MENTAL LIFE 



he was held back from this by the profound mystic 

 tendency of his theory of reason, and the dogma of the 

 immortahty of the soul, the freedom of the will, and the 

 categorical imperative. Reason remained in Kant's 

 view a transcendental phenomenon, and this dualistic 

 error had a great influence on the whole structure of his 

 philosophy. It must be remembered, of course, that 

 our knowledge of the psychology of peoples was then 

 very imperfect; but a critical study of the facts then 

 known should have sufficed to convince him of the lower 

 and animal condition of their minds. If Kant had had 

 children, and followed patiently the development of the 

 child's soul (as Preyer did a century later), he would 

 hardly have persisted in his erroneous idea that reason, 

 with its power of attaining a priori knowledge, is a 

 transcendental and supernatural wonder of life, or a 

 unique gift to man from Heaven. 



The root of the error is that Kant had no idea of the 

 natural evolution of the mind. He did not employ the 

 comparative and genetic methods to which we owe the 

 chief scientific achievements of the last half-century. 

 Kant and his followers, who confined themselves almost 

 exclusively to the introspective method or the self-obser- 

 vation of their own mind, regarded as the model of the 

 human soul the highly developed and versatile mind of 

 the philosopher, and disregarded altogether the lower 

 stages of mental life which we find in the child and the 

 savage. 



The immense advance made by the science of man 

 in the second half of the nineteenth century cut the 

 ground from under the older anthropology and the 

 dualistic system of Kant. A number of newly founded 

 branches of science co-operated in the work. Compara- 

 tive anatomy showed that our whole complicated frame 

 resembles that of the other mammals, and in particular 

 differs only by slight stages of growth, and therefore in 



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