This brings us back to the 'Kritik der Reinen Erfahrung,' but it brings us back prepared to observe the application of the method of the 'Kritik' to the description of philosophy as a natural process. If the question, 'How do we conceive the world?' in this new form can be answered with any measure of success, we may be able to reach some conclusions about the conditions on which the fate of systems of philosophy depends, and be able to state what conditions must be fulfilled by a philosophy which shall endure.
It was remarked above that the appearance of a problem means a certain restlessness on the part of him who sees the problem. We ought to distinguish between real problems and pretended problems. By real problems I mean questions that strike us as really problematic, questions whose solution one way or another makes a difference to us, questions which are problems not merely by virtue of a definition, but by virtue of the kind of interest they arouse. Besides the genuine problems there are problems which do not show any really problematic character. The problem about solipsism is a problem of this sort. A healthy man can not possibly find any real problem here. We may admit that the reality of other selves is problematic, but we shall be quite unable to experience the problematic character which we admit.
Progress in science and philosophy is largely due to a capacity for discovering real problems. Oriental peoples have this genius in a far less degree than Europeans. The problems of the Oriental consciousness are solved. Only the Western consciousness is tormented with doubts about reality, duty, the past and the future. Avenarius loves to dwell on the satisfaction and relief which the solution of a real problem affords, and on the teasing, restless, unsatisfied state which accompanies an unsolved real problem.
The distinction between the real problem and the artificial problem would appear to be a real and important distinction from the psychological point of view, where the purpose is an accurate description of experience. For this point of view, the so-called artificial problem is no problem at all. That is, its parallel brain-process can not be the one which gives rise to the problematic character. Accordingly, the word 'problem' will designate, in what remains to be said about Avenarius, always the real and genuine problem, the problem with the biological disturbance behind it. Evidently a philosophy which is to endure, which shall be, as Avenarius puts it, 'biologisch haltbar' must be an E-value or a group of E-values which express a permanent stability of the system C. These E-values have, in the process of physiological selection which marks the evolution of habit, come to prevail over other E-values. They have come to prevail because they represent the constant character of nature.
