The fundamental idea of a philosophy of pure reason prescribes itself this division. It is therefore architectonical, adequate to its essential aims, and not technical only, contrived according to any observed similarities, and, as it were, at haphazard. For that very reason such a division is unchangeable and of legislative authority. There are, however, a few points which might cause misgivings, and weaken our conviction of its legitimate character.
First of all, how can I expect knowledge a priori, that is metaphysic, of objects so far as they are given to our senses, that is a posteriori? and how is it possible to know the nature of things according to principles a priori, and thus to arrive at a rational physiology? Our answer is, that we take nothing from experience beyond what is necessary to give us an object, either of the external or of the internal sense. The former is done by the mere concept of matter (impermeable, lifeless extension), the latter through the concept of a thinking being (in the empirical internal representation, I think). For the rest, we ought in the whole metaphysical treatment of these objects to abstain from all empirical principles, which to the concept of matter might add any kind of experience for the purpose of forming any judgments on these objects.
Secondly. What becomes of empirical psychology, which has always maintained its place in metaphysic and from which, in our time, such great things were expected for throwing light on metaphysic, after all hope had been surrendered of achieving anything useful a priori? I answer, it has its place where the proper (empirical) study of nature must be placed, namely, by the side of applied philosophy, to which pure philosophy supplies the principles a priori; thus being connected, but not to be confounded with it. Empirical psychology, therefore, must be entirely banished from metaphysic, and is excluded from it by its very idea. According to the tradition of the schools, however, we shall probably have to allow to it (though as an episode only) a small corner in metaphysic, and this from economical motives, because, as yet, it is not so rich as to constitute a study by itself, and yet too important to be banished entirely and to be settled in a place where it would find still less affinity than in metaphysic. It is, therefore, a stranger only, who has been received for a long time and whom one allows to stay a little longer, until he can take up his own abode in a complete system of anthropology, the pendant to the empirical doctrine of nature.
This then is the general idea of metaphysic which, as in the beginning more was expected of it than could justly be demanded, fell into general disrepute after these pleasant expectations had proved fallacious. The whole course of our critique must have convinced us sufficiently that, although metaphysic cannot supply the foundation of religion, it must always remain its bulwark, and that human reason, being dialectical by its very nature, cannot do without a science which curbs it and, by means of a scientific and perfectly clear self-knowledge, prevents the ravages which otherwise this lawless speculative reason would certainly commit both in morals and religion. We may be sure, therefore, that, in spite of the coy or contemptuous airs assumed by those who judge a science, not according to its nature, but according to its accidental effects, we shall always return to it as to a beloved one with whom we have quarrelled, because reason, as essential interests are here at stake, cannot rest till it has either established correct views or destroyed those which already exist.
Metaphysic, therefore, that of nature as well as that of morals, and particularly the criticism of our adventurous reason, which forms the introduction and preparation of it, constitute together what may be termed philosophy in the true sense of the word. Its only goal is wisdom, and the path to it science, the only path which, if once opened, is never grown over again, and can never mislead. Mathematics, natural science, even the empirical knowledge of men, have, no doubt, a high value, as means for the most part to accidental, but yet in the end necessary and essential aims of mankind. But they have that value only by means of that knowledge of reason based on pure concepts which, call it as you may, is in reality nothing but metaphysic.
For the same reason metaphysic is also the completion of the whole culture of human reason, which is indispensable, although one may discard its influence as a science with regard to certain objects. For it enquires into reason according to its elements and highest maxims, which must form the very foundation of the possibility of some sciences, and of the use of all. That, as mere speculation, it serves rather to keep off error than to extend knowledge does not detract from its value, but, on the contrary, confers upon it dignity and authority by that censorship which secures general order and harmony, ay, the well-being of the scientific commonwealth, and prevents its persevering and successful labourers from losing sight of the highest aim, the general happiness of all mankind.
1 Cosmical concept is meant here for a concept relating to what must be of interest to everybody: while I determine the character of a science, according to scholastic concepts, if I look upon it only as one of many crafts intended for certain objects.
2 It must not be supposed that I mean by this what is commonly called physica generalis, and which is rather mathematics, than a philosophy of nature. For the metaphysic of nature is entirely separate from mathematics, and does not enlarge our knowledge as much as mathematics; but it is, nevertheless, very important, as supplying a criticism of the pure knowledge of the understanding that should be applied to nature. For want of its guidance, even mathematicians, given to certain common concepts which in reality are metaphysical, have unconsciously encumbered physical science with hypotheses which vanish under a criticism of those principles, without however causing the least detriment to the necessary employment of mathematics in this field.
