98 MODES OF RESEARCH IN GENETICS 



of betting odds. It has no necessary relation 

 per se to any physical, chemical, or biological laws. 

 It merely informs one how he may safely gamble 

 on an event if he is so minded and can find some 

 one else ready to do the same thing. 



Wherein lies the value of the probable error 

 concept for science, then.^ Simply in that it 

 serves as a test or check on every mode of research 

 in science. So far as I can see, the calculus of 

 probability, in and of itself alone, is not and 

 never can be an effective weapon of research for 

 the discovery of truth in phenomenal science, be 

 it physical or biological. Yet it operates as an 

 ever-present test of the trustworthiness of the 

 results obtained by modes of research which are in 

 themselves adapted to making discoveries about 

 phenomena. The student of probability says 

 something like this to the experimentalist : "Yours 

 is the way to find out the significant underlying 

 causes of phenomena. Let it be practiced with 

 all zeal, but let it be remembered that you operate 

 in a finite way in a finite universe, and conse- 

 quently all your results are subject to such fluc- 

 tuations and variations as experience has shown 

 arise from random sampling. I regret that I 

 cannot directly and alone discover significant 

 causes, but at any rate I can furnish you a test 

 whereby you may reasonably judge whether your 

 result is significantly influenced by these fluctu- 

 ations of random sampling." 



