2 4 o THE LIMITATIONS OF SCIENCE 



natural or to a natural force. The variation of species 

 may be due to a supernatural power which created a 

 protoplasm and then guided organic life through the 

 slow developing ages. But to us such a form of 

 creation is as little scientific as the cosmogony of the 

 Book of Genesis. Scientific hypotheses must avoid the 

 supernatural and, however they differ in details, they 

 must base evolution on the natural laws of probability 

 and chance, using these words in their technical sense 

 of expressing the statistical actions of physical, chem- 

 ical, or biological forces on molecular masses. In 

 natural or scientific law there can be assumed no escape 

 from the calculable action of a force. Given effects fol- 

 low from given causes and these must precede each 

 other with uniform regularity, back as far as we care 

 to carry the law. In this manner we have formulated 

 a law of evolution without introducing the idea of 

 ethics at all. And so far as the question concerns 

 ethics it is restricted to a minute province, man, in the 

 vast empire of life. Thus we have made an absolute 

 break in the law of evolution; on one side is the un- 

 moral development of all the universe, and on the other 

 side is the moral growth of man. At least in our 

 egotism we reserve the attribute of character, or of 

 judging actions as good or evil, to ourselves. It is 

 almost useless to add that a law of continuous develop- 

 ment, like evolution, with such a break in it is far from 

 perfect. 



