II.4. The History of Pure Reason

This title stands here only in order to indicate one remaining division of the system, which future workers must complete. 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 works of those who have laboured in this field—a glance which reveals [many stately] structures, but in ruins only.

It is a very notable fact, although it could not have been otherwise, that in the infancy of philosophy men began where we should incline to end, namely, with the knowledge of God, occupying themselves with the hope, or rather indeed with the specific nature, of another world. However gross the religious concepts generated by the ancient practices which still persisted in each community from an earlier more barbarous state, this did not prevent the more enlightened members from devoting themselves to free investigation of these matters; and they easily discerned that there could be no better ground or more dependable way of pleasing the invisible power that governs the world, and so of being happy in another world at least, than by living the good life. Accordingly theology and morals were the two motives, or rather the two points of reference, in all those abstract enquiries of reason to which men came to devote themselves. It was chiefly, however, the former that step by step committed the purely speculative reason to those labours which afterwards became so renowned under the name of metaphysics.

I shall not here attempt to distinguish the periods of history in which this or that change in metaphysics came about, but shall only give a cursory sketch of the various ideas which gave rise to the chief revolutions [in metaphysical theory]. And here I find that there are three issues in regard to which the most noteworthy changes have taken place in the course of the resulting controversies.

1. In respect of the object of all our ‘knowledge through reason’, some have been mere sensualists, others mere intellectualists. Epicurus may be regarded as the outstanding philosopher among the former, and Plato among the latter. The distinction between the two schools, subtle as it is, dates from the earliest times; and the two positions have ever since been maintained in unbroken continuity. Those of the former school maintained that reality is to be found solely in the objects of the senses, and that all else is fiction; those of the latter school, on the other hand, declared that in the senses there is nothing but illusion, and that only the understanding knows what is true. The former did not indeed deny reality to the concepts of the understanding; but this reality was for them merely logical, whereas for the others it was mystical. The former conceded intellectual concepts, but admitted sensible objects only. The latter required that true objects should be purely intelligible, and maintained that by means of the pure understanding we have an intuition that is unaccompanied by the senses—the senses, in their view, serving only to confuse the understanding.

2. In respect of the origin of the modes of ‘knowledge through pure reason’, the question is as to whether they are derived from experience, or whether in independence of experience they have their origin in reason. Aristotle may be regarded as the chief of the empiricists, and Plato as the chief of the noologists. Locke, who in modern times followed Aristotle, and Leibniz, who followed Plato (although in considerable disagreement with his mystical system), have not been able to bring this conflict to any definitive conclusion. However we may regard Epicurus, he was at least much more consistent in this sensual system than Aristotle and Locke, inasmuch as he never sought to pass by inference beyond the limits of experience. This is especially true as regards Locke, who, after having derived all concepts and principles from experience, goes so far in the use of them as to assert that we can prove the existence of God and the immortality of the soul with the same conclusiveness as any mathematical proposition—though both lie entirely outside the limits of possible experience.

3. In respect of method.—If anything is to receive the title of method, it must be a procedure in accordance with principles. We may divide the methods now prevailing in this field of enquiry into the naturalistic and the scientific. The naturalist of pure reason adopts as his principle that through common reason, without science, that is, through what he calls sound reason, he is able, in regard to those most sublime questions which form the problem of metaphysics, to achieve more than is possible through speculation. Thus he is virtually asserting that we can determine the size and distance of the moon with greater certainty by the naked eye than by mathematical devices. This is mere misology, reduced to principles; and what is most absurd of all, the neglect of all artificial means is eulogised as a special method of extending our knowledge. For as regards those who are naturalists from lack of more insight, they cannot rightly be blamed. They follow common reason, without boasting of their ignorance as a method which contains the secret how we are to fetch truth from the deep well of Democritus. Quod sapio, satis est mihi; non ego curo, esse quod Arcesilas aerumnosique Solones is the motto with which they may lead a cheerful and praiseworthy life, not troubling themselves about science, nor by their interference bringing it into confusion.

As regards those who adopt a scientific method, they have the choice of proceeding either dogmatically or sceptically; but in any case they are under obligation to proceed systematically. I may cite the celebrated Wolff as a representative of the former mode of procedure, and David Hume as a representative of the latter, and may then, conformably with my present purpose, leave all others unnamed. The critical path alone is still open. If the reader has had the courtesy and patience to accompany me along this path, he may now judge for himself whether, if he cares to lend his aid in making this path into a high-road, it may not be possible to achieve before the end of the present century what many centuries have not been able to accomplish; namely, to secure for human reason complete satisfaction in regard to that with which it has all along so eagerly occupied itself, though hitherto in vain.