Chapter IX: Kant (1)

The suit between empiricism and rationalism had continued for centuries, but still awaited final decision. Are all our ideas the result of experience, or are they (wholly or in part) an original possession of the mind? Are they received from without (by perception), or produced from within (by self-activity)? Is knowledge a product of sensation or of pure thought? All who had thus far taken part in this discussion had resembled partisans or advocates rather than disinterested judges. They had given less attention to investigation than to the defense of the traditional theses of their schools; they had not endeavored to obtain results, but to establish results already determined; and, along with real arguments, popular appeals had not been despised. Each of the opposing schools had given variations on a definite theme, and whenever timid attempts had been made to bring the two melodies into harmony they had met with no approval. The proceedings thus far had at least made it evident to the unbiased hearer that each of the two parties made extravagant claims, and, in the end, fell into self-contradiction. If the claim of empiricism is true, that all our concepts arise from perception, then not only the science of the suprasensible, which it denies, but also the science of the objects of experience, about which it concerns itself, is impossible. For perception informs us concerning single cases merely, it can never comprehend all cases, it yields no necessary and universal truth; but knowledge which is not apodictically valid for every reasoning being and for all cases is not worthy the name. The very reasons which were intended to prove the possibility of knowledge give a direct inference to its impossibility. The empirical philosophy destroys itself, ending with Hume in skepticism and probabilism. Rationalism is overtaken by a different, and yet an analogous fate--it breaks up into a popular eclecticism. It believes that it has discovered an infallible criterion of truth in the clearness and distinctness of ideas, and a sure example for philosophical method in the method of mathematics. In both points it is wrong. The criterion of truth is insufficient, for Spinoza and Leibnitz built up their opposing theories--the pantheism of the one and the monadology of the other--from equally clear and distinct conceptions; tried by this standard individualism is just as true as pantheism. Mathematics, again, does not owe its unquestioned acceptance and cogent force to the clearness and distinctness of its conceptions, but to the fact that these are capable of construction in intuition. The distinction between mathematics and metaphysics was overlooked, namely, that mathematical thought can transform its conceptions into intuitions, can generate its objects or sensuously present them, which philosophical thought is not in a position to do. The objects of the latter must be given to it, and to the human mind they are given in no other way than through sensuous intuition. Metaphysics seeks to be a science of the real, but it is impossible to conjure being out of thought; reality cannot be proved from concepts, it can only be felt. In making the unperceivable and suprasensible (the real nature of things, the totality of the world, the Deity, and immortality) the special object of philosophy, rationalism looked on the understanding as a faculty of knowledge by which objects are given. In reality objects can never be given through concepts; these only render it possible to think objects given in some other way (by intuition). It is true that concepts of the suprasensible exist, but nothing can be known through them, there is nothing intuitively given to be subsumed under them.

With this failure to perceive the intuitive element in mathematics was joined the mistake of overlooking its synthetic character. The syllogistic method of presentation employed in the Euclidean geometry led to the belief that the more special theorems had been derived from the simpler ones, and these from the axioms, by a process of conceptual analysis; while the fact is that in mathematics all progress is by intuition alone, the syllogism serving merely to formulate and explain truths already attained, but not to supply new ones. Following the example of mathematics thus misunderstood, the mission of philosophy was made to consist in the development of the truths slumbering in pregnant first principles by means of logical analysis. If only there were metaphysical axioms! If we only did not demand, and were not compelled to demand, of true science that it increase our knowledge, and not merely give an analytical explanation of knowledge. When once the clearness and distinctness of conceptions had been taken in so purely formal a sense, it was inevitable that in the end, as productivity became less, the principle should be weakened down to a mere demand for the explanation and elucidation of the metaphysical ideas present in popular consciousness. Thus the rationalistic current lost itself in the shallow waters of the Illumination, which soon gave as ready a welcome to the empirical theories--since these also were able to legitimate themselves by clear and distinct conceptions--as it had given to the results of the rationalistic systems.

It was thus easy to see that each of the contending parties had been guilty of one-sidedness, and that in order to escape this a certain mean must be assumed between the two extremes; but it was a much more difficult matter to discover the due middle ground. Neither of the opposing standpoints is so correct as its defenders believe, and neither so false as its opponents maintain. Where, then, on either side, does the mistaken narrowness begin, and how far does the justification of each extend?

The conflict centers, first, about the question concerning the origin of human knowledge and the sphere of its validity. Rationalism is justified when it asserts that some ideas do not come from the senses. If knowledge is to be possible, some concepts cannot originate in perception, those, namely, by which knowledge is constituted, for if they should, it would lack universality and necessity. The sole organ of universally valid knowledge is reason. Empiricism, on the other hand, is justified when it asserts that the experiential alone is knowable. Whatever is to be knowable must be given as a real in sensuous intuition. The only organ of reality is sensibility. Rationalism judges correctly concerning the origin of the most important classes of ideas; empiricism concerning the sphere of their validity. The two may be thus combined: some concepts (those which produce knowledge) take their origin in reason or are _a priori_, but they are valid for objects of experience alone. The conflict concerns, secondly, the use of the deductive (syllogistic) or the inductive method. Empiricism, through its founder Bacon, had recommended induction in place of the barren syllogistic method, as the only method which would lead to new discoveries. It demands, above all things, the extension of knowledge. Rationalism, on the contrary, held fast to the deductive method, because the syllogism alone, in its view, furnishes knowledge valid for all rational beings. It demands, first of all, universality and necessity in knowledge. Induction has the advantage of increasing knowledge, but it leads only to empirical and comparative, not to strict universality. The syllogism has the advantage of yielding universal and necessary truth, but it can only explicate and establish knowledge, not increase it. May it not be possible so to do justice to the demands of both that the advantages which they seek shall be combined, and the disadvantages which have been feared, avoided? Are there not cognitions which increase our knowledge (are _synthetic_) without being empirical, which are universally and necessarily valid (_a priori_) without being analytic? From these considerations arises the main question of the _Critique of Pure Reason_: How are synthetic judgments _a priori_ possible?

