Page:Mind (New Series) Volume 9.djvu/376

 362 E. B. C. JONES : metaphorical (i., 297) like Natural Selection the difficulties of which theory are very much lessened by the acceptance of Subjective or Hedonic Selection, which will account for variations on which Natural Selection may act, and removes the tremendous difficulty in the way of understanding by means of Natural Selection cases in which utility results from the co-ordination of a number of variations which are separately useless (i., 300). What we have had up to this point is a prolonged and careful investigation, first of the Mechanical Theory and then of the Theory of Evolution. These as set forth by their most able and accredited expounders, have been invited to say the best they can for themselves, but have revealed both their inherent weakness as systems, and their failure to apply to the concrete phenomena of the real world. Matter has vanished into "non-matter in motion," the account of Evolution given by the Synthetic Philosophy turns out to be on the one hand incoherent, on the other unable to deduce Mind from Matter; Biology as expounded by the ablest biologists, is found to involve teleological and psychical factors. In the Theory of Psycho-physical Parallelism (Part iii.) Mind is explicitly taken into account, and this theory in its various forms endeavours to find an answer to the question : How are psychical changes related to the physical changes in the organism? There is not space to examine at any length the admirable discussion carried through in Part iii. It is first explained how, accepting the dualism of Extended Substance and Thinking Substance formulated by Descartes, Psychology and Physics, dropping the notions of Substance and Cause, have each elaborated conceptions suitable to their own sphere of inquiry, quite apart from any reference to their ultimate co-ordination. On the one side we have Mass, and quantitative relations expressed in equations of Motion ; on the other Consciousness, a flux of presentations ; and the Category of Activity, or Inherent Efficiency, which it should belong to psychologists to investigate, is often by them regarded with suspicion for the very inadequate reason that it is not appropriate in that opposed sphere of science which deals with dead mass, and they substitute for an examination of psychical activity an inquiry into the relations of co- existence and sequence which hold between psychical events and physical movements. The theory of Psycho-physical Parallelism has to be treated under three heads : (1) A series of physical changes or brain-processes.