The Metaphysic of Morals, as constituting the System of Practical Philosophy, was to follow the 'Critique of the Practical Reason,' as it now does. It falls into two parts: (1) The Metaphysical Principles of Jurisprudence as the Science of Right, and (2) The Metaphysical Principles of Ethics as the Science of Virtue. The whole System forms a counterpart to the 'Metaphysical Principles of the Science of Nature,' which have been already discussed in a separate work (1786). The General Introduction to the 'Metaphysic of Morals' bears mainly on its form in both the Divisions; and the Definitions and Explanations it contains exhibit and, to some extent, illustrate the formal Principles of the whole System.
The Science of Right as a philosophical exposition of the fundamental Principles of Jurisprudence, thus forms the First Part of the Metaphysic of Morals. Taken here by itself—apart from the special Principles of Ethics as the Science of Virtue which follows it—it has to be treated as a System of Principles that originate in Reason; and, as such, it might be properly designated 'The Metaphysic of Right.' But the conception of Right, purely rational in its origin though it be, is also applicable to cases presented in experience; and, consequently, a Metaphysical System of Rights must take into consideration the empirical variety and manifoldness of these cases in order that its Divisions may be complete. For completeness and comprehensiveness are essential and indispensable to the formation of a rational system. But, on the other hand, it is impossible to obtain a complete survey of all the details of experience, and where it may be attempted to approach this, the empirical conceptions embracing those details cannot form integral elements of the system itself, but can only be introduced in subordinate observations, and mainly as furnishing examples illustrative of the General Principles. The only appropriate designation for the First Part of a Metaphysic of Morals, will, therefore, be The Metaphysical Principles of the Science of Right. And, in regard to the practical application to cases, it is manifest that only an approximation to systematic treatment is to be expected, and not the attainment of a System complete in itself. Hence the same method of exposition will be adopted here as was followed in the former work on 'The Metaphysical Principles of the Science of Nature.' The Principles of Right which belong to the rational system will form the leading portions of the text, and details connected with Rights which refer to particular cases of experience, will be appended occasionally in subordinate remarks. In this way a distinction will be clearly made between what is a Metaphysical or rational Principle, and what refers to the empirical Practice of Right.
The reproach of obscurity, and even of a studied indefiniteness affecting the appearance of profound insight, has been frequently raised against my philosophical style of exposition. I do not know how I could better meet or remove this objection than by readily accepting the condition which Garve, a philosopher in the genuine sense of the term, has laid down as a duty incumbent upon every writer, and especially on philosophical authors. And for my part, I would only restrict his injunction by the condition, that it is to be followed only so far as the nature of the science which is to be improved or enlarged will allow.
Garve wisely and rightly demands, that every philosophical doctrine must be capable of being presented in a popular form, if the expounder of it is to escape the suspicion of obscurity in his ideas; that is, it must be capable of being conveyed in expressions that are universally intelligible. I readily admit this, with the exception only of the systematic Critique of the Faculty of Reason, and all that can only be determined and unfolded by it; for all this relates to the distinction of the sensible in our knowledge from the supersensible, which is attainable by Reason. This can never be made popular, nor can any formal Metaphysic as such be popular; although their results may be made quite intelligible to the common reason, which is metaphysical without its being known to be so. In this sphere, popularity in expression is not to be thought of. We are here forced to use scholastic accuracy, even if it should have to bear the reproach of troublesomeness; because it is only by such technical language that the precipitancy of reason can be arrested, and brought to understand itself in face of its dogmatic assertions.
But if pedants presume to address the public in technical phraseology from pulpits or in popular books, and in expressions that are only fitted for the Schools, the fault of this must not be laid as a burden upon the critical philosophers, any more than the folly of the mere wordmonger (logodaedalus) is to be imputed to the grammarian. The laugh should here only turn against the man and not against the science.
It may sound arrogant, egotistical, and, to those who have not yet renounced their old system, even derogatory, to assert 'that before the rise of the Critical Philosophy, there was not yet a philosophy at all.' Now, in order to be able to pronounce upon this seeming presumption, it is necessary to resolve the question as to whether there can really be more than one philosophy. There have, in fact, not only been various modes of philosophizing and of going back to the first principles of Reason in order to found a system upon them, with more or less success; but there must be many attempts of this kind of which every one has its own merit at least for the present. However, as objectively considered there can only be one human Reason, so there cannot be many Philosophies; in other words, there is only one true System of Philosophy founded upon principles, however variously and however contradictorily men may have philosophized over one and the same proposition. Thus the Moralist rightly says, there is only one virtue, and only one doctrine regarding it; that is, one single system connects all the duties of virtue by one principle. The Chemist, in like manner, says there is only one chemistry, that which is expounded by Lavoisier. The Physician, in like manner, says there is only one principle, according to Brown, in the system of classifying Diseases. But because it is held that the new systems exclude all the others, it is not thereby meant to detract from the merit of the older Moralists, Chemists, and Physicians; for without their discoveries, and even their failures, we would not have attained to the unity of the true principle of a complete philosophy in a system. Accordingly, when any one announces a system of philosophy as a production of his own, this is equivalent to saying that 'before this Philosophy there was properly no philosophy.' For should he admit that there had been another and a true philosophy, it would follow that there may be two true systems of philosophy regarding its proper objects; which is a contradiction. If, therefore, the Critical Philosophy gives itself forth as that System before which there had been properly no true philosophy at all, it does no more than has been done, will be done, and even must be done, by all who construct a Philosophy on a plan of their own.
Another objection has been made to my System which is of less general significance, and yet is not entirely without importance. It has been alleged that one of the essentially distinguishing elements of this Critical Philosophy is not a growth of its own, but has been borrowed from some other philosophy, or even from an exposition of Mathematics. Such is the supposed discovery, which a Tübingen Reviewer thinks he has made, in regard to the Definition of Philosophy which the author of the Critique