The philosophy of experience had overestimated sense and underestimated the understanding, when it found the source of all knowledge in the faculty of perception and degraded the faculty of thought to an almost wholly inactive recipient of messages coming to it from without. From the standpoint of empiricism concepts (Ideas) deserve confidence only in so far as they can legitimate themselves by their origin in sensations (impressions). It overlooks the _active_ character of all knowing. Among the rationalists, on the other hand, we find an underestimation of the senses and an overestimation of the understanding. They believe that sense reveals only the deceptive exterior of things, while reason gives their true non-sensuous essence. That which the mind perceives of things is deceptive, but that which it thinks concerning them is true. The former power is the faculty of confused, the latter the faculty of distinct knowledge. Sense is the enemy rather than the servant of true knowledge, which consists in the development and explication of pregnant innate conceptions and principles. These philosophers forget that we can never reach reality by conceptual analysis; and that the senses have a far greater importance for knowledge than merely to give it an impulse; that it is they which supply the understanding with real objects, and so with the content of knowledge. Beside the (formal) activity (of the understanding), cognition implies a passive factor, a reception of impressions. Neither sense alone nor the understanding alone produces knowledge, but both cognitive powers are necessary, the active and the passive, the conceptual and the intuitive. Here the question arises, How do concept and intuition, sensuous and rational knowledge, differ, and what is the basis of their congruence? Notwithstanding their different points of departure and their variant results, the two main tendencies of modern philosophy agree in certain points. If the conflict between the two schools and their one-sidedness suggested the idea of supplementing the conclusions of the one by those of the other, the recognition of the incorrectness of their common convictions furnished the occasion to go beyond them and to establish a new, a higher point of view above them both, as also above the eclecticism which sought to unite the opposing principles. The errors common to both concern, in the first place, the nature of judgment and the difference between sensibility and understanding. Neither side had recognized that the peculiar character of judgment consists in _active connection_. The rationalists made judgment an active function, it is true, but a mere activity of conscious development, of elucidation and analytical inference, which does not advance knowledge a single step. The empiricists described it as a process of comparison and discrimination, as the mere perception and recognition of the relations and connections already existing between ideas; while in reality judgment does not discover the relations and connections of representations, but itself establishes them. In the former case the synthetic moment is ignored, in the latter the active moment. The imperfect view of judgment was one of the reasons for the appearance of extreme theories concerning the origin of ideas in reason or in perception. Rationalism regards even those concepts which have a content as innate, whereas it is only formal concepts which are so. Empiricism regards all, even the highest formal concepts (the categories), as abstracted from experience, whereas experience furnishes only the content of knowledge, and not the synthesis which is necessary to it. On the one hand too much, and on the other too little, is regarded as the original possession of the understanding. The question "What concepts are innate?" can be decided only by answering the further question, What are the concepts through which the faculty of judgment connects the representations obtained from experience? These connective concepts, these formal instruments of synthesis are _a priori_. The agreement of the two schools is still greater in regard to the relation of sense and understanding, notwithstanding the apparently sharp contrast between them. The empiricist considers thought transformed, sublimated perception, while the rationalist sees in perception only confused and less distinct thought. For the former concepts are faded images of sensations, for the latter sensations are concepts which have not yet become clear; the difference is scarcely greater than if the one should call ice frozen water, and the other should prefer to call water melted ice. Both arrange intuition and thought in a single series, and derive the one from the other by enhancement or attenuation. Both make the mistake of recognizing only a difference in degree where a difference in kind exists. In such a case only an energetic dualism can afford help. Sense and understanding are not one and the same cognitive power at different stages, but two heterogeneous faculties. Sensation and thought are not different in degree, but in kind. As Descartes began with the metaphysical dualism of extension and thought, so Kant begins with the noëtical dualism of intuition and thought.

Much more serious, however, than any of the mistakes yet mentioned was a sin of omission of which the two schools were alike guilty, and the recognition and avoidance of which constituted in Kant's own eyes the distinctive character of his philosophy and its principiant-advance beyond preceding systems. The pre-Kantian thinker had proceeded to the discussion of knowledge without raising _the question of the possibility of knowledge_. He had approached things in the full confidence that the human mind was capable of cognizing them, and with a naïve trust in the power of reason to possess itself of the truth. His trust was naïve and ingenuous, because the idea that it could deceive him had never entered his mind. Now no matter whether this belief in man's capacity for knowledge and in the possibility of knowing things is justifiable or not, and no matter how far it may be justifiable, it was in any case untested; so that when the skeptic approached with his objections the dogmatist was defenseless. All previous philosophy, so far as it had not been skeptical, had been, according to Kant's expression, dogmatic; that is, it had held as an article of faith, and without precedent inquiry, that we possess the power of cognizing objects. It had not asked _how_ this is possible; it had not even asked what knowledge is, what may and must be demanded of it, and by what means our reason is in a position to satisfy such demands. It had left human intelligence and its extent uninvestigated. The skeptic, on the other hand, had been no more thorough. He had doubted and denied man's capacity for knowledge just as uncritically as the dogmatist had believed and presupposed it. He had directed his ingenuity against the theories of dogmatic philosophy, instead of toward the fundamental question of the possibility of knowledge. Human intelligence, which the dogmatist had approached with unreasoned trust and the skeptic with just as unreasoned distrust, is subjected, according to the plan of the critical philosopher, to a searching examination. For this reason Kant termed his standpoint "criticism," and his undertaking a "Critique of Reason." Instead of asserting and denying, he investigates how knowledge arises, of what factors it is composed, and how far it extends. He inquires into the origin and extent of knowledge, into its sources and its limits, into the grounds of its existence and of its legitimacy. The Critique of Reason finds itself confronted by two problems, the second of which cannot be solved until after the solution of the first. The investigation of the sources of knowledge must precede the inquiry into the extent of knowledge. Only after the conditions of knowledge have been established can it be ascertained what objects are attainable by it. Its sphere cannot be determined except from its origin.

