effort to reduce to a single concept the characters, common to the pure experience, which the special sciences are able to secure. This effort, based upon the special sciences, to describe the common character of the whole world, is, says Avenarius, philosophy. It is the effort to answer the question. What is everything? With so much in mind, we are prepared to understand the following quotation: "In accordance with the principle of least resistance there is accomplished the reference of a single presentation to a general concept, and in so far as this presentation is strange and novel it is made known by this reference. Accordingly, conceptual understanding is a force-economizing, theoretical apprehension of an object, and the totality of objects will be most economically conceived, if they can be apprehended under one general concept. This effort to conceive the totality of objects with the minimum expenditure of force is philosophy. The all-comprehending concept must state what is common to all particular objects. This common aspect mast be given in pure experience. Individual cases of pure experience are secured by means of observation in the special sciences, and the purification of experience, in general, results from the elimination of what is found to not really belong to the objects of experience."[1]
It may appear that we are getting a good way from the system C and its vital series. The digression has its purpose, however, in that it will help us to understand the way in which Avenarius himself viewed his problem, by seeing that problem in its earlier stages. Let us now connect the essay we have just been considering with an article by Avenarius entitled 'The Relation of Psychology to Philosophy.'[2] In the essay just considered, Avenarius describes philosophy as a certain kind of human effort, the effort to get a unified conception of the universe, to ask the question, What is everything? and to tell what it is.
This question, What is the nature of the world ? How is the world constituted? is the question of philosophy. When this question is first asked, there is no doubt concerning our power to know how the world is constituted if we can only find it out. At the same time, psychology contributes little or nothing in giving shape to philosophy. Psychology hardly exists as an independent field, but forms a chapter in some system of metaphysics. The fate of metaphysical systems, however, contradictions discovered within and without, made the problem of knowledge more and more prominent, so that instead of the question. How is the world constituted? we have the question, How is the world known? When this question is first
