiefly lies in the methodical development of his master's ideas, in the rounded completion and encyclopedic character of his philosophy, as well as in the popular expression of it in the current language of the people. But the originality and subtlety of thought, the bold imaginative power and inventive faculty which characterized Leibnitz are totally wanting in Wolff. He was not the man to open a new path for speculation, but he possessed the gift of popularizing the thoughts of another and making them accessible to his contemporaries. It must be admitted, however, that while he formulated the system of Leibnitz with clearness and consistency, he eliminated from it all its higher truths and richer suggestions, and reduced it largely to a common-place collection of definitions. It has been frequently pointed out that Wolff's philosophy degenerated into a dry and empty formalism. It is a system of analysis and enumeration. While Wolff proceeds from the simplest notions to the more general, and from the abstract to the concrete, there is no real evolution of thought. He deals, indeed, with the entire compass of philosophy, but the subjects are simply placed in a continuous succession without any attempt to show their inner connection or rational development. It is the philosophy of the enlightenment, reason is the highest type of judgment concerning truth, and dissection and analysis are its methods. Intellectual clearness is the test of truth; confusion and mystery the enemies of all progress.
Philosophy, according to Wolff, is the science of the possible, and the possible is that which involves no contradiction. The whole realm of the knowable is, therefore, the field of philosophy. Nothing is too insignificant for Wolff to consider. Everything that exists claims a place and calls for an explanation in his system. He deals with the minutest details of building and sanitation not less than with the attributes of God.
He accepts Leibnitz' distinction between necessary and actual truths, and he accordingly divides all philosophy into two parts—Theoretic and Practical. Before dealing, however, with these two divisions, he treats of Logic, in which he considers the laws of evidence, the criterion of truth, the degrees of certainty, opinion, belief, and knowledge, the nature of conceptions and syllogisms, and the distinction between à posteriori and à priori knowledge.
The speculative or theoretic part of philosophy, Metaphysics, is subdivided into Ontology, Cosmology, Psychology, and Theology. Practical philosophy, on the other hand, branches into Ethics, Economics, and Politics.
1. Ontology deals with the grounds of Being, the categories or radical notions of all thought, as Aristotle called them. But he makes no attempt to show their inner connection. He simply offers a bare enumeration of some of our primal ideas. He begins with the idea of contradiction, according to which the same thing cannot at once be and not be. From this law he deduces that of the Sufficient reason. There is an absolute distinction between Nihilum and aliquid, nothing and something. The intermediate state of becoming, which formed an important element in Greek as well as in later thought, has no place in Leibnitz' system. The notion of Possibility comes next. That is possible which involves no contradiction. Distinguished from the merely possible is the Necessary, the opposite of which is self-contradictory. By the help of the conceptions of the impossible and the possible he reaches the proposition that only what is completely determined is real, and that only what is real is individual. Wolff proceeds in the second part of his Ontology to deal with the various kinds of individuals or existences. These are either simple or complex. To the latter must be attributed extension, time, space, motion, etc. But none of these can be applied to simple existences. They are really units or monads. While Wolff ascribes to them power, he denies that they have the attribute of perception. Thus what Leibnitz called souls become in the hands of Wolff simply atoms.
2. Cosmology, which is the basis of physics, deals with the world as a whole—the totality of things in time and space. Since all changes in things are effected by motion, the world is a machine, and may be likened to a clock, all the works of which are necessary. The ingredients of the world can neither be increased nor diminished. While the world exists in time, and God is above time, the world cannot be eternal in the same sense that God is eternal. The component parts of the world are called bodies, small substances, which possess inherent motive-force. Wolff treats in this department also of the teleological reason of the world. Everything must be considered according to the causes that produce it, on the one hand, and according to the end it serves on the other. It is not enough, therefore, to give a mechanical explanation of the world. We must examine it from the point of view of end or purpose. This must be the best of all worlds, not merely because God has made it, but because it best serves the highest conceivable purposes. And the perfection of the world consists in this, that all things in it, good and bad alike, combine in bringing about one end, the good of the whole.
3. Psychology treats of the soul of man as simple substance. The fact of consciousness is the distinguishing mark of the soul through which it knows itself and other things. The thinking being is simple and incorporeal. It has the power of continually altering itself, from which arise all the faculties of knowledge. These Wolff divides into two classes,—inferior and superior. The inferior embrace sensation, imagination, fancy, and memory. While the superior include attention, understanding, reason. Under the head of sensation he discusses the relation between body and soul, and asserts that the only tenable explanation is that of a Pre-established Harmony. The freedom of the will consists in power to choose what seems preferable, but that we may know what is truly preferable, knowledge is required.
In his practical philosophy Wolff shows more independence than in his theoretical. Reason affords the principle of direction for the will. Good is good of itself, and would be so even if there were no God. Perfection and not happiness is the aim of life.
His Ethics has to do with man in his individual capacity, his virtues, duties to himself, and his aims in life. In developing his moral theory he distinguishes between a man's duties to himself, his duties to others, and his duties to God. His duties to others rest on the apostolic rule that we can only attain to perfection by mutual and reciprocal activity, and that in the furtherance of this end it is the duty of each to help his neighbour. Under the duties to God he designates "those acts whose motives are divine perfections." He does not thereby mean that we can actually contribute to the perfection of God. But by honouring His laws, as revealed in nature and life, by our actions, we do in a sense fulfil His perfection.
In the Economics he discourses in a genial and practical way of family life, the relations between husband and wife, parents and children, masters and servants; while in his Politics he treats of man as a member of the State, dealing with property, contract, etc. Through the contract which individuals make for mutual support and security there arises the State, the well-being and peace of which are the highest ends which those who live in it can pursue. It is not necessary to follow Wolff here into the minute details of the constitution and government of the ideal State. As we have said, the merit of Wolff is his completeness. Nothing is overlooked. If his ethical and political philosophy is full of much homely sagacity, it is also, it is to be feared, somewhat prolix and commonplace.
It will thus be seen that the system of Wolff is but a faint imitation of that of Leibnitz, leaving out all that was distinctive and suggestive of further development. He accepts Leibnitz' doctrine of monads, but rejects the idea of their perceptive or representative character, by which alone they were capable of relation with the complexity of things, with the result that the individual essences of Wolff sink into mere atoms and the unity of the world is simply a mechanical composition of unrelated particles. Again, in his treatment of the relation of God to the world, he sometimes regards God as an individual similar to but greater than man, and sometimes as a substance wholly distinct. Thus he oscillates between a purely atomistic material view of the world and a universal or pantheistic. Finally, while he adopts Leibnitz' theory of Pre-established Harmony, it becomes in his treatment merely an external combination of soul and body, and has no relation with the rest of his system.
It was not perhaps wonderful that a philosophy whose chief commendation was its clearness and method should attract many adherents, and that a system of thought so practical and homely, dealing with every variety of subject, should at length permeate the various classes of the community and give rise to what has been called "a people's philosophy." We thus find that under the influence of Wolff there sprang up in Germany during the second half of the eighteenth century a series of writers who gave to philosophy a popular turn. It is almost impossible to group them into a school, though the period has been called more especially "the German Enlightenment."