therefore inferable from it ; are believable because based upon evidence 

 which can be repeatedly tested, and because the things implied to exist 

 out of experience are like things in experience and therefore compre- 

 hensible to us; and, finally, useful because verifiable, believable, and 

 applicable to situations in our experience. 



If then our investigation has been based upon typical examples of 

 methods of thinking and has been sufficiently thorough, we can warn 

 the thinker against the method of assumption and deduction which gives 

 rise to unbelievable and useless theories, and recommend to him the 

 method of experiment and inference, which yields a theory believ- 

 able and of practical value. 



We have from this study of methods of thinking, arrived at 

 conclusions concerning the qualities of theories and the relative 

 merits of the methods by which they were derived. With that our 

 investigation is concluded. 



However, another problem, closely related to the one consid- 

 ered, has occurred to the writer, and although a solution of it would 

 require other material and a much wider research than has been here 

 presented, yet a statement of the problem may be of value. 



We may safely consider that each thinker who presents a 

 theory to the world for its sanction, has faith in his own method of 

 thinking, and in the conclusions at which he has arrived. What 

 differences are there in the mental make-up of thinkers, which will 

 account for such diverse methods of thinking and for such diverse 

 susceptibilities to belief in different kinds of theories? Three of the 

 theories which we studied were concerned with the nature of matter, 

 one with the nature of organic life, one with the nature of knowl- 

 edge, and one with the existence of life after death. Was it the 

 problem which determined the method of thinking? Would Dar- 

 win have reasoned as Hyslop did, had he dealt with the question of 

 life after death? Or, had Norman Lockyer have dealt with the 

 question of the nature of knowledge, would he have proceeded as 

 Locke did and have been satisfied with Locke's conclusions? We 

 have determined that the methods used by Darwin and Lockyer 

 were applicable to the problems treated by Hyslop and Locke and 

 vice versa ; yet Darwin and Lockyer applied one method, and Locke 

 and Hyslop another, and each apparently felt that his method was 

 the natural, ready and secure methods of reaching the truth. 



Men have been roughly classified into thinking, willing and 

 feeling men, according as the propensity for thinking, willing or feel- 

 ing predominated. Will these broad differences in mental tendency 

 account for the different manners in which men theorize? Can we 

 say that Hyslop believes in his conclusions, which have slight foun- 



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