Whether the critical philosopher stands nearer to the skeptic or to the dogmatist is rather an idle question. He is specifically distinct from both, in that he summons and guides the reason to self-contemplation, to a methodical examination of its capacity for knowledge. Where the one had blindly trusted and the other suspected and denied, he investigates; they overlook, he raises the question of the possibility of knowledge. The critical problem does not mean, Does a faculty of knowledge exist? but, Of what powers is it composed? are all objects knowable which have been so regarded? Kant does not ask whether, but how and by what means, knowledge is possible. Everyone who gives himself to scientific reflection must postulate that knowledge is possible, and the demand of the noëtical theorists of the day for a philosophy absolutely without assumptions is quite incapable of fulfillment. Nay, in order to be able to begin his inquiry at all, it was necessary for Kant to assume still more special postulates; for that a cognition of cognition is possible, that there is a critical, self-investigating reason could, at first, be only a matter of belief. This would not have excluded a supplementary detailed statement concerning the _how_ of this self-knowledge, concerning the organ of the critical philosophy. But Kant never gave one, and the omission subsequently led to a sharp debate concerning the character and method of the Critique of Reason. On this point, if we may so express it, Kant remained a dogmatist.

Kant felt himself to be the finisher of skepticism; but this was chiefly because he had received the strongest impulse to the development of his critique of knowledge from Hume's inquiries concerning causation. Brought up in the dogmatic rationalism of the Wolffian school, to which he remained true for a considerable period as a teacher and writer (till about 1760), although at the same time he was inquiring with an independent spirit, Kant was gradually won over through the influence of the English philosophy to the side of empirical skepticism. Then--as the result, no doubt, of reading the _Nouveaux Essais_ of Leibnitz, published in 1765--he returned to rationalistic principles, until finally, after a renewal of empirical influences,[1] he took the position crystallized in the _Critique of Pure Reason_, 1781, which, however, experienced still other, though less considerable, changes in the sequel, just as in itself it shows the traces of previous transformations.

[Footnote 1: Cf. H. Vaihinger's _Kommentar zu Kants Kritik der reinen Vernunft_, vol. i., 1881, pp. 48-49. This is a work marked by acuteness, great industry, and an objective point of view which merits respect. The second volume, which treats of the Transcendental Aesthetic, appeared in 1892.]

It would be a most interesting task to trace in the writings which belong to Kant's pre-critical period the growth and development of the fundamental critical positions. Here, however, we can only mention in passing the subjects of his reflection and some of the most striking anticipations and beginnings of his epoch-making position. Even his maiden work, _Thoughts on the True Estimation of Vis Viva_, 1747, betokens the mediating nature of its author. In this it is argued that when men of profound and penetrating minds maintain exactly opposite opinions, attention must be chiefly directed to some intermediate principle to a certain degree compatible with the correctness of both parties. The question under discussion was whether the measure of _vis viva_ is equal, as the Cartesians thought, to the product of the mass into the velocity, or, according to the Leibnitzians, to the product of the mass into the square of the velocity. Kant's unsatisfactory solution of the problem--the law of Descartes holds for dead, and that of Leibnitz for living forces--drew upon him the derision of Lessing, who said that he had endeavored to estimate living forces without having tested his own. A similar tendency toward compromise--this time it is a synthesis of Leibnitz and Newton--is seen in his _Habilitationsschrift, Principiorum Primorum Cognitionis Metaphysicae Nova Dilucidatio_, 1755, and in the dissertation _Monadologia Physica_, 1756. The former distinguishes between _ratio essendi_ and _ratio cognoscendi_, rejects the ontological argument, and defends determinism against Crusius on Leibnitzian grounds. In the _Physical Monadology_ Kant gives his adherence to dynamism (matter the product of attraction and repulsion), and makes the monads or elements of body fill space without prejudice to their simplicity. A series of treatises is devoted to subjects in natural science: The Effect of the Tides in retarding the Earth's Rotation; The Obsolescence of the Earth; Fire (Inaugural Dissertation), Earthquakes, and the Theory of the Winds. The most important of these, the _General Natural History and Theory of the Heavens_, 1755, which for a long time remained unnoticed, and which was dedicated to Frederick II., developed the hypothesis (carried out forty years later by Laplace in ignorance of Kant's work) of the mechanical origin of the universe and of the motion of the planets. It presupposes merely the two forces of matter, attraction and repulsion, and its primitive chaotic condition, a world-mist with elements of different density. It is noticeable that Kant acknowledges the failure of the mechanical theory at two points: it is brought to a halt at the origin of the organic world and at the origin of matter. The mechanical cosmogony is far from denying creation; on the contrary, the proof that this well-ordered and purposive world necessarily arose from the regular action of material forces under law and without divine intervention, can only serve to support our assumption of a Supreme Intelligence as the author of matter and its laws; the belief is necessary, just because nature, even in its chaotic condition, can act only in an orderly and regular way.

