PRESIDENTIAL ADDRESS. 317 



inspired. Let us by all means welcome hypothesis, memory, inspiration, and 

 accident whenever and wherever they will help us : but they may fail, and then 

 our only resource is to help ourselves by the unfailing method of examining all 

 possibilities. The .aid of the others is adventitious and comes, like that of the 

 gods, most readily to those who help themselves. 



The maxim of 'leaving no stone unturned' was enunciated from a rather 

 different point of view some dozen years ago by an American geologist, Professor 

 T. C. Chamberlin, of Chicago, in a short paper for students entitled ' The 

 Method of Multiple Working Hypotheses.' After recalling how much the march 

 of science in early days was retarded by the tyranny of a theory formulated too 

 hastily, and how in later times attempts have been made to remedy this evil by 

 holding the theory, provisionally only, as a working hypothesis, Professor Cham- 

 berlin points out that even the working hypothesis has serious disadvantages : — 



Instinctively there is a special searching-out of phenomena that support 

 it, for the mind is led by its desires. . . . From an unduly favoured child 

 it readily grows to be a master and leads its author whithersoever it will. 

 . . . Unless the theory happens perchance to be the true one, all hope of 

 the best results is gone. To be sure truth may be brought forth by an in- 

 vestigator dominated by a false ruling idea. His very errors may indeed 

 stimulate investigation on the part of others. But the condition is scarcely 

 the less unfortunate. 



To avoid this grave danger the method of multiple working hypotheses 

 is urged. It differs from the simple working hypothesis in that it distri- 

 butes the effort and divides the affections. ... In developing the multiple 

 hypotheses, the effort is to bring up into view every rational explanation of 

 the phenomenon in hand and to develop every tenable hypothesis as to its 

 nature, cause, or origin, and to give all of these as impartially as possible 

 a working form and a due place in the investigation. The investigator thus 

 becomes the parent of a family of hypotheses : and by his parental 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. 



For the further elucidation of Professor Chamberlin's proposals I must refer 

 my audience to his original paper, which is well worthy of careful attention. He 

 does not shirk consideration of the drawbacks — ' No good thing is without its 

 drawbacks,' he writes. And it may be added that no good thing is entirely new, 

 or entirely old. Perhaps it is better to say that it is generally both new 

 and old. The Method of Multiple Hypotheses is new because it is still neces- 

 sary to remind scientific workers of all kinds that so long as they restrict them- 

 selves to the examination of one hypothesis only they can never reach complete 

 logical proof : they can only attain a high measure of probability. What is often 

 called verification 7 is not complete proof, but only increase in probability : for 



6 University of Chicago Press, 1897. 



7 To show that the facts agree with the consequences of our hypothesis is not 

 to prove it true. To show that is often called verification : and to mistake verifi- 

 cation for proof is to commit the fallacy of the consequent, the fallacy of think- 

 ing that, because, if the hypothesis were true, certain facts would follow, there- 

 fore, since those facts are found, the hypothesis is true. ... A theory whose 

 consequences conflict with the facts cannot be true ; but so long as there, may 

 be more than one giving the same consequences, the agreement of the facts with 

 one of them furnishes no ground for choosing between it and the others. Never- 

 theless in practice we often have to be content with verification ; or to take our 

 inability to find any other equally satisfactory theory as equivalent to there 

 being none other. In such matters we must consider what is called the weight 

 of the evidence for a theory which is not rigorously proved. But no one has 

 shown how weight of evidence can be mechanically estimated; the wisest men, 

 and best acquainted with the matter in hand, are oftenest right. — An Introduc- 

 tion to Logic, by H. W. B. Joseph, Fellow and Tutor of New College, Oxford. 

 Clarendon 'Press, 1906, p. 486, 



