INTRODUCTION. 5 



for it is impossible that heredity can have provided in 

 advance for innovations upon, or alterations of, its machi- 

 nery during the lifetime of a particular individual. 



In my next work I shall have occasion to consider this 

 criterion of mind more carefully, and then it will be 

 shown that as here stated the criterion is not rigidly ex- 

 clusive, either, on the one hand, of a possibly mental 

 element in apparently non-mental adjustments, or, con- 

 versely, of a possibly non-mental element in apparently 

 mental adjustments. But, nevertheless, the criterion is 

 the best that is available, and, as it will be found sufficient 

 for all the purposes of the present work, its more minute 

 analysis had better be deferred till I shall have to treat of 

 the probable evolution of mind from non-mental an- 

 tecedents. I may, however, here explain that in my use 

 of this criterion I shall always regard it as fixing only the 

 upper limit of non-mental action ; I shall never regard it 

 as fixing the lower limit of mental action. For it is clear 

 that long before mind has advanced sufficiently far in the 

 scale of development to become amenable to the test in 

 question, it has probably begun to dawn as nascent sub- 

 jectivity. In other words, because a lowly organised 

 animal does not learn by its own individual experience, 

 we may not therefore conclude that in performing its 

 natural or ancestral adaptations to appropriate stimuli 

 consciousness, or the mind-element, is wholly absent ; we 

 can only say that this element, if present, reveals no 

 evidence of the fact. But, on the other hand, if a lowly 

 organised animal does learn by its own individual experi- 

 ence, we are in possession of the best available evidence 

 of conscious memory leading to intentional adaptation. 

 Therefore our criterion applies to the upper limit of non- 

 mental action, not to the lower limit of mental. 



Of course to the sceptic this criterion may appear un- 

 satisfactory, since it depends, not on direct knowledge, 

 but on inference. Here, however, it seems enough to 

 point out, as already observed, that it is the best 

 criterion available ; and further, that scepticism of this 

 kind is logically bound to deny evidence of mind, not only 

 in the case of the lower animals, but also in that of the 



