64 ETHICAL ASPECTS OF EVOLUTION 



processes was indiscriminate ; but, as pleasure acts as a rein 

 forcement to the process to which it is attached, it follows 

 that those animals in which the noxious processes are 

 endowed with this additional strength disappear, and only 

 those remain in which noxious processes are dissociated 

 from pleasure. Similarly, pain acts as a clog : if, therefore, 

 advantageous processes are associated with pain, they will 

 be enfeebled, and the animal will be crippled in the compe 

 tition with those in which the same class of processes are 

 strengthened by pleasure. We begin, in fact, with a cross- 

 division with two pairs of opposites, pleasure and pain, 

 advantage and disadvantage ; and a tendency to reduce this 

 cross-division to a single division, in which the two first 

 terms of each of the original pairs of opposites will be on 

 one side, and the second terms on the other. The degree 

 to which this reduction has been carried out will serve as 

 an index of the grade of evolution which any particular 

 animal occupies. 



All that concerns us at present in this theory is that, 

 true or not, it at any rate does not identify pleasure with 

 advantage, and, instead of affirming, it contradicts the 

 possibility of defining one in terms of the other. What it 

 amounts to is a prophecy that, in some remote future, that 

 identification may be brought about. But what we require 

 is a definition of pleasure and pain as we know them at 

 present, and prophecies, however well inspired, are of no 

 value. Nor does it help us in striking the present balance 

 between pleasure and pain. To discover that, we must 

 find out what stage we have reached between the beginning 

 and the end of the long journey of evolution ; and the only 

 way of finding out what stage we have reached is to ascertain 

 the degree in which pleasure predominates over pain. We 

 are, in fact, exactly where we started, and have nothing 

 better to go on than the rough enumeration with whose 

 defects the earlier pages of this note were occupied. 



This theory, again, makes no allowance for the principles 

 of excess and inhibition, which are both more highly de 

 veloped in the human race than in any other grade of life. 



