The problem which we must put at the center of ethics is a purely psychological one. For, without doubt, the discovery of the motives or laws of any kind of behavior, and therefore of moral behavior, is a purely psychological affair. Only the empirical science of the laws which describe the life of the soul can solve this problem. One might wish to derive from this a supposedly profound and destructive objection to our formulation of the problem. For, one might say, “In such case there would be no ethics at all; what is called ethics would be nothing but a part of psychology!” I answer, “Why shouldn't ethics be a part of psychology?” Perhaps in order that the philosopher have his science for himself and govern autonomously in this sphere? He would, indeed, thereby be freed of many burdensome protests of psychology. If he laid down a command, “Thus shall man act,” he would not have to pay attention to the psychologist who said to him, “But man cannot act so, because it contradicts psychological laws!” I fear greatly that here and there this motive, though hidden, is at work. However, if one says candidly that “there is no ethics,” because it is not necessary to label a part of psychology by a special name, then the question is merely terminological.

It is a poor recommendation of the philosophical spirit of our age that we so often attempt to draw strict lines of division between the sciences, to separate ever new disciplines, and to prove their autonomy. […]