384 THE POPULAR SCIENCE MONTHLY. 



the popular mode of apprehension is distinguished from the scien- 

 tific in being a compound of experience and metaphysics, and we 

 have here such an instance. But his own clear and guarded 

 statement is as follows : 



That we feel this immediately seems to be contradicted by the want of 

 agreement as to the existence of a mind distinct from the body, and by the fact 

 that it is only indirectly that we have come to know with which part of the body 

 the mind is more particularly connected. We can not maintain that the bodily 

 process causes the mental process, hecause the bodily process (the state of brain 

 connected with sensation) does not itself become an object of consciousness. And 

 if physiology could give a scientific explanation of the condition of the brain that 

 ensues when I am struck by a stone, the feeling of pain aroused in me would not 

 be included in the physiological explanation. Physiology explains a material pro- 

 cess by means of other material processes. Its assumptions can not include a case 

 in which one member of the causal relation shall be spatial and the other non- 

 spatial. 



Nor does the doctrine of the persistence of energy support the 

 idea of a causal relation between the mental and material. " The 

 doctrine of the persistence of energy is a purely physical doctrine. 

 Such an extension would imply the possibility of finding a com- 

 mon measure for the mental and material. Now, what denomi- 

 nator is common to a thought and a material movement, or what 

 common form serves for both ? Until such a common form can 

 be pointed out, all talk about an interaction between the mental 

 and material is, from a scientific point of view, unjustified. So 

 long as we confine ourselves to the material we are on safe 

 ground, and so long as we confine ourselves to the mental we are 

 on safe ground ; but any attempt to represent a transition from 

 physical to psychological laws, or conversely, brings us face to face 

 with the inconceivable. The causal concept can not be employed 

 to connect two factors which have no common measure. Again : 



"If the relation between mind and body, or consciousness and brain, is a 

 causal relation, there must be a difference of time between the process in the 

 brain and the act of consciousness. This, however, is contrary to the view sug- 

 gested by physiology. The aim of modern physiology is to conceive all organic 

 processes as physical or chemical. "Where it has attained to a comprehension of 

 anything in the region of organic life, this has in every case been by the tracing 

 back of organic phenomena to physical and chemical laws. If, then, there is a 

 transition from physiological function to psychological activity, from body to 

 mind, physiology, at any rate, working with its present method, can not discover 

 it. . . . So far as we can speak of final results in the physiology of the brain, it is 

 represented as a republic of nerve-centers, each with its function and all in inter- 

 action ; but there is nothing to indicate the possibility of the physiological proces3 

 breaking off at any point to pass into a process of a wholly different kind." But 

 in framing our hypotheses we may not enter into conflict with leading scientific 

 principles. " And, in modern natural science, the doctrine of energy is such a 

 leading principle. If, therefore, an hypothesis is in conflict with such a doctrine, 

 the fact tells at once decidedly against it." 



