70 POPULAR SCIENCE MONTHLY. 



form every tenable hypothesis of its nature, cause or origin, and to 

 give to each of these a due place in the inquiry. The investigator 

 thus becomes the parent of a family of hypotheses; and by his paternal 

 relations to all is morally forbidden to fasten his affections unduly 

 upon any one. In the very nature of the case, the chief danger that 

 springs from affection is counteracted. Where some of the hypotheses 

 have been already proposed and used, while others are the investiga- 

 tor's own creation, a natural tendency to bias arises, but the right use 

 of the method requires the impartial adoption of all into the working 

 family. The investigator thus at the outset puts himself in cordial 

 sympathy and in the parental relations of adoption, if not of author- 

 ship, with every hypothesis that is at all applicable to the case under 

 investigation. Having thus neutralized, so far as may be, the partiali- 

 ties of his emotional nature, he proceeds with a certain natural and 

 enforced erectness of mental attitude to the inquiry, knowing well that 

 some of the family of hypotheses must needs perish in the ordeal of 

 crucial research, but with a reasonable expectation that more than one 

 of them may survive, since it often proves in the end that several 

 agencies were conjoined in the production of the phenomenon. Hon- 

 ors must often be divided between hypotheses. In following a single 

 hypothesis, the mind is biased by the presumptions of the method to- 

 ward a single explanatory conception. But an adequate explanation 

 often involves the coordination of several causes. This is especially 

 true when the research deals with complicated phenomena such as 

 prevail in the field of the earth-sciences. Not only do several agencies 

 often participate, but their proportions and relative importance vary 

 from instance to instance in the same class of phenomena. The true 

 explanation is therefore necessarily multiple, and often involves an 

 estimate of the measure of participation of each factor. For this the 

 simultaneous use of a full staff of working hypotheses is demanded. 

 The method of the single working hypothesis is here incompetent. 



The reaction of one hypothesis upon another leads to a fuller and 

 sharper recognition of the scope of each. Every added hypothesis is 

 quite sure to call forth into clear recognition neglected aspects of the 

 phenomena. The mutual conflicts of hypotheses whet the discrimi- 

 native edge of each. The sharp competition of hypotheses provokes 

 keenness in the analytic processes and acuteness in differentiating 

 criteria. Fertility in investigative devices is a natural sequence. If 

 therefore an ample group of hypotheses encompass the subject on all 

 sides, the total outcome of observation, of discrimination and of recog- 

 nition of significance and relationship is full and rich. 



Closely allied to the method of multiple working hypotheses is 



The Method of Multiple Series. 

 In many of the more complex problems of the earth-sciences the 

 basal facts are but imperfectly determined, e. g., the rate of rise of 



