98 THE LIMITATIONS OF SCIENCE 



mentally. Besides our thesis is with such methods in 

 general, and in this respect only is a study of Des- 

 cartes's system useful, as it is his method which still 

 flourishes in the theories of physics and of other sci- 

 ences. He is to be admired in this respect; when 

 he had once outlined his premises and his method, he 

 deduced his conclusions as rigorously as possible, and 

 compared them consistently with experience; whereas 

 it has become the custom now to alter postulates when- 

 ever their conclusions point to error, with the result 

 that it is most difficult to outline a consistent and in- 

 vidual modern theory. If we study modern scientific 

 theories we find that the postulates are as metaphysical, 

 if not more so, than those of Descartes. They are 

 stated with much assurance, but as the conclusions un- 

 fold themselves, we begin to notice a certain hesitation 

 and a desire to limit the discussion to a small and re- 

 lated class of phenomena. Or if an excursion is made 

 into a wider field, lack of confidence increases and usu- 

 ally results in a modification and confusion of the 

 postulates. If Descartes's theory may be illustrated as 

 a tree with all its conclusions branching out from a 

 single idea as a stem, our present state of physics is 

 like a thicket of bushes with many stems so concealed 

 and interwoven that the parent stem of any branch 

 cannot be distinguished. 



I have sketched the most elaborate and comprehen- 

 sive hypothesis ever developed in the name of science, 



