444 SCIENCE PROGRESS 



parently never has been answered and since many people 

 interpret silence as inability to reply, it is desirable to make a 

 few obvious criticisms. 



The method is that which is sometimes called per exclusionem. 

 The first stage is to prove that there are only a limited number 

 of possible explanations of some phenomenon. The second stage 

 is to prove in turn that all these explanations except one are 

 false. It then follows that that one must be true. Fallacies 

 may enter at any step in the argument ; but they are most likely 

 to occur in the first stage. It must always be an exceedingly 

 difficult matter to prove that the range of possible explanations 

 is limited to four or five or any other number. It is difficult 

 to imagine a process by which one could make sure that no 

 alternative possibility had been overlooked : that all conceiv- 

 able theories have been marshalled in the field and that the 

 suggestion of any other theory at any future time in the history 

 of science is inconceivable. Yet, unless that be done, the whole 

 method lapses. The second stage presents a further oppor- 

 tunity for the introduction of fallacies. Each suggested ex- 

 planation that is refuted furnishes a loophole for error in the 

 refutation ; and a single error at any part of the argument 

 vitiates the whole. It is obvious, therefore, how untrustworthy 

 and difficult the method per exclusionem must always be. Has 

 Driesch recognised that untrustworthiness ? I have already 

 observed that he takes ten pages to dismiss the three possible 

 explanations which he suggests; that is, for the second stage. 

 But he has clean forgotten all about the first stage. The reader is 

 left in bewilderment to work out for himself why there should 

 only be four possible explanations of development ! Can I 

 suggest another? I may be asked. The question is irrelevant. 

 It should be: Is it inconceivable that in the future history of 

 mankind any fifth alternative will ever be put forward? And 

 to this there is surely only one imaginable answer : It is not 

 inconceivable. 



In view of the hopeless instability of the foundations of 

 Driesch's argument, it would be a waste of time to insist on 

 the inadequacy of his refutations of the three alternatives so 

 summarily rejected. Let us move on to the fourth explanation, 

 "entelechy," which is left victorious in the field. I have called 

 it an explanation : though, so far from explaining anything, it 

 appears to me far more mystifying than the original problem. 



