382 METHODOLOGY OF SCIENCE 



from the inductive fundamental form of all hypothesis construction, 

 and correspond essentially to what we have called general or heuristic 

 hypotheses. His determination of the validity of these postulates, 

 however, implies the position to be assigned to the causal law and 

 therefore not to those heuristic hypotheses. " The postulate is not an 

 assumption that we can make or refrain from making, or. again, in 

 whose place we can substitute another. It is rather an (absolutely) 

 necessary assumption without which the content of the view at 

 issue would contradict the laws of our thought." 1 



Still the decision that we have reached is not on this account in 

 favor of rationalism, as this is represented for instance by Kant and 

 his successors down to our own time, and professed by Lotze in the 

 passage quoted, when he speaks of an absolute necessity for thought. 

 We found that the causal law requires a necessary connection be- 

 tween events given us in constant sequence. It is not, however, 

 on that account a law of our thought or of a "pure understanding" 

 which would be absolutely independent of all experience. When we 

 take into consideration the evolution of the organic world of which 

 we are members, then we must say that our intellect, that is, our 

 ideation and with it our sense perception, has evolved in us in ac- 

 cordance with the influences to which we have been subjected. The 

 common elements in the different contents of perception which have 

 arisen out of other psychical elements, seemingly first in the brute 

 world, are not only an occasion, but also an efficient cause, for the 

 evolution of our processes of reproduction, in which our memory 

 and imagination as well as our knowledge and thought, psycholog- 

 ically considered, come to pass. The causal law, which the critical 

 analysis of the material-scientific methods shows to be a funda- 

 mental condition of empirical thought, in its requirement that the 

 events stand as causes and effects in necessary connection, or real 

 dependence, comprehends these uniform contents of perception 

 only in the way peculiar to our thought. 



Doubtless our thought gives a connection to experience through 

 this its requirement which experience of itself could not offer. The 

 necessary connection of effect with cause, or the real dependence of 

 the former upon the latter, is not a component of possible percep- 

 tion. This requirement of our thought does not, however, become 

 thereby independent of the perceptive elements in the presupposi- 

 tions involved in the uniformity of sequence. The a priori in the 

 sense of "innate ideas," denoting either these themselves or an ab- 

 solutely a priori conformity to law that underlies them, for instance, 

 our "spontaneity," presupposes in principle that our "soul" is an 

 independently existing substance in the traditional metaphysical 

 sense down to the time of Locke. Kant's rationalistic successors, 

 1 Logic, 1874, buch n, kap. viii. 