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Method of Transcendentalism
Chapter IV
The History Of Pure Reason
This title stands here only in order to indicate the place in the system which remains empty for the present and has to be filled hereafter. I content myself with casting a cursory glance, from a purely transcendental point of view, namely, that of the nature of pure reason, on the labours of former philosophers, which presents to my eyes many structures, but in ruins only.
It is very remarkable, though naturally it could not well have been otherwise, that in the very infancy of philosophy men began where we should like to end, namely, with studying the knowledge of God and the hope or even the nature of a future world. However crude the religious concepts might be which owed their origin to the old customs, as remnants of the savage state of humanity, this did not prevent the more enlightened classes from devoting themselves to free investigations of these matters, and they soon perceived that there could be no better and surer way of pleasing that invisible power which governs the world, in order to be happy at least in another world, than good conduct. Thus theology and morals became the two springs, or rather the points of attraction for all abstract enquiries of reason in later times, though it was chiefly the former which gradually drew speculative reason into those labours which afterwards became so celebrated under the name of metaphysic.
I shall not attempt at present to distinguish the periods of history in which this or that change of metaphysic took place, but only draw a rapid sketch of the difference of the ideas which caused the principal revolutions in metaphysic. And here I find three aims with which the most important changes on this arena were brought about.
1. With reference to the object of all knowledge of our reason, some philosophers were mere sensualists, others mere intellectualists. Epicurus may be regarded as the first among the former, Plato as the first among the latter. The distinction of these two schools, subtle as it is, dates from the earliest days, and has long been maintained. Those who belong to the former school maintained that reality exists in the objects of the senses alone, everything else being imagination; those of the second school, on the contrary, maintained, that in the senses there is nothing but illusion, and that the true is known by the understanding only. The former did not, therefore, deny all real
ity to the concepts of the understanding, but that reality was with them logical only, with the others it was mystical. The former admitted intellectual concepts, but accepted sensible objects only. The latter required that true objects should be intelligible only, and maintained an intuition peculiar to the understanding, separated from the senses which, in their opinion, could only confuse it.
2. With reference to the origin of the pure concepts of reason, and whether they are derived from experience, or have their origin independent of experience, in reason. Aristotle may be considered as the head of the empiricists, Plato as that of the noologists. Locke, who in modern times followed Aristotle, and Leibniz, who followed Plato (though at a sufficient distance from his mystical system), have not been able to bring this dispute to any conclusion. Epicurus at least was far more consistent in his sensual system (for he never allowed his syllogisms to go beyond the limits of experience) than Aristotle and Locke, more particularly the latter, who, after having derived all concepts and principles from experience, goes so far in their application as to maintain that the existence of God and the immortality of the soul (though both lie entirely outside the limits of all possible experience) could be proved with the same evidence as any mathematical proposition.
3. With reference to method. If anything is to be called method, it must be a procedure according to principles. The method at present prevailing in this field of enquiry may be divided into the naturalistic and the scientific. The naturalist of pure reason lays it down as his principle that, with reference to the highest questions which form the problems of metaphysic, more can be achieved by means of common reason without science (which he calls sound reason), than through speculation. This is the same as if we should maintain that the magnitude and distance of the moon can be better determined by the naked eye than by roundabout mathematical calculations. This is pure misology reduced to principles, and, what is the most absurd, the neglect of all artificial means is recommended as the best way of enlarging our knowledge. As regards those who are naturalists because they know no better, they are really not to be blamed. They simply follow ordinary reason, but they do not boast of their ignorance, as the method which contains the secret how we are to fetch the truth from the bottom of the well of Democritus. 'Quod sapio satis est mihi, non ego curo, esse quod Arcesilas aerumnosique Solones' (Pers.), is the motto with which they may lead a happy and honoured life, without meddling with science or muddling it.
As regards those who follow a scientific method, they have the choice to proceed either dogmatically or sceptically, but at all events, systematically. When I have mentioned in relation to the former the celebrated Wolf, and in relation to the other David Hume, I may for my present purpose leave all the rest unnamed.
The only path that is still open is the critical. If the reader has been kind and patient enough to follow me to the end along this path, he may judge for himself whether, if he will help, as far as in him lies, towards making this footpath a highroad, it may not be possible to achieve, even before the close of the present century, what so many centuries have not been able to achieve, namely, to give complete satisfaction to human reason with regard to those questions which have in all ages exercised its desire for knowledge, though hitherto in vain.
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Supplement I
Motto to Second Edition
Baco De Verulamio
Instauratio magna: Praefatio
De nobis ipsis silemus: de re autem, quae agitur, petimus, ut homines eam non opinionem, sed opus esse cogitent; ac pro certo habeant, non sectae nos alicujus aut placiti, sed utilitatis et amplitudinis humanae fundamental moliri. Deinde ut suis commodis aequi…in commune consultant,…et ipsi in partem veniant. Praeterea, ut bene sperent, neque Instaurationem nostram ut quiddam infinitum et ultra mortale fingant, et animo concipiant; quum revera sit infiniti errors finis et terminus legitimus.
