492 



I'ALLACIES. 



Things which we cannot think of ex- 

 cept together, must exist together. 

 This is assumed in the generally re- 

 ceived and accredited mode of reason- 

 ing which concludes that A must ac- 

 company B in point of fact, because 

 " it is involved in the idea," Such 

 thinkers do not reflect that the idea, 

 being a result of abstraction, ought to 

 conform to the facts, and cannot make 

 the facts conform to it. The argu- 

 ment is at most admissible as an 

 appeal to authority ; a surmise, that 

 what is now part of the idea must, 

 before it became so, have been found 

 by previous inquirers in the facts. 

 Nevertheless, the philosopher who 

 more than all others made professions 

 of rejecting authority, Descartes, con- 

 structed his system on this very iDasis. 

 His favourite device for arriving at 

 the truth, even in regard to outward 

 things, was by looking into his own 

 mind for it. " Credidi me," says his 

 celebrated maxim, " pro regul^ gene- 

 rali sum ere posse, omne id quod val- 

 de dilucid^ et distincte concipiebam, 

 verum esse ; " whatever can be very 

 clearly conceived must certainly exist; 

 that is, as he afterwards explains it, if 

 the idea includes existence. And on 

 this ground he infers that geometrical 

 figures really exist, because they can 

 be distinctly conceived. Whenever 

 existence is " involved in an idea," a 

 thing conformable to the idea must 

 really exist ; which is as much as to 

 say, whatever the idea contains must 

 have its equivalent in the thing ; and 

 •what we are not able to leave out of 

 the idea cannot be absent from the 

 reality.* This assumption pervades 



* The author of one of the Bridgewater 

 Treatises has fallen, as it seems to me, into 

 a similar fallacy when, after arguing in 

 rather a curious way to prove that matter 

 may exist without any of the known pro- 

 perties of matter, and may therefore be 

 changeable, he concludes that it cannot be 

 eternal, because " eternal (passive) exist- 

 ence necessarily involves incapability of 

 change." I believe it would be diflBcult to 

 point out any other connection between 

 the facts of eternity and unchangeableness 

 than a strong association between the two 

 ideas. Most of the d priori arguments, 



the philosophy not only of Descartes, 

 but of all the thinkers who received 

 their impulse mainly from him ; in 

 particular the two most remarkable 

 among them, Spinoza and Leibnitz, 

 from whom the modern German meta- 

 physical philosophy is essentially an 

 emanation, I am indeed disposed to jH 

 think that the fallacy now under con- S 

 sideration has been the cause of two- 

 thirds of the bad philosophy, and espe- 

 cially of the bad metaphysics, which 

 the human mind has never ceased to 

 produce. Our general ideas contain 

 nothing but what has been put into 

 them, either by our passive experience, 

 or by our active habits of thought ; 

 and the metaphysicians in all ages, 

 who have attempted to construct the 

 laws of the universe by reasoning from 

 our supposed necessities of thought, 

 have always proceeded, and only could 

 proceed, by laboriously finding in their 

 own minds what they themselves had ^M 

 formerly put there, and evolving from ^M 

 their ideas of things what they had 

 first involved in those ideas. In this 

 way all deeply-rooted opinions and 

 feelings are enabled to create apparent 

 demonstrations of their truth and rea- 

 sonableness, as it were out of their own 

 substance. 



The other form of the fallacy — 

 Things which we cannot think of to- 

 gether cannot exist together, — includ- 

 ing, as one of its branches, that what 

 we cannot think of as existing cannot 

 exist at all, — may thus be briefly ex- 

 pressed : Whatever is inconceivable 

 must be false. 



Against this prevalent doctrine I 

 have sufficiently argued in a former 

 Book,* and nothing is required in this 

 place but examples. It was long held 

 that Antipodes were impossible be- 

 cause of the difficulty which was found 

 in conceiving persons with their heads 

 in the same direction as our feet. And 



both religions and anti-religious, on the 

 origin of things, are fallacies drawn from 

 the same source. 



* Supra, book ii. chap. v. § 6, and ch. vii. 

 § T, 2, 3, 4, See also Examination of Sir 

 Willinm Hamilton's Philotopfnj, chap. vi. 

 and elsewhere. 



I 



