Page:Mind (New Series) Volume 9.djvu/404

390 CRITICAL NOTICES : work which cannot induce any feeling of irritation. However radically one may disagree with the position of Mr. Petzoldt, there is no after-vexation due to the feeling that one has been worrying over difficulties that are mere confusions and nothing more. Whether one agrees with the exposition or not, one cannot but feel that one's own convictions are made more clear to one's self by means of it. The conviction that psychical processes cannot furnish their own explanation, but can be unequivocally determined only through their dependence on brain processes that can be deter- mined, is the soul and inspiration of the new movement, of which the late Dr. Avenarius is the chief exponent. Avenarius, says Mr. Petzoldt (p. 350), was the first to feel deeply the need of bringing the movements of the mind under the firm control of a genuine science. He became convinced that the attempt to understand psychical events by referring them to other more familiar psychical events was futile. It could result at best in the establishment of certain uniformities (Kegelmdssigkeiten) that were constantly being broken, but never in the establishment of laws. The only genuine explanation, the only form of explanation that could make psychical process scientifically thinkable must be such as to show in detail the absolute determinateness of the process. So long as the slightest vestige of indeterminateness remained, there could be no science of Psychology. This was the conviction of Avenarius. A very clear and striking statement of the way in which one is to convince one's self of the truth of this conviction and fall irresistibly into line with Avenarius is given in the first intro- ductory part of the present volume. It consists essentially in the following argument : The only intelligible principle of explanation is that founded on the thoroughgoing unideterminateness (ein- deutige Bestimmung) of events. Such unideterminateness is not anywhere traceable within the mental sphere. Mental processes must, therefore, either remain permanently inexplicable or be explained through their connexion with material processes, for these alone proceed unideterminately. As all known facts agree in showing that the only material processes in immediate relation with psychical processes are the processes of the brain, it follows irresistibly that if there is to be a science of mind at all, psychical processes must be conceived of as the dependent concomitants of brain processes, and receive their unideterminateness through their connexion with these. This is not materialism or any other " ism," urges Mr. Petzoldt in conclusion. It is a simple fact, for if it be not a fact, then mental science is an illusion. Such is Mr. Petzoldt's startling but clearly defined attempt to set up the doctrine of psycho-physical parallelism as the funda- mental incontrovertible fact of mental science. Let us now examine this attempt more closely. Mr. Petzoldt asks us to focus our attention on some single psychical event and to ask ourselves how we intend understanding it. The ready answer will no