The empirical phase of Kant's development is represented by the writings of the 60's. _The False Subtlety of the Four Syllogistic Figures_, 1762, asserts that the first figure is the only natural one, and that the others are superfluous and need reduction to the first. In the _Only Possible Foundation for a Demonstration of the Existence of God_, 1763, which, in the seventh Reflection of the Second Division, recapitulates the cosmogony advanced in the _Natural History of the Heavens_, the discussions concerning being ("existence" is absolute position, not a predicate which increases the sum of the qualities but is posited in a merely relative way), and the conclusion, prophetical of his later point of view, "It is altogether necessary that we should be _convinced_ of the existence of God, but not so necessary that his existence should be _demonstrated_" are more noteworthy than the argument itself. This runs: All possibility presupposes something actual wherein and whereby all that is conceivable is given as a determination or a consequence. That actuality the destruction of which would destroy all possibility is absolutely necessary. Therefore there exists an absolutely necessary Being as the ultimate real ground of all possibility; this Being is one, simple, unchangeable, eternal, the _ens realissimum_ and a spirit. The _Attempt to introduce the Notion of Negative Quantities into Philosophy_, 1763, distinguishes--contrary to Crusius--between logical opposition, contradiction or mere negation (_a_ and _not-a_, pleasure and the absence of pleasure, power and lack of power), and real opposition, which cannot be explained by logic (+_a_ and -_a_, pleasure and pain, capital and debts, attraction and repulsion; in real opposition both determinations are positive, but in opposite directions). Parallel with this it distinguishes, also, between logical ground and real ground. The prize essay, _Inquiry concerning the Clearness_ (Evidence) _of the Principles of Natural Theology and Ethics_, 1764, draws a sharp distinction between mathematical and metaphysical knowledge, and warns philosophy against the hurtful imitation of the geometrical method, in place of which it should rather take as an example the method which Newton introduced into natural science. Quantity constitutes the object of mathematics, qualities, the object of philosophy; the former is easy and simple, the latter difficult and complicated--how much more comprehensible the conception of a trillion is than the philosophical idea of freedom, which the philosophers thus far have been unable to make intelligible. In mathematics the general is considered under symbols _in concrete_, in philosophy, by means of symbols _in abstracto_; the former constructs its object in sensuous intuition, while the object of the latter is given to it, and that as a confused concept to be decomposed. Mathematics, therefore, may well begin with definitions, since the conception which is to be explained is first brought into being through the definition, while philosophy must begin by seeking her conceptions. In the former the definition is first in order, and in the latter almost always last; in the one case the method is synthetic, in the other it is analytic. It is the function of mathematics to connect and compare clear and certain concepts of quantity in order to draw conclusions from them; the function of philosophy is to analyze concepts given in a confused state, and to make them detailed and definite. Philosophy has also this disadvantage, that it possesses very many undecomposable concepts and undemonstrable propositions, while mathematics has only a few such. "Philosophical truths are like meteors, whose brightness gives no assurance of their permanence. They vanish, but mathematics remains. Metaphysics is without doubt the most difficult of all human sciences _(Einsichten)_, but a metaphysic has never yet been written"; for one cannot be so kind as to "apply the term philosophy to all that is contained in the books which bear this title." In the closing paragraphs, on the ultimate bases of ethics, the stern features of the categorical imperative are already seen, veiled by the English theory of moral sense, while the attractive _Observations on the Feeling of the Beautiful and the Sublime_, which appeared in the same year, still naïvely follow the empirical road.

The empirical phase reaches its skeptical termination in the satire _Dreams of a Ghost-seer explained by the Dreams of Metaphysics_, 1766, which pours out its ingenious sarcasm impartially on spiritualism and on the assumed knowledge of the suprasensible. Here Kant is already clearly conscious of his new problem, a theory of the limits of human reason, conscious also that the attack on this problem is to be begun by a discussion of the question of space. This second question had been for many years a frequent subject of his reflections;[1] and it was this part of the general critical problem that first received definitive solution. In the Latin dissertation _On the Form and Principles of the Sensible and Intelligible World_, 1770, which concludes the pre-critical period, and which was written on the occasion of his assumption of his chair as ordinary professor, the critique of sensibility, the new theory of space and time, is set forth in approximately the same form as in the _Critique of Pure Reason_, while the critique of the understanding and of reason, the theory of the categories and the Ideas and of the sphere of their validity, required for its completion the intellectual labor of several more years. For this essay, _De Mundi Sensibilis atque Intelligibilis Forma et Principiis_, leaves unchallenged the possibility of a knowledge of things in themselves and of God, thus showing that its author has abandoned the skepticism maintained in the _Dreams of a Ghost-seer_, and has turned anew to dogmatic rationalism, whose final overthrow required another swing in the direction of skeptical empiricism. In regard to the progress of this latter phase of opinion, the letters to M. Herz are almost the only, though not very valuable, source of information.

[Footnote 1: _New Theory of Motion and Rest_, 1758; _On the First Ground of the Distinction of Positions in Space_, 1768; besides several of the works mentioned above.]

The _Critique of Pure Reason_ appeared in 1781, much later than Kant had hoped when he began a work on "The Limits of Sensibility and Reason," and a second, altered edition in 1787.[1] After the _Prolegomena to every Future Metaphysic which may present itself as Science_, 1783, had given a popular form to the critical doctrine of knowledge, it was followed by the critical philosophy of ethics in the _Foundation of the Metaphysics of Ethics_, 1785, and the _Critique of Practical Reason_, 1788; by the critical aesthetics and teleology in the _Critique of Judgment_, 1790; and by the critical philosophy of religion in _Religion within the Limits of Reason Only_, 1793[2] (consisting of four essays, of which the first, "Of Radical Evil," had already appeared in the _Berliner Monatsschrift_ in 1792). The _Metaphysical Elements of Natural Science_, 1786, and the _Metaphysics of Ethics_, 1797 (in two parts, "Metaphysical Elements of the Theory of Right," and "Metaphysical Elements of the Theory of Virtue "), are devoted to the development of the system. The year 1798 brought two more larger works, the _Conflict of the Faculties_ and the _Anthropology_. Of the reviews, that on Herder's _Ideen_ maybe mentioned, and among the minor essays, the following: _Idea for a Universal History in a Cosmopolitan Sense, Answer to the Question: What is Illumination f_ both in 1784; _What does it mean to Orient oneself in Thought_? 1786; _On the Use of Teleological Principles in Philosophy_, 1788; _On a Discovery according to which all Recent Criticism of Pure Reason is to be superseded by a Previous One_, 1790; _On the Progress of Metaphysics since the Time of Wolff; On Philosophy in General, The End of all Things_, 1794; _On Everlasting Peace_, 1795. Kant's _Logic_ was published by Jäsche in 1800; his _Physical Geography_ and his _Observations on Pedagogics_ by F.T. Rink in 1803; his lectures on the _Philosophical Theory of Religion_ (1817; 2d. ed., 1830) and on _Metaphysics_ (1821; cf. Benno Erdmann in the _Philosophische Monatshefte_, vol. xix. 1883, p. 129 _seq_., and vol. xx. 1884, p. 65 _seq_.) by Pölitz. If we may judge by the specimens given by Reicke in the _Altpreussische Monatsschrift_, 1882-84, and by Krause himself,[3] the promised publication of a manuscript of Kant's last years, now in possession of the Hamburg pastor, Albrecht Krause, and which discusses the transition from the metaphysical elements of natural science to physics, will hardly meet the expectations which some have cherished concerning it. Benno Erdmann has issued _Nachträge zu Kants Kritik der reinen Vernunft aus Kants Nachlass_, 1881, and _Reflexionen Kants zur kritischen Philosophie aus handschriftlichen Aufzeichnungen_--the first volume first _Heft (Reflexionen zur Anthropologie_) appearing in 1882, the second volume _(Reflexionen zur Kritik der reinen Vernunft, aus Kants Handexemplar von Baumgartens Metaphysica)_ in 1884. Max Müller has made an English translation of the _Critique of Pure Reason_, 2 vols., 1881.[4]

[Footnote 1: There has been much discussion and much has been written concerning the relation of the two editions. In opposition to Schopenhauer and Kuno Fischer it must be maintained that the alterations in the second edition consist in giving greater prominence to realistic elements, which in the first edition remained in the background, though present even there.]

