220 University of California Publications in Geology [Vol. S 



ore deposits, and an advocacy of a third. This hypothesis, so ably 

 championed by my distinguished critic, has become the favorite of 

 most recent writers on the subject, whether they describe particular 

 occurrences or discuss the general question. It invokes juvenile or 

 magmatic waters, emanating directly from molten magmas, as the 

 agency whereby ores have been deposited in or near intrusive masses. 

 In the literature of the day almost every deposit of ore that is found 

 to be in any way connected with igneous rocks is triumphantly 

 explained as an exemplification of the operation of this process. So 

 general has been the acceptance of the hypothesis that it has acquired 

 a curious air of finality. It seems to have escaped the ordeal of 

 criticism to which every scientific hypothesis should be subjected, not 

 only by the skeptics but also by those who believe in its probable truth. 

 The hypothesis is today being taught as a doctrine in texts and in 

 lectures to the students of geology throughout the United States with 

 as much certainty and as little question as was the doctrine of the 

 metamorphic origin of the Archean granites thirty years ago. Many 

 of its advocates appear to be more concerned with securing its general 

 acceptance by the coming generation of geologists than with sifting 

 out the evidence upon which it is based ; the special pleading of the 

 lawyer has been substituted for the dispassionate consideration of the 

 adverse evidence as well as the favorable — for the weighing of counter- 

 hypotheses which is the essence of scientific method. In itself the 

 notion that magmatic waters deposit ores is fascinating and plausible, 

 and the fact that so many eminent writers have been captivated by 

 it is, of course, indicative of its strength as compared with other 

 hypotheses that may be suggested to explain the same phenomena. 

 Should it after discussion and criticism become a scientifically estab- 

 lished theory to the exclusion of other hypotheses, it will undoubtedly 

 rank high among the achievements of geological science ; and those 

 who criticise it in its formative stage will have contributed not less 

 to its establishment than those who advocate its acceptance without 

 criticism. But the fact that an hypothesis is fascinating and plausible, 

 that there is much to be said in its favor, and particularly that eminent 

 geologists teach it, does not make it a scientifically established theory. 

 Skepticism must perform its function and exhaust itself before that 

 comes to pass. Competitive hypotheses must be exploited. To close 

 our eyes to them is to sacrifice our intellectual integrity. To dogmati- 

 cally deny them is to substitute for the method of science that of the 

 church. 



