LAW OF CAUSATION. 265 



With regard to the modern philosophers (Leibnifz and the Cartesians) whom I had cited as 

 having maintained that the action of mind upon matter, so far from being the only conceiva- 

 ble origin of material phenomena, is itself inconceivable; the attempt to rebut this argument 

 by asserting that the mode, not the fact, of the action of mind on matter was lepresented as 

 inconceivable, is an abuse of the privilege of writing confidently about authors without read- 

 ing them ; for any knowledge whatever of Leibnitz would have taught those who thus speak 

 of him, that the inconceivability of the mode, and the impossibility of the thing, were in his 

 mind convertible expressions. What was his famous Princijjle of the Sufficient Reason, the 

 very corner-stone of his Philosophy, from which the Pre-established Harmony, tlie doctrine 

 of Monads, and all the opinions most characteristic of Leibnitz, were corollaries ? It was, 

 that nothing exists, the existence of which is not capable of being proved and explained a 

 priori ; the proof and explanation in the case of contingent facts being derived from the na- 

 ture of their causes ; which could not be the causes unless there was something in their nature 

 showing them to be capable of producing those particular effects. And this "something" 

 which accounts for the production of physical effects, he was able to find in many physical 

 causes, but could not find it in any finite minds, which therefore he unhesitatingly asserted to 

 be incapable of producing any physical effects whatever. " On ne saurait concevoir," he says, 

 " une action reciproque de la matiere et de I'intelligence Tune sur I'autre," and there is there- 

 fore (he contends) no choice but between the Occasional Causes of the Cartesians and his 

 own Pre-established Harmony, according to which there is no more connection between our 

 volitions and our muscular actions than there is between two clocks which are wound up 

 to strike at the same instant. But he felt no similar difficulty as to physical causes ; and 

 throughout his speculations, as in the passage I have already cited respecting gravitation, he 

 distinctly refuses to consider as part of the order of nature any fact which is not explicable 

 from the nature of its physical cause. 



With regard to the Cartesians (not Descartes ; I did not make that mistake, though the re- 

 viewer of Dr. Tulloch's Essay attributes it to me) I take a passage almost at random from 

 Malebranche, who is the best known of the Cartesians, and, though not the inventor of the sys- 

 tem of Occasional Causes, is its principal expositor. In Part II., chap, iii., of his Sixth Book, 

 having first said that matter can not have the power of moving itself, he proceeds to argue 

 that neither can mind have the power of moving it. " Quand on examine I'idee que Ton a de 

 tons les esprits finis, on ne voit point de liaison neccssaire entre leur volonte et le mouvement 

 de quelque corps que ce soit, on voit au contraire qu'il n'y en a point, et qu'il n'y en peut avoir " 

 (there is nothing in the idea of finite mind which can account for its causing the motion of a 

 body) ; "on doit aussi conclure, si on vent raisonner selon ses lumieres, qu'il n'y a aucun esprit 

 cree qui puisse remuer quelque corps que ce soit comme cause veritable on principale, de 

 meme que Ton a dit qu'aucun corps ne se pouvait remuer soi-meme :" thus the idea of Mind 

 is according to him as incompatible as the idea of Matter with the exercise of active force. 

 But when, he continues, we consider not a created but a Divine Mind, the case is altered; 

 for the idea of a Divine Mind includes omnipotence ; and the idea of omnipotence does con- 

 tain the idea of being able to move bodies. Thus it is the nature of omnipotence which ren- 

 ders the motion of bodies even by the Divine Mind credible or conceivable, while, so far as 

 depended on the mere nature of mind, it would have been inconceivable and incredible. If 

 Malebranche had not believed in an omnipotent Being, he would have held all action of mind 

 on body to be a demonstrated impossibility.* 



A doctrine more precisely the reverse of the Volitional theory of causation can not well be 

 imagined. The Volitional theory is, that we know by intuition or by direct experience the 

 action of our own mental volitions on matter ; that we may hence infer all other action upon 

 matter to be that of volition, and might thus know, without any other evidence, that matter 

 is under the government of a Divine Mind. Leibnitz and the Cartesians, on the contrary, 

 maintain that our volitions do not and can not act upon matter, and that it is only the ex- 

 istence of an all-governing Being, and that Being omnipotent, which can account for the se- 

 quence between our volitions and our bodily actions. When we consider that each of these two 

 theories, which, as theories of causation, stand at the opposite extremes of possible divergence 



for our uses. While I decline to express any opinion here on this vexata qucestio, I ought 

 not to mention Mr. Powell's volume without the acknowledgment due to the philosophic 

 spirit which pervades generally the three Essays composing it, forming in the case of one of 

 them (the "Unity of Worlds") an honorable contrast with the other dissertations, so far as 

 they have come under my notice, which have appeared on either side of that controversy. 



* In the words of Fontenelle, another celebrated Cartesian, "les philosophes aussi bien que 

 le peuple avaient cru que Tame et le corps agissaient reellement et physiquement I'un sur 

 I'autre. Descartes vint, qui prouva que leur nature ne permettait point cette sorte de com- 

 munication veritable, et qu'ils n'en pouvaient avoir qu'une apparente, dont Dieu etait le Medi- 

 ateur." — {(Euvres de Fontenelle, ed. 1767, torn, v., p, 634.) 



