18 MENTAL EVOLUTION IN ANIMALS. 



of a machine under the manipulations of an operator : when 

 certain springs of action are touched by certain stimuli, the 

 whole machine is thrown into appropriate action ; there is no 

 room for choice, there is no room for uncertainty ; but, as 

 surely as any of these inherited mechanisms is affected by 

 the stimulus with reference to which it has been constructed 

 to act, so surely will it act in precisely the same way as it 

 always has acted. But the case with conscious mental adjust- 

 ment is quite different. For, without going into the question 

 concerning the relation of Body and Mind, or waiting to ask 

 whether cases of mental adjustment are not really quite as 

 mechanical in the sense of being the necessary result or 

 correlative of a chain of psychical sequences due to a physical 

 stimulation, it is enough to point to the variable and incalcu- 

 lable character of mental adjustments as distinguished from 

 the constant and foreseeable character of reflex adjustments. 

 All, in fact, that in an objective sense we can mean by a 

 mental adjustment, is an adjustment of a kind that has not 

 been definitely fixed by heredity as the only adjustment 

 possible in the given circumstances of stimulation. Tor, were 

 there no alternative of adjustment, the case, in an animal at 

 least, would be indistinguishable from one of reflex action. 



It is, then, adaptive action by a living organism in cases 

 where the inherited machinery of the nervous system does 

 not furnish data for our prevision of what the adaptive action 

 must necessarily be — it is only in such cases that we recog- 

 nize the element of mind. In other words, ejectively con- 

 sidered, the distinctive element of mind is consciousness, the 

 test of consciousness is the presence of choice, and the 

 evidence of choice is the antecedent uncertainty of adjustive 

 action between two or more alternatives. To this analysis it 

 is, however, needful to add that, although our only criterion 

 of mind is antecedent uncertainty of adjustive action, it does 

 not follow that all adjustive action in which mind is con- 

 cerned should be of an antecedently uncertain character ; or, 

 which is the same thing, that because some such action may 

 be of an antecedently certain character, we should on this 

 account regard it as non -mental. Many adjustive actions 

 which we recognize as mental are, nevertheless, seen before- 

 hand to be, under the given circumstances, inevitable ; but 

 analysis would show that such is only the case when we have 

 in view agents whom we already, and from independent 

 evidence, regard as mental. 



