me not "Thou must," but "Thou shalt." If I were not free this "shall" would be an absurdity if there did not correspond to it a "can."
The moral freedom of man is certainly a complicated question, carrying with it no less contradictions than the ideality of time and space. Since this freedom comes to expression in actions which belong to the chain of cause and effect they are necessary. The same world of phenomena, as such falling beneath the actions are at the same time free and necessary. Moreover, freedom arises in the timeless, intelligible world, while cause and effect always fall in a particular time. The same time-determined action has thus a time as well as a cause in time.
But what is now the moral law which from the world of things in themselves, the "World of the Understanding," extends its working right into the world of appearances, the world of the "senses," and subordinates these to itself? Since it springs from the world of the understanding, its determining ground can only be in pure reason. It must be of purely formal nature, because it must remain fully free from all relation to the world of the senses, which would at once involve a relation of cause and effect, a determining ground of the will which would at once annihilate its freedom.
"There is, however," says Kant, in his "Critique of Practical Reason," "besides the matter of the law, nothing further contained than the law-giving form. Thus the law-giving form, so far as it is contained in the maxim, and that alone, can constitute a determining ground of free will.”
From that he draws the following "Fundamental Law of Pure Practical Reason":—
"Act so that the maxim of thy action may be a principle of universal legislation."
This principle is by no means startlingly new. It forms only the philosophic translation of the ancient precept, to do unto others as we would be done by. This is only the declaration that this precept forms a revelation of an intelligible world; a revelation which
