HYPOTHESIS 151 



If, finally, in our inquiry into the ultimate cause and explana 

 tion of experience as a whole, the relation between the supposed 

 cause and this experience be such that we can argue a posteriori 

 from the latter to the existence and nature of the former merely 

 in virtue of the principle of causality then our reasoning may 

 reach certitude, provided we are able to show that the facts con 

 sist with no other interpretation. This we consider to be the 

 case in regard to the philosophy of theism as an explanation of 

 the whole field of human experience. 



234. SOURCES OF SCIENTIFIC HYPOTHESES: ANALOGY. 

 In a general way, it may be asserted that all hypotheses have 

 their origin in observation of facts and reflection on what we al 

 ready know about facts. We may, however, distinguish a few 

 of the more important immediate sources of hypotheses. 



(i) Even reflection on the common class names and ordinary 

 generalizations embodied in the language we use, may raise prob 

 lems about the phenomena of experience, and suggest hypotheses 

 in explanation of them. All inquiry into the causes of things 

 presupposes, as its initial stage, the classification of similar things 

 on the basis of common attributes (63, 68), and the nomenclature 

 or system of class names or general terms concurrently embodied 

 in common language (69).* So that in the very language we use, 

 in the classifications embodied in it, and in the rough and ready 

 generalizations of ordinary life, we have to hand an abundance 

 of materials which suggest to the thoughtful mind new connexions 

 and relations, as hypotheses for verification. Observation will 

 often show the necessity of discarding or modifying customary 

 classifications, and of re-grouping things according to newly de 

 tected points of similarity or dissimilarity. But these processes 

 have their origin in the study and comparison of existing classes, 

 and in analysis of accepted generalizations. Thus, the relation 

 involved in an ordinary universal judgment &quot; All 5&quot; is P&quot; or 

 &quot; If 5 is M it is P &quot; may, perhaps, be a reciprocal ration : and 



tion, between an extremely high degree of probability and what is commonly called 

 certitude. And this is particularly true in the social and historical sciences. &quot; Speak 

 ing strictly and in accordance with correct logical usage,&quot; writes M. Ernest Naville 

 (La Logique de I Hypothese, p. 222), &quot; the highest probability cannot become certi 

 tude. And yet it is an indisputable fact that there are crowds of hypotheses upon 

 which we have no hesitation in acting as if they were absolutely certain. Practice 

 is here in advance of theory, and does not follow quite the same law.&quot; The kind 

 and amount of evidence required for verification, and for a certain assent, are not 

 identical in all the sciences. They vary with the subject-matter. 

 J Cf. JOSEPH, op. cil., pp. 413, 440. 



