THE RATIONALE OF PHILOSOPHICAL THOUGHT. 759 



sophic reasoning. This became more evident and more 

 popularly known through the writings of Mach in 

 Germany, of Clerk Maxwell, Clifford, and Karl Pearson 

 in England. The manner also in which Tait in his 

 popular Lectures and his polemics treated the notions 

 of " Matter " and " Force," showing that both could be 

 dispensed with in mechanical science, which could be 

 built up with the measurable quantities of time, space, 

 velocity, and inertia (capacity of motion), demonstrated 

 the futility of building up a satisfactory philosophy upon 

 the materialistic basis of Kraft unci Stoff. However, 

 the process of gradually eliminating the notions of 

 '' Vital Force," of " Force " and of " Matter " and " Sub- 

 stance " in the popular sense from the strict notation of 

 science, had not only a negative, it had also a positive 

 result : it led to various attempts to say what the mind 

 really means by the discarded terms " Force " and " Sub- 

 stance," a process of criticism after the manner of Lotze. 

 It gradually became clear that these terms, as well as 

 the term " Life," imply something non - mechanical, 

 denoting some psychical experience. 



The fact that none of the expounders of the mechani- 23. 



Inadequacy 



cal or naturalistic philosophy could dispense with one °£™?- , 



r r J 1- chanical 



or more of these terms was a proof that some other "^®^*- 

 than mechanical notions had to be covertly or surrepti- 

 tiously introduced in order to build up a reasoned creed. 

 Thus Herbert Spencer termed the underlying reality the 

 Unknowable Power, and the mechanical principle which 

 pervades the region of knowable things. Force ; and 

 Haeckel introduces the term " Substance." These three 

 terms are intelligible to the human mind only through 



