Friedrich Heinrich Jacobi was born at DÜsseldorf in 1743. His father destined him for a merchant. After he had studied in Geneva and become interested in philosophy, he entered his father’s mercantile establishment, but afterwards abandoned this business, having been made chancellor of the exchequer and customs commissioner for Cleves and Berg, and also privy councillor at DÜsseldorf. In this city, or at his neighboring estate of Pempelfort, he spent a great part of his life devoted to philosophy and his friends. In the year 1804 he was called to the newly-formed Academy of Sciences in Munich. In 1807 he was chosen president of this institution, a post which he filled till his death in 1819. Jacobi had a rich intellect and an amiable character. Besides being a philosopher, he was also a poet and citizen of the world; and hence we find in his philosophizing an absence of strict logical arrangement and precise expression of thought. His writings are no systematic whole, but are occasional treatises written “rhapsodically and in grasshopper gait,” for the most part in the form of letters, dialogues, and romances. “It was never my purpose,” he says himself, “to set up a system for the schools. My writings have sprung from my innermost life, and were the result of that which had taken place within me. In a certain sense I did not make them voluntarily, but they were drawn out of me by a higher power irresistible to myself.” This want of an inner principle of classification and of a systematic arrangement, renders a development of Jacobi’s philosophy not easy. It may best be represented under the following three points of view:—1. Jacobi’s polemic against mediate knowledge. 2. His principle of immediate knowledge. 3. His relation to the cotemporaneous philosophy, especially to the Kantian criticism.

1. Spinoza was the negative starting point of Jacobi’s philosophizing. In his work “On the Doctrine of Spinoza, in letters to Moses Mendelssohn” (1785), he directed public attention again to the almost wholly forgotten philosophy of Spinoza. The correspondence originated thus: Jacobi made the discovery that Lessing was a Spinozist, and announces this to Mendelssohn. The latter will not believe it, and thence grew the farther historical and philosophical examination. The positive philosophic views which Jacobi exhibits in this treatise can be reduced to the following three principles: (1) Spinozism is fatalism and atheism. (2) Every path of philosophic demonstration leads to fatalism and atheism. (3) In order that we may not fall into these, we must set a limit to demonstrating, and recognize faith as the element of all metaphysic knowledge.

(1.) Spinozism is atheism, because, according to it, the cause of the world is no person—is no being working for an end, and endowed with reason and will—and hence is no God. It is fatalism, for, according to it, the human will regards itself only falsely as free.

(2.) This atheism and fatalism is, however, only the necessary consequence of all strictly demonstrative philosophizing. To conceive a thing, says Jacobi, is to refer a thing to its nearest cause; it is to find a possible for an actual, the condition for a conditioned, the mediation for an immediate. We conceive only that which we can explain out of another. Hence our conceiving moves in a chain of conditioned conditions, and this connection forms a mechanism of nature, in whose investigation our understanding has its immeasurable field. However far we may carry conception and demonstration, we must hold, in reference to every object, to a still higher one which conditions it; where this chain of the conditioned ceases, there do conception and demonstration also cease; till we give up demonstrating we can reach no infinite. If philosophy determines to apprehend the infinite with the finite understanding, then must it bring down the divine to the finite; and here is where every preceding philosophy has been entangled, while it is obviously an absurd undertaking to attempt to discover the conditions of the unconditioned, and make the absolutely necessary a possible, in order that we may be able to construct it. A God who could be proved is no God, for the ground of proof is ever above that which is to be proved; the latter has its whole reality from the former. If the existence of God should be proved, then God would be derived from a ground which were before and above him. Hence the paradox of Jacobi; it is for the interest of science that there be no God, no supernatural and no extra or supramundane being. Only upon the condition that nature alone is, and is therefore independent and all in all, can science hope to gain its goal of perfection, and become, like its object itself, all in all. Hence the result which Jacobi derives from the “Drama of the history of philosophy” is this:—“There is no other philosophy than that of Spinoza. He who considers all the works and acts of men to be the effect of natural mechanism, and who believes that intelligence is but an accompanying consciousness, which has only to act the part of a looker-on, cannot be contended with and cannot be helped till we set him free from his philosophy. No philosophical conclusion can reach him, for what he denies cannot be philosophically proved, and what he proves cannot be philosophically denied.” Whence then is help to come? “The understanding, taken by itself, is materialistic and irrational; it denies spirit and God. The reason taken by itself is idealistic, and has nothing to do with the understanding; it denies nature and makes itself God.”