[Footnote 2: This publication was the occasion of a conflict between Kant and the censorship concerning the right of free religious inquiry; cf. Dilthey in the _Archiv für Geschichte der Philosophie_, vol. in. 1890, pp. 418-450.]

[Footnote 3: A. Krause: _I. Kant wider K. Fischer, zum ersten Male mit Hülfe des verloren gewesenen Kantischen Hauptwerkes vertheidigt_, 1884 (in reply, K. Fischer, _Das Streber- und Gründerthum in der Litteratur_, 1884); also, _Das nachgelassene Werk I. Kants, mit Belegen populär-wissenschaftlich dargestellt_, 1888.]

[Footnote 4: Besides this (centenary) translation the English reader may be referred to the earlier version of Meiklejohn in Bonn's Library; to the versions of the _Prolegomena_ by Bax (also in Bonn's Library, and including the _Metaphysical Elements of Natural Science_), and Mahaffy and Bernard, new ed., 1889; to Abbot's _Kant's Theory of Ethics_, 4th ed., 1889, containing the _Foundation of the Metaphysics of Ethics_ and the _Critique of Practical Reason_ entire, with portions of the _Metaphysics of Ethics_ and _Religion within the Limits of Reason Only_; to Bernard's translation of the _Kritik of Judgment_, 1892; and to Watson's _Selections from Kant_, 2d ed., 1888 (in Sneath's Modern Philosophers, 1892).--TR.]

The best complete edition of the works of Kant is the second edition of Hartenstein, in eight volumes, 1867-68, which is chronologically arranged and excellently gotten up. Simultaneously with the first edition of Hartenstein in ten volumes, in 1838 _seq_., appeared the edition in twelve volumes by K. Rosenkranz and F.W. Schubert (containing in the last volumes a biography of Kant by Schubert, and a history of the Kantian philosophy by Rosenkranz, 1842). Kehrbach's edition of the principal works in Reclam's _Universal-Bibliothek_, with the pagination of the original and collective editions (1877 _seq_.), is more valuable than Von Kirchmann's edition of the complete works in his _Philosophische Bibliothek_.

Among the works on Kant those of Kuno Fischer (vols. iii.-iv. of the _Geschichte der neueren Philosophie_, 3d ed., 1882; also Kant's _Leben und die Grundlagen seiner Lehre_, 1860) take the first place. The writings of Liebmann, Cohen, Stadler, Riehl, Volkelt, and others will be mentioned later, in connection with the neo-Kantian movement; here we may give some of the more important monographs and essays, selected from the enormously developed Kantian literature:

