=Dual Constitution of Man.=--We are all familiar with the notion that man has a dual constitution; that he is a creature both of sense and spirit; that he has a carnal and an ideal nature; a lower and a higher self, a self of appetite and of reason. Now Kant's theory of duty is a peculiar version of this common notion. Man's special ends and purposes all spring from desires and inclinations. These are all for personal happiness and hence without moral worth. They form man's sensuous, appetitive nature, which if not "base" in itself easily becomes so, because it struggles with principle for the office of supplying motives for action. The principle of a law absolutely binding, requires the complete expulsion of the claim of desires to _motivate_ action. (See _Kant's Theory_, pp. 70-79; 132-136; 159-163.) If a man were an animal, he would have only appetite to follow; if he were a god or angel, he would have only reason. Being man, being a peculiar compound of sense and reason, he has put upon him the problem of resisting the natural prompting of inclination and of accepting the duty of acting from reverence for duty. =Criticism of Kant's Theory.=--There is an undoubted fact back of Kant's conception which gives it whatever plausibility it has--the fact that inclinations which are not necessarily evil tend to claim a controlling position, a claim which has to be resisted. The peculiarity of Kant's interpretation lies in its complete and final separation of the two aspects, "higher" and "lower," the appetitive and rational, of man's nature, and it is upon this separation, accordingly, that our discussion will be directed. =I. Duty and the Affections.=--In the first place, Kant's absolute separation of sense or appetite from reason and duty, because of its necessary disparagement of the affections leads to a formal and pedantic view of morality. It is one thing to say that desire as it _first_ shows itself _sometimes_ prompts to a morally inadequate end; it is quite another thing to say that _any_ acceptance of an end of desire as a motive is morally wrong--that the act to be right must be first brought under a conscious acknowledgment of some law or principle. Only the exigencies of a ready-made theory would lead any one to think that habitual purposes that express the habitually dominant tendencies and powers of the agent, may not suffice to keep morally sound the main tenor of behavior; that it is impossible for regard for right ends to become organized into character and to be fused into working unity with natural impulses. Only a metaphysical theory regarding the separation of sense and reason in man leads to the denial of this fact.