(3.) Hence we must seek another way of knowing the supersensible, which is faith. Jacobi calls this flight from cognition through conception to faith, the salto mortale of the human reason. Every certainty through a conception demands another certainty, but in faith we are led to an immediate certainty which needs no ground nor proof, and which is in fact absolutely exclusive of all proof. Such a confidence which does not arise from arguments, is called faith. We know the sensible as well as the supersensible only through faith. All human knowledge springs from revelation and faith.

These principles which Jacobi brought out in his letters concerning Spinoza, did not fail to arouse a universal opposition in the German philosophical world. It was charged upon him that he was an enemy of reason, a preacher of blind faith, a despiser of science and of philosophy, a fanatic and a papist. To rebut these attacks, and to justify his standpoint, he wrote in 1787, a year and a half after the first appearance of the work already named, his dialogue entitled “David Hume, or Faith, Idealism, and Realism,” in which he developes more extensively and definitely his principle of faith or immediate knowledge.

2. Jacobi distinguished his faith at the outset from a blind credence in authority. A blind faith is that which supports itself on a foreign view, instead of on the grounds of reason. But this is not the case with his faith, which rather rests upon the innermost necessity of the subject itself. Still farther: his faith is not an arbitrary imagination: we can imagine to ourselves every thing possible, but in order to regard a thing as actual, there must be an inexplicable necessity of our feeling, which we cannot otherwise name than faith. Jacobi was not constant in his terminology, and hence did not always express himself alike in respect of the relation in which faith stood to the different sides of the human faculty of knowledge. In his earlier terminology he placed faith (or as he also called it, the power of faith), on the side of the sense or the receptivity, and let it stand opposed to the understanding and the reason, taking these two terms as equivalent expressions for the finite and immediate knowledge of previous philosophy; afterwards he followed Kant, and, distinguishing between the reason and the understanding, he called that reason which he had previously named sense and faith. According to him now, the faith or intuition of the reason is the organ for perceiving the supersensible. As such, it stands opposed to the understanding. There must be a higher faculty which can learn, in a way inconceivable to sense and the understanding, that which is true in and above the phenomena. Over against the explaining understanding stands the reason, or the natural faith of the reason, which does not explain, but positively reveals and unconditionally decides. As there is an intuition of the sense, so is there a rational intuition through the reason, and a demonstration has no more validity in respect of the latter than in respect of the former. Jacobi justifies his use of the term, intuition of the reason, from the want of any other suitable designation. Language has no other expression to indicate the way in which that, which is unattainable to the sense, becomes apprehended in the transcendental feeling. If any one affirms that he knows any thing, he may properly be required to state the origin of his knowledge, and in doing this, he must of necessity go back either to sensation or to feeling; the latter stands above the former as high as the human species above the brute. So I affirm, then, without hesitation, says Jacobi, that my philosophy starts from pure feeling, and declares the authority of this to be supreme. The faculty of feeling is the highest in man, and that alone which specifically distinguishes him from the brute. This faculty is one and the same with reason; or, reason may be said to find in it its single and only starting point.

Jacobi had the clearest consciousness of the opposition in which he stood, with this principle of immediate knowledge, to previous philosophy. In his introduction to his complete works, he says: “There had arisen since the time of Aristotle an increasing effort in philosophical schools, to subject the immediate knowledge to the mediate, to make that faculty of perception which originally establishes every thing, dependent on the faculty of reflection, which is conditioned through abstraction; to subordinate the archetype to the copy, the essence to the word, the reason to the understanding, and, in fact, to make the former wholly disappear in the latter. Nothing is allowed to be true which is not capable of a double demonstration, in the intuition and in the conception, in the thing and in its image or word; the thing itself, it is said, must truly lie and actually be known only in the word.” But every philosophy which allows only the reflecting reason, must lose itself at length in an utter ignorance. Its end is nihilism.

3. From what has been already said, the position of Jacobi with his principle of faith, in relation to the Kantian philosophy, can, partly at least, be seen. Jacobi had separated himself from this philosophy, partly in the above-named dialogue “David Hume,” (especially in an appendix to this, in which he discussed the transcendental Idealism), and partly in his essay “On the attempt of criticism to bring the reason to the understanding” (1801). His relation to it may be reduced to the following three general points:

(1.) Jacobi does not agree with Kant’s theory of sensuous knowledge. In opposition to this theory he defends the standpoint of empiricism, affirms the truthfulness of the sense-perception, and denies the apriority of space and time, for which Kant contends in order to prove that objects as well as their relations are simply determinations of our own self, and do not at all exist externally to us. For, however much it may be affirmed that there is something corresponding to our notions as their cause, yet does it remain concealed what this something is. According to Kant, the laws of our beholding and thinking are without objective validity, our knowledge has no objective significance. But it is wrong to claim that in the phenomena there is nothing revealed of the hidden truth which lies behind them. With such a claim, it were far better to give up completely the unknown thing-in-itself, and carry out to its results the consequent idealism. “Logically, Kant is at fault, when he presupposes objects which make impressions on our soul. He is bound to teach the strictest idealism.”

