196 MYSTICISM AND LOGIC 



will be approximately the same in any two states of the 

 universe which only differ in regard to what is at a con- 

 siderable distance from the small volume in question. 

 For example, motions of planets in the solar system must 

 be approximately the same however the fixed stars may 

 be distributed, provided that all the fixed stars are very 

 much farther from the sun than the planets are. If 

 gravitation varied directly as the distance, so that the 

 most remote stars made the most difference to the 

 motions of the planets, the world might be just as regular 

 and just as much subject to mathematical laws as it is at 

 present, but we could never discover the fact. 



(4) Although the old " law of causality " is not assumed 

 by science, something which we may call the *' uniformity 

 of nature " is assumed, or rather is accepted on inductive 

 grounds. The uniformity of nature does not assert the 

 trivial principle " same cause, same effect,'* but the 

 principle of the permanence of laws. That is to say, 

 when a law exhibiting, e.g. an acceleration as a function 

 of the configuration has been found to hold throughout 

 the observable past, it is expected that it will continue 

 to hold in the future, or that, if it does not itself hold, 

 there is some other law, agreeing with th^ supposed law 

 as regards the past, which will hold for the future. The 

 ground of this principle is simply the inductive ground 

 that it has been found to be true in very many instances ; 

 hence the principle cannot be considered certain, but 

 only probable to a degree which cannot be accurately 

 estimated. 



The uniformity of nature, in the above sense, although 

 it is assumed in the practice of science, must not, in its 

 generahty, be regarded as a kind of major premiss, with- 

 out which all scientific reasoning would be in error. The 

 assumption thai all laws of nature are permanent has, of 



