COMMON BASIS OF EMPIRICISM AND RATIONALISM 47 



only unaccomplished, but indefinitely exceeds human powers. 

 In the actual progress of his scientific work, the rationalist cannot 

 fail to verify the aphorism of Bacon: 'The syllogism is not ap- 

 plied to the first principles of science, and is applied in vain to 

 intermediate laws, being no match for the subtlety of nature." 1 

 Consider, for example, the testimony of Descartes: "Afterwards 

 when I wished to descend to the more particular, so many diverse 

 objects presented themselves to me, that I believed it to be im- 

 possible for the human mind to distinguish the forms or species 

 of bodies that are upon the earth, from an infinity of others which 

 might have been . . . unless we rise to causes through their effects, 

 and avail ourselves of many particular .experiments." In this 

 way, he says, he had never failed to find a satisfactory explanation 

 of any phenomenon, on the basis of his already deduced prin- 

 ciples. "But it is necessary also to confess that the power of 

 nature is so ample and vast, and these [already deduced] prin- 

 ciples so simple and general, that I have hardly observed a single 

 particular effect which I cannot at once recognize as capable of 

 being deduced in many different modes from the principles, and 

 that my greatest difficulty usually is to discover in which of these 

 modes the effect is dependent upon them; for out of this difficulty 

 I cannot otherwise extricate myself than by again seeking certain 

 experiments, which may be such that their result is not the same, 

 if it is in one of these modes that we must explain it, as it would 

 be if it were to be explained in the other." 2 Perhaps the most 

 significant feature of this confession is Descartes's embarrassment 

 at finding several possible explanations of a phenomenon. For 

 since explanation is deduction, a possible explanation is an actual 

 one and what geometrician was ever embarrassed by the dis- 

 covery of several proofs for a theorem, or of several solutions for 

 a problem? Such embarrassment can only mean that the alter- 

 native explanations depend upon anterior principles which are 

 mutually exclusive, but between which the investigator has not 

 yet been able to decide; or, to put the matter squarely, that an 



l Novum Organum, Book I, 13. 

 ^Discourse on Method, Part VI. 



