632 GENERAL PSYCHOLOGY 



I have already mentioned that the simplest mental elements which 

 we can distinguish correspond to very complex physiological processes. 

 What psychologically appears quite simple is a physiological multiplic- 

 ity. In a simple mental element must be combined what physiolog- 

 ically covers several moments and a whole region of the brain. But 

 there is also another thing which is of importance here. Mental ele- 

 ments are qualitatively different one from another, while we have 

 reason to believe that the correspondent processes in the brain are 

 only different as regards intensity, direction, and combination. What 

 psychologically appears as differences of quality is from the point 

 of view of physical science to be regarded as differences of quantity. 

 Continuity, then, is more easily demonstrated from the physical 

 than from the psychological point of view. The old maxim that 

 nature does not move in bounds cannot be carried out in psychology 

 as entirely as in physical science. 



From these circumstances some thinkers have concluded that a 

 science treating of mental life is only possible, if for the relation 

 between mental states we can substitute the relation between the 

 corresponding states of the brain. In order to be a science, psycho- 

 logy must be transformed into physiology. If not, it should, accord- 

 ing to these philosophers, be impossible to approach the ideal of 

 scientific understanding, i. e., the pointing-out of continuity and 

 equivalence between phenomena. But we always begin by discovering 

 causal relations between qualitatively different phenomena, and not 

 till later on can we take up the task of substituting for this element- 

 ary causality a more perfect causal relation with continuity and 

 equivalence between the phenomena. Though in the domain of psych- 

 ology we are scarcely able to go further than to the elementary 

 causality, because we have no mental units and so no thorough 

 quantitative methods, yet this fact does not exclude the right to 

 admit a causal relation between mental states. And this is not only 

 a right, but also a necessity. If there exists a causal relation between 

 the correspondent processes of the brain, there must also be at least 

 an indirect causal relation between the mental states. Moreover, 

 we have only quite schematical constructions of the corresponding 

 processes of the brain, constructions which are based on analogy 

 with the directly observed and analyzed mental states. From these 

 states we draw our conclusions as to the corresponding processes of 

 the brain. This conclusion cannot be true, if psychological observa- 

 tions and analysis are not correct. The independence of psychology 

 is thus presupposed. 



Perhaps the simplicity and the qualitative character of the 

 mental elements are to be regarded as the results of a hidden syn- 

 thesis, so that if we could penetrate more deeply into the sphere of 

 mental differentials, for instance, to differentials of the second or 



