626 FALLACIES. 



both these facts, and we find them equally inexplicable, but equally easy to 

 believe. To Newton, the one, because his imagination was familiar with it, 

 appeared natural and a matter of course, while the other, for the contrary 

 reason, seemed too absurd to be credited. 



It is strange that any one, after such a warning, should rely implicitly 

 on the evidence a priori of such propositions as these, that matter can not 

 think; that space, or extension, is infinite; that nothing can be made out 

 of nothing {ex nihilo nihil Jit). Whether these propositions are true or 

 not this is not the place to determine, nor even whether the questions are 

 soluble by the human faculties. But such doctrines are no more self-evi- 

 dent truths, than the ancient maxim that a thing can not act where it is 

 not, which probably is not now believed by any educated person in Eu- 

 rope.* Matter can not think; why? because we cmi not conceive thought 

 to be annexed to any arrangement of material particles. Space is infinite, 

 because having never known any part of it which had not other parts be- 

 yond it, we can not conceive an absolute termination. Ex nihilo nihil Jit, 

 because having never known any physical product without a pre-existing 

 physical material, we can not, or think we can not, imagine a creation out 

 of nothing. But these things may in themselves be as conceivable as 

 gravitation without an intervening medium, which Newton thought too 

 great an absurdity for any person of a competent faculty of philosophical 

 thinking to admit: and even supposing them not conceivable, this, for 

 aught we know, may be merely one of the limitations of our very limited 

 minds, and not in nature at all. 



No writer has more directly identified himself with the fallacy now un- 

 der consideration, or has embodied it in more distinct terms, than Leibnitz. 

 In his view, unless a thing was not merely conceivable, but even explaina- 

 ble, it could not exist in nature. All natural phenomena, according to him, 

 must be susceptible of being accounted for a priori. The only facts of 

 which no explanation could be given but the will of God, were miracles 

 properly so called. "Je reconnais," says he,f "qu'il n'est pas permis de 

 nier ce qu'on n'entend pas ; raais j'ajoute qu'on a droit de nier (au moins 

 dans I'ordre naturel) ce que absolument n'est point intelligible ni explicable. 

 Je soutiens aussi .... qu'enfin la conception des creatures n'est pas la me- 

 sure du poavoir de Dieu, mais que leur conceptiviie, ou force de concevoir, 

 est la mesure du pouvoir de la nature, tout ce qui est conforme a I'ordre 

 naturel pouvant etre congu ou entendu par quelque creature." 



Not content with assuming that nothing can be true which we\are unable 

 to conceive, scientific inquirers have frequently given a still further exten- 

 sion to the doctrine, and held that, even of things not altogether inconceiv- 

 able, that which we can conceive with the greatest ease is likeliest to be 

 true. It was long an admitted axiom, and is not yet entirely discredited, 

 that "nature always acts by the simplest means," «.e., by those which are 

 most easily conceivable.| A large proportion of all the errors ever commit- 

 ted in the investigation of the laws of nature, have arisen from the assump- 

 tion that the most familiar explanation or hypothesis must be the truest. 



* This statement I must now correct, as too unqualified. The maxim in question was 

 maintained with full conviction by no less an authority than Sir William Hamilton. See my 

 Examination, chap. xxiv. 



t Nouveaux Essais sur VEntendement Humain — Avant-propos. (CEuvres, Paiis ed., 1842, 

 vol. i., p. 19.) 



t This doctrine also was accepted as true, and conclusions wore giounded on it, by Sir 

 William Hamilton. See Examination, chap. xxiv. 



