3IO A Limit to Evolution 



But again, some readers may feel tempted to exclaim that 

 certain animals are highly intelligent, and that very many 

 animals know their homes, their friends, and their enemies ; 

 that, therefore, animals ' know ' many things which we know, 

 and that though they have not the use of ' words,' yet never- 

 theless they must have ' ideas.' 



Now we should be sorry to deny the admirable and love- 

 able endowments of the animal world. A man must have a 

 very defective nature who does not love his faithful brute 

 companions. But we ought not to allow affection, any more 

 than hatred, to blind us and so mislead our judgment, and 

 in considering the higher faculties of such creatures as dogs 

 and monkeys, there are four rules which should ever be 

 borne carefully in mind. These are : — 



(1) To guard against the misleading tendency of our 

 emotions with regard to pet animals. Their owners are 

 constantly tempted to read into the actions of such animals 

 meanings for which there is no real evidence, and to mistake 

 imperfect influences, due to partiality, for real observations. 



(2) To guard against our besetting tendency to judge 

 everything by our own standard, and without reason to 

 imagine the existence of human qualities in things which are 

 not human. This is that error of undue anthropomorphism 

 against which the opponents of all rehgion so often warn us. 



(3) Not to suppose that unknown causes are acting, when 

 known causes are sufficient to account for all the facts 

 observed. This is that old well-known rule, called Occam's 

 razor : Entia non sunt multiplicanda prceter necessitatem. 



(4) To bear in mind that if any cause, did it exist, would 

 inevitably produce certain effects, we must not suppose 

 the existence of that cause, when such effects are not to be 

 discovered. 



Now, of course, animals have ' intelligence,' ' understand- 

 ing,' and ' knowledge ' in the loose sense in which those terms 



