174 



REASONING. 



perience ; and if . . . these absolute 

 uniformities in our experience disable 

 us from conceiving the negations of 

 them ; then answering to each ab- 

 solute uniformity in nature which we 

 can cognise, there must exist in us a 

 belief of which the negation is incon- 

 ceivable, and which is absolutely true. 

 In this wide range of cases subjective 

 inconceivableness must correspond to 

 objective impossibility. Tiirther ex- 

 perience will produce correspondence 

 where it may not yet exist ; and we 

 may expect the correspondence to be- 

 come ultimately complete. In nearly 

 all cases this test of inconceivableness 

 must be valid now " — (I wish I could 

 think we were so nearly arrived at 

 omniscience) — " and where it is not, it 

 still expresses the net result of our 

 experience up to the present time ; 

 which is the most that any test can 

 do." 



To this I answer, first, that it is 

 by no means true that the inconceiv- 

 ability, by us, of the negative of a 

 proposition proves all, or even any, 

 •* pre-existing experience " to be in 

 favour of the affirmative. There may 

 have been no such pre-existing experi- 

 ences, but only a mistaken supposi- 

 tion of experience. How did the in- 

 conceivability of antipodes prove that 

 experience had given any testimony 

 against their possibility? How did 

 the incapacity men felt of conceiving 

 sunset otherwise than as a motion of 

 the sun, represent any " net result " 

 of experience in support of its being 

 the sun and not the earth that moves ? 

 It is not experience that is repre- 

 sented, it is only a superficial resem- 

 blance of experience. The only thing 

 proved with regard to real experience 

 is the negative fact that men have 

 not had it of the kind which would 

 have made the inconceivable proposi- 

 tion conceivable. 



Next : Even if it were true that in- 

 conceivableness represents the net 

 result of all past experience, why should 

 we stop at the representative when we 

 can get at the thing represented ? If 

 our incapacity to conceive the negation 



of a given supposition is proof of ita 

 truth, because proving that our ex- 

 perience has hitherto been uniform in 

 its favour, the real evidence for the 

 supposition is not the inconceivable- 

 ness, but the uniformity of experience. 

 Now this, which is the substantial 

 and only proof, is directly accessible. 

 We are not obliged to presume it from 

 an incidental consequence. If all past 

 experience is in favour of a belief, let 

 this be stated, and the belief openly 

 rested on that ground : after which 

 the question arises, what that fact 

 may be worth as evidence of its truth ? 

 For uniformity of experience is evi- 

 dence in very different degrees : in 

 some cases it is strong evidence, in 

 others weak, in others it scarcely 

 amounts to evidence at all. That all 

 metals sink in water, was an uniform 

 experience, from the origin of the 

 human race to the discovery of potas- 

 sium in the present century by Sir 

 Humphry Davy. That all swans are 

 white, was an uniform experience down 

 to the discovery of Australia. In the 

 few cases in which uniformity of ex- 

 perience does amount to the strongest 

 possible proof, as with such proposi- 

 tions as these, Two straight lines can- 

 not enclose a space, Every event has 

 a cause, it is not because their nega- 

 tions are inconceivable, which is not 

 always the fact, but because the ex- 

 perience, which has been thus uniform, 

 pervades all nature. It will be shown 

 in the following Book that none of 

 the conclusions either of induction or 

 of deduction can be considered certain, 

 except as far as their truth is shown 

 to be inseparably bound up with truths 

 of this class. 



I maintain then, first, that unifor- 

 mity of past experience is very far 

 from being universally a criterion of 

 truth. But, secondly, inconceivable- 

 ness is still farther from being a test 

 even of that test. Uniformity of 

 contrary experience is only one of 

 many causes of inconceivability. Tra- 

 dition handed down from a period of 

 more limited knowledge is one of the 

 commonest, The mere familiarity of 



