It is to men of science rather than to philosophers that we owe the ‘descriptive theory’ of scientific concepts which, within the last few years, has gone far to revolutionise the prevailing attitude of philosophy to science.  Concepts, such as ‘mass,’ ‘energy,’ and the like, are no longer held to express realities the denial of which would be treason to science; they are simply descriptive notions whose truth consists in their utility:  that is to say, in their ability to comprehend all the relevant facts in a simple description.  And, in the same way, scientific principles are of the nature of postulates, whose justification is no necessary law of thought, but must rather be sought in the results of scientific investigation.

These three doctrines—­the descriptive theory of science, the practical nature of knowledge as it is brought out by psychological analysis, and the special claims of the moral consciousness—­have combined to bring about a tendency strongly opposed to the older idealist tradition, the tendency to regard practical results as the sole test of truth.

This conception is put forward now in philosophical literature as a new and independent point of view.  The point of view is only in process of being hardened into a theory; but, under the name of Pragmatism, it has already become the subject of a vigorous propaganda.  With the value of this doctrine as a general theory of reality we need not at present concern ourselves.  In spite of the high claims it makes for the theoretical significance of moral ideas, its adherents have not as yet devoted much attention to the question of the worth of these moral ideas and the criteria by which that worth may be determined.  Yet this surely is the fundamental question for ethical theory.  On the other hand, as against a merely theoretical interpretation of the universe, into which the moral element enters only as a sort of loosely-connected appendix, the pragmatists are amply justified.  Practical ends are prior to theoretical explanations of what happens.  But practical ends vary, and some measure of their relative values is needed.

There is one thing which all reasoning about morality assumes and must assume; and that is morality itself.  The moral concept—­whether described as worth or as duty or as goodness—­cannot be distilled out of any knowledge about the laws of existence or of occurrence.  Nor will speculation about the real conditions of experience yield it, unless adequate recognition be first of all given to the fact that the experience which is the subject-matter of philosophy is not merely a sensuous and thinking, but also a moral, experience.  The approval of the good, the disapproval of the evil, and the preference of the better:  these would seem to be basal facts for an adequate philosophical theory:  and they imply the striving for a best—­however imperfect the apprehension of that best may always remain.  Only when these facts—­the characteristic facts of moral experience—­are recognised as constituents of the experience which is our subject-matter, are we in a position profitably to enquire what is good and what evil, and how the best is to be conceived.