160 REASONING. 



more, m order to overthrow the whole theory of Mr. Whewell on the 

 nature of the evidence of axioms. For what is that theory ? That the 

 truth of axioms cannot have been learnt from experience, because their 

 falsity is inconceivable. But Mr. Whewell himself says, that we are 

 continually led by the natural progress of thought, to regard as incon- 

 ceivable what our forefathers not only conceived but believed, nay, 

 even (he might have added) were unable to conceive the contrarv of. 

 Mr. Whewell cannot intend to justify this mode of thought ; he cannot 

 mean to say, that we can be right in regarding as inconceivable what 

 others have conceived, and as self-evident what to others did not appear 

 e\"ident at all. After so complete an admission that inconceivablenesa 

 is an accidental thing, not inherent in the phenomenon itself, but de- 

 pendent on the mental history of the person who tries to conceive it, 

 how can he ever call upon us to reject a proposition as impossible on 

 no other gi'ound than its inconceivableness ? Yet he not only does so, 

 but has unintentionally afforded some of the most remarkable exam- 

 ples which can be cited of the very illusion which he has himself so 

 clearly pointed out. W^e select as specimens, his remarks on the evi- 

 dence of the three laws of motion, and of the atomic theory. 



With respect to the laws of motion, Mr. Whewell says : " No one 

 can doubt that, in historical fact, these laws were collected from expe- 

 rience. That such is the case is no matter of conjecture. We know 

 the time, the persons, the circumstances, belonging to each step of each 

 discovery."* After such a testimony, to adduce evidence of the fact 

 would be supei-fluous. And not only were these laws by no means 

 intuitively evident, but some of them were originally paradoxes. The 

 first law was especially so. That a body, once in motion, would con- 

 tinue for ever to move in the same direction with undiminished velo- 

 city unless acted upon by some new force, was a proposition which 

 mankind found for a long time the gi'eatest difficulty in crediting. It 

 stood opposed to apparent experience of the most familiar kind, which 

 taught that it was the nature of motion to abate gradually, and at last 

 terminate of itself Yet when once the contrary doctrine was firmly 

 established, mathematicians, as Mr. Whewell observes, speedily began 

 to believe that laws, thus conti-adictory to first appearances, and which, 

 even after full proof had been obtained, it had required generations to 

 render familiar to the minds of the scientific world, were under " a 

 demonsti'able necessity, compelling them to be such as they are and 

 no other ;" and ]Mr. Wliewell, though he has " not ventured absolutely 

 to pronounce" that all these laws " can be rigorously traced to an ab- 

 solute necessity in the nature of things, "t does actually think in that 

 manner of the law just mentioned ; of which he says : " Though the 

 discovery of the first law of motion was made, historically speaking, by 

 means of experiment, we have now attained a point of view in which 

 we see that it might have been certainly kno\\Ti to be true, independ- 

 ently of experience."! Can there be a more striking exemplification 

 than is here afforded, of the effect of association which we have de- 

 scribed \ Philosophers, for generations, have the most exta-aordinary 

 difficulty in putting certain ideas together ; they at last succeed in doing 

 so; and after a sufficient repetition of the process, they first fancy a 

 natural bond between the ideas, then experience a growing difficulty 



* Philosophy of the Liduxtiue Sciaices, i., 238. t Ibid., 237. t Ibid, 213. 