Ad. Böhringer, _Kants erkenntnisstheoretischer Idealismus_, 1888; K. Dieterich, _Die Kantische Philosophie in ihrer inneren Entwickelungsgeschichte_, 2 parts, 1885 (first published separately, _Kant und Newton_, 1877; _Kant und Rousseau_, 1878); W. Dilthey, _Aus den Rostocker Kanthandschriften_ in the _Archiv für Geschichte der Philosophie_, vols. ii.-iii. 1889-90; M.W. Drobisch, _Kants Ding an sich und sein Erfahrungsbegriff_, 1885; B. Erdmann, _Kants Kritizismus in der I. und II. Auflage der Kritik der reinen Vernunft_, 1878; the same, _Kants Prolegomena herausgegeben und erläutert_, 1878, Introduction (in reply Emil Arnoldt, _Kants Prolegomena nicht doppelt redigiert_, 1879; cf. also H. Vaihinger, _Die Erdmann-Arnoldtsche Kontroverse_ in the _Philosophische Monatshefte_, vol. xvi. 1880); Franz Erhardt, _Kritik der Kantischen Antinomienlehre_, 1888; R. Eucken, _Ueber Bilder und Gleichnisse bei Kant, Zeitschrift für Philosophie_, vol. lxxxiii, 1883, reprinted in his _Beiträge zur Geschichte der neueren Philosophie_, 1886; F. Frederichs, _Der phänomenale Idealismus Berkeleys und Kants_, 1871; the same, _Kants Prinzip der Ethik_, 1879; Ed. von Hartmann, _Das Ding an sich und seine Beschaffenheit_, 1871, in the 2d ed., 1875, and the 3d, 1885, entitled _Kritische Grundlegung des transzendentalen Realismus_; C. Hebler, _Kantiana_, in his _Philosophische Aufsätze_, 1869; Alfred Hegler, _Die Psychologie in Kants Ethik_, 1891; A. Hölder, _Darstellung der Kantischen Erkenntnisstheorie_, 1873 J. Jacobson, _Die Auffindung des Apriori_, 1876; the same, _Ueber die Beziehungen zwischen Kategorien und Urtheilsformen_, 1877; Wilhelm Koppelmann, _Kants Lehre vom analytischen Urtheil, Philosoph. Monatshefte_, vol. xxi, 1885; the same, _Lotzes Stellung zu Kants Kritizismus, Zeitschrift für Philosophie_, vol. lxxxviii, 1886; the same, _Kants Lehre vom kategorischen Imperativ_, 1888; the same, _Kant und die Grundlagen der Christlichen Religion_, 1890; E. Laas, _Kants Analogien der Erfahrung_, 1876; the same, _Einige Bemerkungen zur Transzendentalphilosophie_, Strassburg _Abhandlungen_, 1884; J. Mainzer, _Die kritische Epoche in der Lehre von der Einbildungskraft_, 1881; J.B. Meyer, _Kants Psychologie_, 1870; F. Paulsen, _Was Kant uns sein kann, Vierteljahrsschrift für wissenschaftliche Philosophie_, 1881; B. Pünjer, _Die Religionslehre Kants_, 1874; R. Quaebicker, _Kants und Herbarts metaphysische Grundansichten über das Wesen der Seele_, 1870; J. Rehmke, _Physiologie und Kantianismus_, address in Eisenach, 1883; Rud. Reicke, _Lose Blätter aus Kants Nachlass_, 1889 (on this H. Vaihinger in the _Zeitschrift für Philosophie_, vol. xcvi. 1889); O. Riedel, _Die monadologischen Bestimmungen in Kants Lehre vom Ding an sich_, dissertation at Kiel, 1884; O. Schneider, _Die psychologische Entwickelung des Apriori_, 1883; the same, _Transzendentalpsychologie_, 1891; F. Staudinger, _Noumena_, 1884; M. Steckelmacher, _Die formale Logik Kants_, Breslau Prize Essay, 1879; A. Stern, _Die Beziehung Garves zu Kant, nebst ungedruckten Briefen_, 1884; C. Stumpf, _Psychologie und Erkenntnisstheorie, Abhandlungen der bayerischen Akademie der Wissenschaften_, 1891; G. Thiele, _Kants intellectuelle Anschauung als Grundbegriff seines Kritizismus_, 1876; the same, _Die Philosophie Kants nach ihrem systematischen Zusammenhange und ihrer logischhistorischen Entiwickelung_, I. (1) _Kants vorkritische Naturphilosophie_, 1882; (2) _Kants vorkritische Erkenntnisstheorie_, 1887; Ad. Trendelenburg, _Ueber eine Lücke in Kants Beweis von der ausschliessenden Subjectivität des Raumes and der Zeit_ in vol. iii. of his _Historische Beiträge zur Philosophie_, 1867; Ueberhorst, _Kants Lehre von dem Verhältnisse der Kategorien zu der Erfahrung_, 1878; H. Vaihinger, _Eine Blattversetzung in Kants Prolegomena, Philosoph. Monatshefte_, vol. xv. 1879; the same, _Zu Kants Widerlegung des Idealismus_, Strassburg _Abhandlungen_, 1884; J. Walter, _Zum Gedächtniss Kants, Festrede_, 1881; Th. Weber, _Zur Kritik der Kantischen Erkenntnisstheorie_ (from the _Zeitschrift für Philosophie_), 1882; W. Windelband, _Ueber die verschiedenen Phasen der Kantischen Lehre vom Ding an sich, Vierteljahrsschrift für wissenschaftliche Philosophie_, 1877 (cf. the same author's _Geschichte der neueren Philosophie_, § 58); J. Witte, _Beiträge zum Verständniss Kants_, 1874; the same, _Kantischer Kritizismus gegenüber unkritischem Dilettantismus_ (against A. Stöhr), 1885; Wohlrabe, _Kants Lehre vom Gewissen_, 1889; E. Zeller, _Ueber das Kantische Moralprinzip_, 1880; R. Zimmermann, _Ueber Kants Widerlegung des Idealismus von Berkeley_, 1871; the same, _Ueber Kants mathematisches Vorurtheil und dessen Folgen_, 1871.

Popular expositions have been given by the following: K. Fortlage (in his _Philos. Vorträge_, 1869); E. Last, _Mehr Licht! Die Haupsätze Kants und Schopenhauers_, 1879; the same, _Die realistiche und die idealistische Anschauung entwickelt an Kants Idealität von Raum und Zeit_, 1884; H. Romundt, _Antaeus, neuer Aufbau der Lehre Kants über Seele, Freiheit, und Gott_, 1882; the same, _Grundlegung zur Reform der Philosophie, vereinfachte und erweiterte Darstellung von Kants Kritik der reinen Vernunft_, 1885; the same, _Die Vollendung des Socrates, Kants Grundlegung zur Reform der Sittenlehre_; the same, _Ein neuer Paulus, Kants Grundlegung zu einer sicheren Lehre von der Religion_, 1886; the same, _Die drei Fragen Kants_, 1887; A. Krause, _Populäre Darstellung von Kants Kritik der reinen Vernunft_, 1881; K. Lasswitz, _Die Lehre Kants von der Idealität des Raumes und der Zeit_, 1883; Wilhelm Münz, _Die Grundlagen der Kantischen Erkenntnisstheorie_, 2d ed., 1885.

Among foreigners Villers, Cousin, Nolen, Desdouits, Cantoni, E. Caird [_\A Critical Account of the Philosophy of Kant_, 1877; _The Critical Philosophy of Immanuel Kant_, 2 vols., 1889], Adamson _[On the Philosophy of Kant_, 1879, and a valuable article in the _Encyclopedia Britannica_, 9th ed., vol. xiii.], Stirling [_Text-book to Kant_, 1881], [Watson, _Kant and his English Critics_, 1881], Morris _Kant's Critique of Pure Reason_, Griggs's Philosophical Classics, 1882, [Wallace, _Kant_, Blackwood's Philosophical Classics, 1882; Porter, _Kant's Ethics_, Griggs's Philosophical Classics, 1886; Green, _Lectures_, Works, vol. ii., 1886.--Tr.], have among others made contributions to Kantian literature. Of the older works we may mention the dictionaries of E. Schmid, 1788, and Mellin (in six volumes), 1797 _seq_., the critique of the Kantian philosophy in the first volume of Schopenhauer's chief work, 1819, and the essay of C.H. Weisse, _In welchem Sinne hat sich die deutsche Philosophie jetzt wieder an Kant zu orientieren_, 1847.

