80 WHAT IS SCIENCE? 



any more general laws. If it were found possible to 

 include all scientific laws as particular instances of one 

 extremely general and universal law, then, according 

 to this opinion, the purpose of science would be com- 

 pletely achieved. 



I dissent altogether from this opinion ; I think it leads 

 to a neglect of the most important part of science and to 

 a complete failure to understand its aims and develop- 

 ment. I do not believe that laws can ever be explained 

 by inclusion in more general laws ; and I hold that, even 

 it were possible so to explain them, the explanation would 

 not be that which science, developing the tendencies 

 of common sense, demands. 



The first point is rather abstruse and will be dismissed 

 briefly. It certainly seems at first sight that some laws 

 can be expressed as particular instances of more general 

 laws. Thus the law (stating one of the properties of 

 hydrogen) that hydrogen expands when heated seems 

 to be a particular instance, of the more general law, 

 that all gases expand when heated. I think this appear- 

 ance is merely due to a failure to state the laws quite 

 fully and accurately, and that if we were forced to state 

 with the utmost precision what we mean to assert by a law, 

 we should find that one of the laws was not a particular 

 case of the other. However, I do not wish to press this 

 contention, for it will probably be agreed that, even if 

 we have here a reference of a less general, to a more 

 general law, we have no explanation. To say that all 

 gases expand when heated is not to explain why hydrogen 

 expands when heated ; it merely leads us to ask immedi- 

 ately why all gases expand. An explanation which leads 

 immediately to another question of the same kind is no 

 explanation at all. 



