46 INTRODUCTION TO SCIENCE 



More briefly, causation in the current scientific 

 sense means sequence under definitely known 

 conditions." 



This view of cause and effect as earlier and 

 later stages of the same continuous process, 

 unified by a pervading principle, brings us back 

 to the "descriptive" ideal of scientific explana- 

 tion. "According to this doctrine, advocated 

 by such eminent thinkers as Kirchhoff, Mach, 

 and Ostwald among physicists, and, with various 

 modifications, Avenarius, Miinsterberg, Royce, 

 and James Ward among recent philosophers, the 

 ultimate ideal of science, or at any rate of physi- 

 cal science, is simply the description of the course 

 of events by the aid of the fewest and simplest 

 general formulae. Why things happen as they 

 do, it is now said, is no proper question for science; 

 its sole business is to enable us to calculate how 

 they happen." 



REDUCTION TO SIMPLER TERMS. It is the 

 continual aim of science to reduce the number 

 of categories or necessary concepts. This is 

 the art of wielding William of Occam's razor 

 "Entia non sunt multiplicanda praeter necessi- 

 tatem." "Entities are not to be multiplied be- 

 yond necessity." Of the effort to reduce the 

 categories let us take a famous illustration. On 

 the occasion of his jubilee (1896) as Professor of 

 Natural Philosophy, Lord Kelvin, then a veteran 



