l82 



REASONING. 



unanimously declare the same thing. 

 It is true, even this experience may 

 be insufficient, and so it might be 

 even if I could recall to mind every 

 instance of it : but its insufficiency, 

 instead of being brought to light, is 

 disguised, if, instead of sifting the 

 experience itself, I appeal to a test 

 which bears no relation to the suffi- 

 ciency of the experience, but, at the 

 most, only to its familiarity. These 

 remarks do not lose their force even 

 if we believe, with Mr. Spencer, that 

 mental tendencies originally derived 

 from experience impress themselves 

 permanently on the cerebral structure 

 and are transmitted by inheritance, 

 BO that modes of thinking which are 

 acquired by the race become innate 

 and a priori in the individual, thus 

 representing, in Mr. Spencer's opinion, 

 the experience of his progenitors, in 

 addition to his own. All that would 

 follow from this is, that a conviction 

 might be really innate, i.e. prior to 

 individual experience, and yet not be 

 true, since the inherited tendency to 

 accept it may have been originally 

 the result of other causes than its 

 truth. 



Mr. Spencer would have a much 

 stronger case if he could really show 

 that the evidence of Reasoning rests 

 on the Postulate, or, in other words, 

 that we believe that a conclusion 

 follows from premises only because 

 we cannot conceive it not to follow. 

 But this statement seems to me to be 

 of the same kind as one I have pre- 

 viously commented on, viz. that I 

 believe I see light, because I cannot, 

 while the sensation remains, conceive 

 that I am looking into darkness. 

 Both these statements seem to me 

 incompatible with the meaning (as 

 very rightly limited by Mr. Spencer) 

 of the verb to conceive. To say that 

 when I apprehend that A is B and 

 that B is C, I cannot conceive that A 

 is not C, is to my mind merely to say 

 that I am compelled to believe that A 

 is C. If to conceive be taken in its 

 proper meaning, viz. to form a mental 

 representation, I may be able to con- 



ceive A as not being C After 

 assenting, with full understanding, 

 to the Copernican proof that it is the 

 earth and not the sun that moves, I 

 not only can conceive, or represent to 

 myself, sunset as a motion of the sun, 

 but almost every one finds this con- 

 ception of sunset easier to form than 

 that which they nevertheless know to 

 be the true one. 



§ 5. Sir William Hamilton holds as 

 I do, that inconceivability is no crite- 

 rion of impossibility. "There is no 

 ground for inferring a certain fact to 

 be impossible, merely from our inabil- 

 ity toconceive its possibility." "Things 

 there are which may, nay must, be 

 true, of which the understanding is 

 wholly unable to construe to itself the 

 possibility." * Sir William Hamilton 

 is, however, a firm believer in the a 

 priori character of many axioms, and 

 of the sciences deduced from them ; 

 and is so far from considering those 

 axioms to rest on the evidence of ex- 

 perience, that he declares certain of 

 them to be true even of Noumena — of 

 the Unconditioned — of which it is one 

 of the principal aims of his philosophy 

 to prove that the nature of our facul- 

 ties debars us from having any know- 

 ledge. The axioms to which he attri- 

 butes this exceptional emancipation 

 from the limits which confine aU our 

 other possibilities of knowledge ; the 

 chinks through which, as he represents, 

 one ray of light finds its way to us 

 from behind the curtain which veils 

 from us the mysterious world of Things 

 in themselves, — are the two principles 

 which he terms, after the schoolmen, 

 the Principle of Contradiction and 

 the Principle of Excluded Middle: 

 the first, that two contradictory pro- 

 positions cannot both be true ; the 

 second, that they cannot both be false. 

 Armed with these logical weapons, 

 we may boldly face Things in them- 

 selves, and tender to them the double 

 alternative, sure that they must abso- 

 lutely elect one or the other side, 



* Discussions, (be, 2d ed. p. 634. 



