HOFFDING'S OUTLINES OF PSYCHOLOGY. 385 



Here follows a brief account of the doctrine of interaction as 

 it appeared in the writings of Descartes, who, it is said, gave clear 

 and distinct form to the current doctrine which helped greatly to 

 lay bare its weak points. " To Descartes, therefore, belongs the 

 credit of having set the problem of the relation of mind and body. 

 For to the current notion in its vaguer form there is no difficulty 

 in this relation. With legitimate heedlessness, the practical usage 

 of speech ignores theoretical difficulties. Ordinary language no 

 more regards the fact that physiology and psychology are opposed 

 to the notion of brain and consciousness acting on one another 

 than it respects the doubt of Copernicus as to the sun really mov- 

 ing round the earth. Moreover, the practical usage of speech has 

 been formed under the influence of a partly spiritualistic, partly 

 materialistic metaphysics." 



Materialism. The case is made clearer when one of these two 

 factors is, without more ado, struck out. 



And since the perception of the external material world takes the leading 

 part in our ordinary ideas, while our inner self-consciousness is with difficulty 

 educated to a like clearness and distinctness, it is perhaps the most natural thing 

 to identify materiality with reality, and to conceive of the mental as an effect of 

 the material. Modern materialism usually treats the mental as a function of the 

 material. It has found a solid basis in the doctrine of the persistence of matter 

 and energy and in that of physiological continuity. As a method of natural science 

 it is unanswerable. But it is another affair when the method is converted into a 

 system. It has a perfect right to treat all changes and functions of the organism, 

 and in particular of the brain, as material ; but it goes further when it maintains 

 that the phenomena of consciousness are only changes and functions of the brain, 

 and in this consists its encroachment. 



Prof. Hoffding alludes to the position of Carl Vogt, who in 

 his time gave great offense by declaring that "as contraction 

 is the function of muscles, and as the kidneys secrete urine, so, 

 and in the same way, does the "brain generate thoughts, move- 

 ments, and feelings." In Vogt's comparison, " doubtless the chief 

 emphasis is to be laid on the secreting activity and not on the 

 product. The principle, however, remains the same. Among 

 cautious physiologists with some philosophical training, the doc- 

 trine that conscious activity is a function of the brain may be 

 sometimes met with." But the strict physiological use of the 

 term function must contradict such a doctrine. To say that con- 

 traction is the function of the muscle, only means that it is a cer- 

 tain form and a certain condition of the muscle in movement. It 

 is just as material when functioning as when at rest. The con- 

 ception function (in the physiological sense) implies, just as much 

 as the conception matter or product, something presented as an 

 object of intuition in the form of space. But thought and feeling 

 can not be pictured as objects in space, or as movements ; we get 



VOL. XXXIX. 27 



