SECTION 12 HYPOTHESES. 91 



removed in milling counteracts the effects of an excessive starch 

 diet. A plausible assertion is not identical with a hypothesis, 

 because in ordinary life such an assertion is not regarded as 

 demanding proof: it is either conceived as being probable 

 without any reference to proof, or, what is more frequent, the 

 plausibility is at once mentally converted into a certainty. For 

 primitive thinkers proof is something subjective; that is, if a 

 statement forcibly appeals to the feelings, it is forthwith judged 

 to be true. The strongholds of ignorance and error are paved 

 with plausible assertions and sprinkled with stray facts. Hence 

 it would be advisable that terms, such as supposition, conjecture, 

 surmise, suggestion, guess, assumption, should not be considered 

 as co-extensive in methodological signification with the scienti- 

 fically well-established tepm Hypothesis *Which implies that we 

 are searching for proof of an assertion grounded primarily on 

 scientific observation or deduction. To this needs to be added 

 that hypotheses are near neighbours to appropriate fictions or 

 working hypotheses. 1 



How is a hypothesis formed? Mill speaks of the "manner 

 in which a conception is selected suitable to express the facts", 

 and affirms "that the process is tentative; that it consists of 

 a succession of guesses ; many being rejected, until one at last 

 occurs fit to be chosen". Significantly enough, "the guesses 

 which serve to give mental unity and wholeness to a chaos of 

 scattered particulars are accidents [?] which rarely occur to any 

 minds but those abounding in knowledge and disciplined in 

 intellectual combinations". (Logic, bk. 3, ch. 2, 4.) "An hypo- 

 thesis", Mill declares, "being a mere supposition, there are no 

 other limits to hypotheses than those of the human imagination." 

 (Ibid., bk. 3, ch. 14, 4.) And further on: "The process of 

 tracing regularity in any complicated, and at first sight confused, 

 set of appearances, is necessarily tentative : we begin by making 

 any supposition, even a false one, to see what consequences 

 will follow from it; and by observing how these differ from 

 the real phenomena, we learn what corrections to make in our 

 assumption." (Ibid., bk. 3, ch. 14, 5.) Finally, in what seems 

 his most explicit passage on the subject, Mill states: "Let any 

 one watch the manner in which he himself unravels a compli- 

 cated mass of evidence ; let him observe how, for instance, he 



1 Working hypotheses are frequently "leading" hypotheses, aud in their 

 case proof or disproof may occupy centuries, the largest working hypotheses 

 having the longest life as a rule owing to the difficulty of proving much 

 where relatively little is known. Such hypotheses are often admitted to be 

 seriously defective, but they are retained until more satisfactory ones are 

 forthcoming, e.g., Newton's corpuscular theory of light was displaced by 

 Young's undulatory theory of light, because the latter agreed better with 

 the known facts. (A combination of the two theories is now being tested.) 

 In ordinary hypotheses, of course, complete, or very nearly complete, proof. 

 is attainable, e.g., whether the shadow I observe is caused by a cloud or 

 a certain near object. 



