476 THE POPULAR SCIENCE MONTHLY. 



spectrum many lines coincident in position with those which these 

 metals would produce ; and this hypothesis is greatly strengthened by 

 our knowledge of the remarkable distinctiveness of the particular line 

 of characters observed. But such a fortification of hypothesis is of a 

 deductive kind, and hypothesis may still be probable when such rein- 

 forcement is wanting. 



There is no greater nor more frequent mistake in practical logic than 

 to suppose that things which resemble one another strongly in some 

 respects are any the more likely for that to be alike in others. That 

 this is absolutely false, admits of rigid demonstration ; but, inasmuch 

 as the reasoning is somewhat severe and complicated (requiring, like 

 all such reasoning, the use of A, B, C, etc., to set it forth), the reader 

 would probably find it distasteful, and I omit it. An example, however, 

 may illustrate the proposition : The comparative mythologists occupy 

 themselves with finding points of resemblance between solar phenom- 

 ena and the careers of the heroes of all sorts of traditional stories ; and 

 upon the basis of such resemblances they infer that these heroes are 

 impersonations of the sun. If there be anything more in their reason- 

 ings, it has never been made clear to me. An ingenious logician, to 

 show how futile all that is, wrote a little book, in which he pretended 

 to prove, in the same manner, that Napoleon Bonaparte is only an im- 

 personation of the sun. It was really wonderful to see how many points 

 of resemblance he made out. The truth is, that any two things resem- 

 ble one another just as strongly as any two others, if recondite resem- 

 blances are admitted. But, in order that the process of making an hy- 

 pothesis should lead to a probable result, the following rules must be 

 followed : 



1. The hypothesis should be distinctly put as a question, before 

 making the observations which are to test its truth. In other words, 

 we must try to see what the result of predictions from the hypothesis 

 will be. 



2. The respect in regard to which the resemblances are noted must 

 be taken at random. We must not take a particular kind of predictions 

 for which the hypothesis is known to be good. 



3. The failures as well as the successes of the predictions must be 

 honestly noted. The whole proceeding must be fair and unbiased. 



Some persons fancy that bias and counter-bias are favorable to the 

 extraction of truth that hot and partisan debate is the way to investi- 

 gate. This is the theory of our atrocious legal procedure. But Logic 

 puts its heel upon this suggestion. It irrefragably demonstrates that 

 knowledge can only be furthered by the real desire for it, and that the 

 methods of obstinacy, of authority, and every mode of trying to reach 

 a foregone conclusion, are absolutely of no value. These things are 

 proved. The reader is at liberty to think so or not as long as the proof 

 is not set forth, or as long as he refrains from examining it. Just so, 

 he can preserve, if he likes, his freedom of opinion in regard to the 



