In view of the complete systematic unity of reason, there can only be one ultimate end
of all the operations of the mind. To this all other aims are subordinate, and nothing more than means for its attainment. This ultimate end is the destination of man, and the philosophy which relates to it is termed moral philosophy. The superior position occupied by moral philosophy, above all other spheres for the operations of reason, sufficiently indicates the reason why the ancients always included the idea—and in an especial manner—of moralist in that of philosopher. Even at the present day, we call a man who appears to have the power of self-government, even although his knowledge may be very limited, by the name of philosopher.
The legislation of human reason, or philosophy
, has two objects- nature
—and thus contains not only the laws of nature
, but also those of ethics
, at first in two separate systems, which, finally, merge into one grand philosophical system of cognition. The philosophy of nature relates to that which is
, that of ethics to that which ought to be
But all philosophy is either cognition on the basis of pure reason, or the cognition of reason on the basis of empirical principles. The former is termed pure, the latter empirical philosophy.
The philosophy of pure reason is either propaedeutic, that is, an inquiry into the powers of reason in regard to pure a priori cognition, and is termed critical philosophy; or it is, secondly, the system of pure reason—a science containing the systematic presentation of the whole body of philosophical knowledge, true as well as illusory, given by pure reason—and is called metaphysic. This name may, however, be also given to the whole system of pure philosophy, critical philosophy included, and may designate the investigation into the sources or possibility of a priori cognition, as well as the presentation of the a priori cognitions which form a system of pure philosophy—excluding, at the same time, all empirical and mathematical elements.
Metaphysic is divided into that of the speculative
and that of the practical use
of pure reason, and is, accordingly, either the metaphysic of nature
, or the metaphysic of ethics
. The former contains all the pure rational principles
—based upon conceptions alone (and thus excluding mathematics)—of all theoretical cognition
; the latter, the principles which determine and necessitate a priori all action
. Now moral philosophy alone contains a code of laws—for the regulation of our actions—which are deduced from principles entirely a priori. Hence the metaphysic of ethics is the only pure moral philosophy
, as it is not based upon anthropological or other empirical considerations. The metaphysic of speculative reason is what is commonly called metaphysic
in the more limited sense. But as pure moral philosophy properly forms a part of this system of cognition, we must allow it to retain the name of metaphysic, although it is not requisite that we should insist on so terming it in our present discussion.
All pure a priori cognition forms, therefore, in view of the peculiar faculty which originates it, a peculiar and distinct unity; and metaphysic is the term applied to the philosophy which attempts to represent that cognition in this systematic unity
. The speculative part of metaphysic
, which has especially appropriated this appellation—that which we have called the metaphysic of nature—and which considers everything, as it is
(not as it ought to be
), by means of a priori conceptions, is divided in the following manner.