(2.) Yet Jacobi essentially agrees with Kant’s critick of the understanding. Jacobi affirmed, as Kant had done, that the understanding is insufficient to know the supersensible, and that the highest ideas of the reason could be apprehended only in faith. Jacobi places Kant’s great merit in having cleared away the ideas, which were simply the products of reflection and logical phantasms. “It is very easy for the understanding, when producing one notion from another, and thus gradually mounting up to ideas, to imagine that, by virtue of these, which, though they carry it beyond the intuitions of the sense, are nothing but logical phantasms, it has not only the faculty but the most decided determination to fly truly above the world of sense, and to gain by its flight a higher science independent of the intuition, a science of the supersensible. Kant discovers and destroys this error and self-deception. Thus there is gained, at least, a clear place for a genuine rationalism. This is Kant’s truly great deed, his immortal merit. But the sound sense of our sage did not allow him to hide from himself that this clear place must disappear in a gulf, which would swallow up in itself all knowledge of the true, unless a God should interpose to hinder it. Here Kant’s doctrine and mine meet.”

(3.) But Jacobi does not fully agree with Kant, in wholly denying to the theoretical reason the faculty of objective knowledge. He blames Kant for complaining that the human reason cannot theoretically prove the reality of its ideas. He affirms that Kant is thus still entangled in the delusion, that the only reason why these ideas cannot be proved, is found in the nature of the ideas themselves, and not in the deficient nature of our knowledge. Kant therefore attempts to seek, in a practical way, a kind of scientific proof; a roundabout way, which, to every profound seeker, must seem folly, since every proof is as impossible as it is unnecessary.

Jacobi agreed better with Kant, than with the post-Kantian philosophy. The atheistic tendency of the latter was especially repulsive to him. “To Kant, that profound thinker and upright philosopher, the words God, freedom, immortality, and religion, signified the same as they have ever done to the sound human understanding; he in no way treats them as nothing but deception. He created offence by irresistibly showing the insufficiency of all proofs of speculative philosophy for these ideas. That which was wanting in the theoretical proof, he made up by the necessary postulates of a pure practical reason. With these, according to Kant’s assurance, philosophy was fully helped out of her difficulty, and the goal, which had been always missed, actually reached. But the first daughter of the critical philosophy (Fichte’s system) makes the living and working moral order itself to be God, a God expressly declared to be without consciousness and self-existence. These frank words, spoken publicly and without restraint, roused some attention, but the fear soon subsided. Presently astonishment ceased wholly, for the second daughter of the critical philosophy (Schelling’s system) gave up entirely the distinction which the first had allowed to remain between natural and moral philosophy, necessity and freedom, and without any further ado affirmed that the only existence is nature, and that there is nothing above; this second daughter is Spinozism transfigured and reversed, an ideal materialism.” This latter allusion to Schelling, connected as it was with other and harder thrusts in the same essay, called out from this philosopher the well-known answer: “Schelling’s Monument to the Treatise on Divine Things, 1812.”

If we now take a critical survey of the philosophical standpoint of Jacobi, we shall find its peculiarity to consist in the abstract separation of understanding and feeling. These two Jacobi could not bring into harmony. “There is light in my heart,” he says, “but it goes out whenever I attempt to bring it into the understanding. Which is the true luminary of these two? That of the understanding, which, though it reveals fixed forms, shows behind them only a baseless gulf? Or that of the heart, which points its light promisingly upwards, though determinate knowledge escapes it? Can the human spirit grasp the truth unless it possesses these two luminaries united in one light? And is this union conceivable except through a miracle?” If now, in order to escape in a certain degree this contradiction between understanding and feeling, Jacobi gave to immediate knowledge the place of mediate as finite knowledge, this was a self-deception. Even that knowledge, which is supposed to be immediate, and which Jacobi regards as the peculiar organ for knowing the supersensible, is also mediate, obliged to go through a course of subjective mediations, and can only give itself out as immediate when it wholly forgets its own origin.