It is quite clear that he is not supposed to be an Aristotle.  He does not represent all the sciences, and no one expects him to lecture on mathematics, mechanics, physics, chemistry, zooelogy, botany, economics, politics, and various other disciplines.  There was a time when he might have been expected to teach all that men could know, but that time is long past.

Nevertheless, there is quite a group of sciences which are regarded as belonging especially to his province; and although a man may devote a large part of his attention to some one portion of the field, he would certainly be thought remiss if he wholly neglected the rest.  This group of sciences includes logic, psychology, ethics and aesthetics, metaphysics, and the history of philosophy.  I have not included epistemology or the “theory of knowledge” as a separate discipline, for reasons which will appear later (Chapter XIX); and I have included the history of philosophy, because, whether we care to call this a special science or not, it constitutes a very important part of the work of the teacher of philosophy in our day.

Of this group of subjects the student who goes to the university to study philosophy is supposed to know something before he leaves its walls, whatever else he may or may not know.

It should be remarked, again, that there is commonly supposed to be a peculiarly close relation between philosophy and religion.  Certainly, if any one about a university undertakes to give a course of lectures on theism, it is much more apt to be the professor of philosophy than the professor of mathematics or of chemistry.  The man who has written an “Introduction to Philosophy,” a “Psychology,” a “Logic,” and an “Outlines of Metaphysics” is very apt to regard it as his duty to add to the list a “Philosophy of Religion.”  The students in the theological seminaries of Europe and America are usually encouraged, if not compelled, to attend courses in philosophy.

Finally, it appears to be definitely accepted that even the disciplines that we never think of classing among the philosophical sciences are not wholly cut off from a connection with philosophy.  When we are occupied, not with adding to the stock of knowledge embraced within the sphere of any special science, but with an examination of the methods of the science, with, so to speak, a criticism of the foundations upon which the science rests, our work is generally recognized as philosophical.  It strikes no one as odd in our day that there should be established a “Journal of Philosophy, Psychology, and Scientific Methods,” but we should think it strange if some one announced the intention to publish a “Journal of Philosophy and Comparative Anatomy.”  It is not without its significance that, when Mach, who had been professor of physics at Prague, was called (in 1895) to the University of Vienna to lecture on the history and theory of the inductive sciences, he was made, not professor of physics, but professor of philosophy.