No. 588] SHORTER ARTICLES AND DISCUSSION 



7G7 



Ein zur Erklarung bestimmter Wahrnehmungen ersonnener Factor 

 von dem eine derartige Annahme d. h. ein Zustand der Nichtbetatigung 

 widersinnig ware mag folgeriehtig als " nieht materiell " bezeiehnet 



Neither Jennings's " non-perceptual" or my "immaterial" 

 can be considered an illogical or contradictory conception. 

 Criticism must, so far as my own doctrine is concerned, be there- 

 fore concentrated solely on the strength of the empirical founda- 

 tion for the hypothesis of immaterial factors in any given case. 



Besides the logical definition given above, an examination is 

 required of the question ; What exactly can be meant by, or how 

 can one be led to assume, an "immaterial factor" as a result of 

 experimental investigation, or at least as a hypothesis impelled 

 by such a result? 



To Jennings the assumption of a "non-perceptual agent" 

 leads directly to, or is synonymous with, the so-called "experi- 

 mental indeterminism, " as admitted by Driesch. 



He seems to neglect every other possibility of the action of an 

 "immaterial factor." I do not see that this is inevitable. 



To me the essential point of the problem lies in the question 

 of the "bearers" for any sort of empirically detectible action 

 (induction, force, or the like). 



Suppose that it were found that the factors directing the 

 movements of a given element of a living organism (for example, 

 the cell of an embryo), in a given direction m to the point n, lie 

 outside itself. 



"We will then assume at the point n a center of forces. 



Suppose now that we can deduce from this assumption certain 

 consequences that will be subsequently verified empirically. 8 

 Our assumption that gives us possibilities of prediction becomes 

 then a scientific reality. We say "reality," although it may 

 remain somewhat hypothetical. We find the same condition of 

 affairs in the imperceptible but strongly inferred realities of 

 physics, etc. 



si find that there is a point at which Jennings's conception of the "non- 

 perceptual" seems to lead us wrong. It is well to say with Jennings that 

 such an agent is one producing at a particular time a particular physical 

 event but not subject to other physical tests for its presence (italics mine). 

 But Jennings seems not to take into consideration that a "particular phys- 

 ical event" or a "single mode of action" (in my formulation) can lead to 

 many empirically verifiable consequences. 