Kant's outward life was less eventful and less changeful than his philosophical development.[1] Born in Königsberg in 1724, the son of J.G. Cant, a saddler of Scottish descent, his home and school training were both strict and of a markedly religious type. He was educated at the university of his native city, and for nine years, from 1746 on, filled the place of a private tutor. In 1755 he became _Docent_, in 1770 ordinary professor in Königsberg, serving also for six years of this time as under-librarian. He seldom left his native city and never the province. The clearness which marked his extremely popular lectures on physical geography and anthropology was due to his diligent study of works of travel, and to an unusually acute gift of observation, which enabled him to draw from his surroundings a comprehensive knowledge of the world and of man. He ceased lecturing in 1797, and in 1804 old age ended a life which had always, even in minute detail, been governed by rule. A man of extreme devotion to duty, particularity, and love of truth, and an amiable, bright, and witty companion, Kant belongs to the acute rather than to the profound thinkers. Among his manifold endowments the tendency to combination and the faculty of intuition (as the _Critique of Judgment_ especially shows) are present to a noticeable degree, yet not so markedly as the power of strict analysis and subtle discrimination. So that, although a mediating tendency is rightly regarded as the distinguishing characteristic of the Kantian thinking, it must also be remembered that synthesis is everywhere preceded by a mighty work of analysis, and that this still exerts its power even after the adjustment is complete. Thus Kant became the energetic defender of a qualitative view of the world in opposition to the quantitative view of Leibnitz, for which antitheses (_e.g._, sensation and thought, feeling and cognition, good and evil, duty and inclination) fade into mere differences of degree.

[Footnote 1: The following have done especially valuable service in the investigation of the development of Kant's doctrine: Paulsen (_Versuch einer Entwickelungsgeschichte der Kantischen Erkenntnisstheorie_, 1875), B. Erdmann, Vaihinger, and Windelband. Besides Hume and Leibnitz, Newton, Locke, Shaftesbury, Rousseau, and Wolff exercised an important influence on Kant.]

In the beginning of this chapter we have indicated how the new ideal of knowledge, under whose banner Kant brought about a reform of philosophy, grew out of the conflict between the rationalistic (dogmatic) and the empirical (skeptical) systems. This combines the Baconian ideal of the extension of knowledge with the Cartesian ideal of certainty in knowledge. It is synthetic judgments alone which extend knowledge, while analytic judgments are explicative merely.[1] _A priori_ judgments alone are perfectly certain, absolutely universal, and necessarily valid; while _a posteriori_ judgments are subjectively valid merely, lack necessity, and, at best, yield only relative universality.[2] All analytic judgments are _a priori_, all empirical or _a posteriori_ judgments are synthetic. Between the two lies the object of Kant's search. Do _synthetic judgments a priori_ exist, and how are they possible?

[Footnote 1: "All bodies are extended" is an analytic judgment; "all bodies possess weight," a synthetic judgment. The former explicates the concept of the subject by bringing into notice an idea already contained in it and belonging to the definition as a part thereof; it is based on the law of contradiction: an unextended body is a self-contradictory concept. The latter, on the contrary, goes beyond the concept of the subject and adds a predicate which had not been thought therein. It is experience which teaches us that weight is joined to matter, a fact which cannot be derived from the concept of matter. Almost all mathematical principles are synthetic, and here, as will be shown, it is not experience but "pure intuition" which permits us to go beyond the concept and add a new mark to it.]

[Footnote 2: The Scholastics applied the term _a priori_ to knowledge from causes (from that which precedes), and _a posteriori_ to knowledge from effects. Kant, following Leibnitz and Lambert, uses the terms to designate the antithesis, knowledge from reason and knowledge from experience. An _a priori_ judgment is a judgment obtained without the aid of experience. When the principle from which it is derived is also independent of experience it is absolutely _a priori_, otherwise it is relatively _a priori_.]

Two sciences discuss the _how_, and a third the _if_ of such judgments, which, at the same time, are ampliative and absolutely universal and necessary. The first two sciences are pure mathematics and pure natural science, of which the former is protected against doubt concerning its legitimacy by its evident character, and the latter, by the constant possibility of verification in experience; each, moreover, can point to the continuous course of its development. All this is absent in the third science, metaphysics, as science of the suprasensible, and to its great disadvantage. Experiential verification is in the nature of things denied to a presumptive knowledge of that which is beyond experience; it lacks evidence to such an extent that there is scarcely a principle to be found to which all metaphysicians assent, much less a metaphysical text-book to compare with Euclid; there is so little continuous advance that it is rather true that the later comers are likely to overthrow all that their predecessors have taught. In metaphysics, therefore, which, it must be confessed, is actual as a natural tendency, the question is not, as in the other two sciences, concerning the grounds of its legitimacy, but concerning this legitimacy itself. Mathematics and pure physics form synthetic judgments _a priori_, and metaphysics does the same. But the principles of the two former are unchallenged, while those of the third are not. In the former case the subject for investigation is, Whence this authority? in the latter case, Is she thus authorized?

Thus the main question, How are synthetic judgments _a priori_ possible? divides into the subordinate questions, How is pure mathematics possible? How is pure natural science possible, and, How is metaphysics (in two senses: metaphysics in general, and metaphysics as science) possible? The Transcendental _Aesthetic_ (the critique of sensibility or the faculty of intuition) answers the first of these questions; the Transcendental _Analytic_ (the critique of the understanding), the second; and the Transcendental _Dialectic_ (the critique of "reason" in the narrower sense) and the Transcendental _Doctrine of Method (Methodenlehre)_, the third. The Analytic and the Dialectic are the two parts of the Transcendental "Logic" (critique of the faculty of thought), which, together with the Aesthetic, forms the Transcendental "Doctrine of Elements" _(Elementarlehre)_, in contrast to the Doctrine of Method. The _Critique of Pure Reason_ follows this scheme of subordinate division, while the _Prolegomena_ co-ordinates all four parts in the manner first mentioned.

Let us anticipate the answers. Pure mathematics is possible, because there are pure or _a priori intuitions_ (space and time), and pure natural science or the metaphysics of phenomena, because there are _a priori concepts_ (categories) _and principles_ of the pure understanding. Metaphysics as a presumptive science of the suprasensible has been possible in the form of unsuccessful attempts, because there are _Ideas_ or concepts of reason which point beyond experience and look as though knowable objects were given through them; but as real science it is not possible, because the application of the categories is restricted to the limits of experience, while the objects thought through the Ideas cannot be sensuously given, and all assumed knowledge of them becomes involved in irresolvable contradictions (antinomies). On the other hand, a science is possible and necessary to teach the correct use of the categories, which may be applied to phenomena alone, and of the Ideas, which may be applied only to our knowledge of things (and our volition), and to determine the origin and the limits of our knowledge--that is to say, a transcendental philosophy. In regard to metaphysics (knowledge from pure reason), then, this is the conclusion reached: Rejection of transcendent metaphysics (that which goes beyond experience), recognition and development of immanent metaphysics (that which remains within the limits of possible experience). It is not possible as a metaphysic of things in themselves; it is possible as a metaphysic of nature (of the totality of phenomena), and as a metaphysic of knowledge (critique of reason).

