THEOKIES OF MENTAL EVOLUTION 265 



and, therefore, by the will. They differ from rational actions 

 in that the capacity to feel the instinctive desire is always 

 inborn, as is also, as a rule, the capacity to perform the 

 instinctive action by which the desire is gratified ; l whereas 

 the capacity to feel the " rational " desire and the ability to 

 gratify it are always acquired. On the other hand, reflexes 

 resemble instincts in that they develop in the individual 

 under the influence of the same class of stimuli (nutrition, 

 etc.); they differ from instincts in that they are not dis- 

 charged by the same class of stimuli that is, they are not 

 discharged by desires acting through the will. 



429. Professor James insists that all actions in man are 

 originally reflex. But, if the foot of a child of two be 

 pinched, it is snatched away. The newborn baby, similarly 

 maltreated, merely shrieks. Clearly the action of the elder 

 child is not reflex, though it may be automatic, for the 

 capacity to co-ordinate the muscles for its performance has 

 been acquired. The shriek of the baby, if our definitions are 

 correct, is instinctive, not reflex. It is prompted by pain. 

 It is reflex only in the sense that any rational action is 

 reflex. 



430. In defining reflex actions as purely involuntary, and 

 instinctive and " rational " actions as purely voluntary, we 

 have sharply marked off the former from the latter. Simi- 

 larly, by showing that instinct arises in the individual under 

 one kind of stimulus, and reason under quite another kind 

 of stimulus, we have sharply separated instinct from reason, 

 leaving no border space where the one merges into the other. 

 Throughout we have proceeded on the assumption that 

 all these faculties have arisen solely through the Natural 

 Selection of favourable spontaneous variations. We have 

 supposed, also, that reflex action, strictly so called, 2 appeared 

 when the nervous system had reached a somewhat advanced 

 stage of evolution ; that later, at a stage still more advanced, 

 instinct appeared ; and that yet later, at a stage even more 

 advanced, reason appeared ; the three faculties not being 

 derived the one from the others, but appearing like branches 

 on a common stem. 



431. Until recently, however, psychologists, who treated 

 the subject from the standpoint of evolution, believed in 

 the transmission of acquirements and derived the faculties 



1 The capacity to perform the instinctive action is not always inborn. 

 Thus a man cannot gratify his sporting and sexual instincts without the 

 aid of his acquired powers of co-ordinating his muscles. 



2 See 365. 



