The point of departure in Kant’s exposition is the existence in all men of a sense of duty. Moral relations subsist only between moral beings. All men possess a sense of duty,—therefore all men are moral beings, therefore all are morally equal,—therefore no one may be used as a mere tool for the benefit of others, but is to be treated as worth while on his own account. Thus runs the argument. The sense of duty is the consciousness of being bound to render implicit obedience to a categorical imperative. Our rational nature tells us categorically what is right to do. Our rational nature issues absolute commands. The sense of duty is man’s response to them. Kant does not for a moment imply that either he or anyone else has ever adequately obeyed. The moral dignity, the moral equality of men, does not depend on the obedience but on the consciousness of the obligation to obey—on acknowledged subjection to the command. The actual moral performances of some men are certainly better than those of others; but of no one, not even of the best of men, can it be shown that the moral principle in its purity, that is, unadulterated by baser incentives, was ever the actuating motive of his conduct. The different members of the human species differ morally in degree, but are of the same moral kind, being distinguished from the lower animals not because they obey the moral law, but because they recognize the obligation to obey it. This sort of consciousness may be dim in some, but it exists in all. The most brutal murderer is dimly aware of the holy law which he has transgressed. The great dictum of the universal moral equality of mankind is thus made to depend on an assumed fact. If this fact can be successfully disputed, the dictum itself is imperilled. It has been disputed, not flippantly, but most seriously, and it is in my opinion obnoxious to fatal objections. I do not indeed believe it possible to establish the negative, to wit, that the sense of duty does not lurk somewhere, is not latent somewhere in the consciousness of persons morally the most obtuse; but I hold it to be impossible to prove the affirmative, to wit, that a sense of duty does exist in all human beings, even in the most degraded. Kant’s dictum of equality depends on making good the affirmative proposition, but this he has failed to do.