The interests of the reason are not exhausted, however, by the question, What can we know? but include two further questions, What ought we to do? and, What may we hope? Thus to the metaphysics of nature there is added a metaphysics of morals, and to the critique of theoretical reason, a critique of practical reason or of the will, together with a critique of religious belief. For even if a "knowledge" of the suprasensible is denied to us, yet "practical" grounds are not wanting for a sufficiently certain "conviction" concerning God, freedom, and immortality.

After carrying the question of the possibility of synthetic judgments _a priori_ from the knowledge of nature over to the knowledge of our duty, Kant raises it, in the third place, in regard to our judgment concerning the subjective and objective purposiveness of things, or concerning their beauty and their perfection, and adds to his critique of the intellect and the will a critique of the faculty of aesthetic and teleological _judgment_.

The Kantian philosophy accordingly falls into three parts, one theoretical, one practical (and religious), one aesthetic and teleological.

* * * * *

Before advancing to our account of the first of these parts, a few preliminary remarks are indispensable concerning the presuppositions involved in Kant's critical work and on the method which he pursues. The presuppositions are partly psychological, partly (as the classification of the forms of judgment and inference, and the twofold division of judgments) logical, either in the formal or the transcendental sense, and partly metaphysical (as the thing in itself). Kant takes the first of these from the psychology of his time, by combining the Wolffian classification of the faculties with that of Tetens, and thus obtains six different faculties: lower (sensuous) and higher (intellectual) faculties of cognition, of feeling, and of appetition; or sensibility (the capacity for receiving representations through the way in which we are affected by objects), understanding (the faculty of producing representations spontaneously and of connecting them); the sensuous feelings of pleasure and pain, taste; desire, and will. The understanding in the wide sense is equivalent to the higher faculty of cognition, and divides further into understanding in the stricter sense (faculty of concepts), judgment (faculty of judging), and reason (faculty of inference). Of these the first gives laws to the faculty of cognition or to nature, the second laws to taste, and the third laws to the will.

The most important of the fundamental assumptions concerns the relation, the nature, and the mission of the two faculties of cognition. These do not differ in degree, through the possession of greater or less distinctness--for there are sensuous representations which are distinct and intellectual ones which are not so--but specifically: Sensibility is the faculty of intuitions, understanding the faculty of concepts. Intuitions are particular, concepts general representations. The former relate to objects directly, the latter only indirectly (through the mediation of other representations). In intuition the mind is receptive, in conception it acts spontaneously. "Through intuitions objects are _given_ to us; through concepts they are _thought_." It results from this that neither of the two faculties is of itself sufficient for the attainment of knowledge, for cognition is objective thinking, the determination of objects, the unifying combination or elaboration of a given manifold, the forming of a material content. Rationalists and empiricists alike have been deceived in regard to the necessity for co-operation between the senses and the understanding. Sensibility furnishes the material manifold, which of itself it is not able to form, while the understanding gives the unifying form, to which of itself it cannot furnish a content. "Intuitions without concepts are _blind_" (formless, unintelligible), "concepts without intuitions are _empty_" (without content). In the one case, form and order are wanting; in the other, the material to be formed. The two faculties are thrown back on each other, and knowledge can arise only from their union.

A certain degree of form is attained in sense, it is true, since the chaos of sensations is ordered under the "forms of intuition," space and time, which are an original possession of the intuiting subject, but this is not sufficient, without the aid of the understanding, for the genesis of knowledge. In view of the _a priori_ nature of space and time, though without detraction from their intuitive character (they are immediate particular representations), we may assign pure sensibility to the higher faculty of cognition and speak of an intuiting reason.

The forms of intuition and of thought come from within, they lie ready in the mind _a priori_, though not as completed representations. They are functions, necessary actions of the soul, for the execution of which a stimulus from without, through sensations, is necessary, but which, when once this is given, the soul brings forth spontaneously. The external impulse merely gives the soul the occasion for such productive acts, while their grounds and laws are found in its own nature. In this sense Kant terms them "originally acquired," and in the Introduction to the _Critique of Pure Reason_ declares that although it is indubitable that "all our knowledge begins _with_ experience (impressions of sense), yet it does not all arise _from_ experience." That a representation or cognition is _a priori_[1] does not mean that it precedes experience in time, but that (apart from the merely exciting, non-productive stimulation through impressions already mentioned) it is independent of all experience, that it is not derived or borrowed from experience.

[Footnote 1: The terms _a priori_ representation and pure representation (concept, intuition) are equivalent; but in judgments, on the other hand, there is a distinction. A judgment is _a priori_ when the connection takes place independently of experience, no matter whether the concepts connected are _a priori_ or not. If the former is the case the _a priori_ judgment is pure (mixed with nothing empirical); if the latter, it is mixed.]

The material of intuition and thought is given to the soul, received by it; it arises through the action of objects upon the senses, and is always empirical. Intuition is the only organ of reality; in sensation the presence of a real object as the cause of the sensation is directly revealed. When Kant's transcendental idealism was placed by a reviewer on a level with the empirical idealism of Berkeley, which denies the existence of the external world, he distinctly asserted that it had never entered his mind to question the reality of external things. Further, after the existence of real things affecting the senses had been transformed in his mind from a basis of the investigation into an object of inquiry, he endeavored to defend this assumption (which at first he had naïvely borrowed from the realism of pre-scientific thought) by arguments, but without any satisfactory result.[1]

[Footnote 1: The task of confirming the existence of things in themselves changes under his hands into another, that of proving the existence of external phenomena. "That external objects are real as representations" Berkeley had never disputed.]