THE PHILOSOPHICAL BASIS 27 



should be remarked that such a connection would 

 not show that mechanics is necessarily the more 

 fundamental science : it would be quite as correct, 

 when the connection is established, to express 

 mechanical quantities in terms of electricity or 

 temperature. 



This example leads us to state in a general 

 form the immediate object of Physical Science. 

 The physicist seeks to discover the relations 

 between different phenomena, considered in one 

 limited aspect, and to express those relations in 

 a definite quantitative way. Our minds, led by 

 the analogy with their own volitions, usually 

 think of one of the related phenomena as the 

 cause, and of the other as the effect. The 

 physical equation which expresses the dependence 

 of A on B, or, in symbols, A = f(B), may equally 

 well be written in the inverse form, by which B 

 is asserted to be a function of A. In such cases, 

 there is probably no philosophical distinction 

 between cause and effect ; it is no more rio^ht 

 to say that an increase of pressure produces a 

 decrease of volume in a gas than to say that 

 a decrease of volume produces an increase of 

 pressure. The student merely discovers by 

 experiment that the two phenomena accompany 

 each other in every case investigated, and sums 

 up the results of experience in conceptual language 

 and in a shorthand form, in order to save the 

 detailed investigation of each future individual 

 case. 



In these examples, the needlessness of the 

 ideas of cause and effect will be fairly clear, what- 

 ever may be thought about their metaphysical 

 importance. It is where the element of time is 