Supplement II
Preface to the Second Edition. 1787.
Whether the treatment of that class of knowledge with which reason is occupied follows the secure method of a science or not, can easily be determined by the result. If, after repeated preparations, it comes to a standstill, as soon as its real goal is approached, or is obliged, in order to reach it, to retrace its steps again and again, and strike into fresh paths; again, if it is impossible to produce unanimity among those who are engaged in the same work, as to the manner in which their common object should be obtained, we may be convinced that such a study is far from having attained to the secure method of a science, but is groping only in the dark. In that case we are conferring a great benefit on reason, if we only find out the right method, though many things should have to be surrendered as useless, which were comprehended in the original aim that had been chosen without sufficient reflection.
That Logic, from the earliest times, has followed that secure method, may be seen from the fact that since Aristotle it has not had to retrace a single step, unless we choose to consider as improvements the removal of some unnecessary subtleties, or the clearer definition of its matter, both of which refer to the elegance rather than to the solidity of the science. It is remarkable also, that to the present day, it has not been able to make one step in advance, so that, to all appearance, it may be considered as completed and perfect. If some modern philosophers thought to enlarge it, by introducing psychological chapters on the different faculties of knowledge (faculty of imagination, wit, etc.), or metaphysical chapters on the origin of knowledge, or the different degrees of certainty according to the difference of objects (idealism, scepticism, etc.), or lastly, anthropological chapters on prejudices, their causes and remedies, this could only arise from their ignorance of the peculiar nature of logical science. We do not enlarge, but we only disfigure the sciences, if we allow their respective limits to be confounded: and the limits of logic are definitely fixed by the fact, that it is a science which has nothing to do but fully to exhibit and strictly to prove all formal rules of thought (whether it be a priori or empirical, whatever be its origin or its object, and whatever be the impediments, accidental or natural, which it has to encounter in the human mind).
That logic should in this respect have been so successful, is due entirely to its limitation, whereby it has not only the right, but the duty, to make abstraction of all the objects of knowledge and their differences, so that the understanding has to deal with nothing beyond itself and its own forms. It was, of course, far more difficult for reason to enter on the secure method of science, when it has to deal not with itself only, but also with objects. Logic, therefore, as a kind of preparation (propaedeutic) forms, as it were, the vestibule of the sciences only, and where real knowledge is concerned, is presupposed for critical purposes only, while the acquisition of knowledge must be sought for in the sciences themselves, properly and objectively so called.
If there is to be in those sciences an element of reason, something in them must be known a priori, and knowledge may stand in a twofold relation to its object, by either simply determining it and its concept (which must be supplied from elsewhere), or by making it real also. The former is theoretical, the latter practical knowledge of reason. In both the pure part, namely, that in which reason determines its object entirely a priori (whether it contain much or little), must be treated first, without mixing up with it what comes from other sources; for it is bad economy to spend blindly whatever comes in, and not to be able to determine, when there is a stoppage, which part of the income can bear the expenditure, and where reductions must be made.
Mathematics and physics are the two theoretical sciences of reason, which have to determine their objects a priori; the former quite purely, the latter partially so, and partially from other sources of knowledge besides reason.
Mathematics, from the earliest times to which the history of human reason can reach, has followed, among that wonderful people of the Greeks, the safe way of a science. But it must not be supposed that it was as easy for mathematics as for log
ic, in which reason is concerned with itself alone, to find, or rather to make for itself that royal road. I believe, on the contrary, that there was a long period of tentative work (chiefly still among the Egyptians), and that the change is to be ascribed to a revolution, produced by the happy thought of a single man, whose experiment pointed unmistakably to the path that had to be followed, and opened and traced out for the most distant times the safe way of a science. The history of that intellectual revolution, which was far more important than the discovery of the passage round the celebrated Cape of Good Hope, and the name of its fortunate author, have not been preserved to us. But the story preserved by Diogenes Laertius, who names the reputed author of the smallest elements of ordinary geometrical demonstration, even of such as, according to general opinion, do not require to be proved, shows, at all events, that the memory of the revolution, produced by the very first traces of the discovery of a new method, appeared extremely important to the mathematicians, and thus remained unforgotten. A new light flashed on the first man who demonstrated the properties of the isosceles triangle1 (whether his name was Thales or any other name), for he found that he had not to investigate what he saw in the figure, or the mere concept of that figure, and thus to learn its properties; but that he had to produce (by construction) what he had himself, according to concepts a priori, placed into that figure and represented in it, so that, in order to know anything with certainty a priori, he must not attribute to that figure anything beyond what necessarily follows from what he has himself placed into it, in accordance with the concept.
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