316 



FALLACIES. 



are not able to leave out of the idea cannot be absent from 

 the reality.* This assumption pervades the philosophy not 

 only of Descartes, but of all the thinkers who received their 

 impulse mainly from him, in particular the two most remark- 

 able among them, Spinoza and Leibnitz, from whom the 

 modern German metaphysical philosophy is essentially an 

 emanation. I am indeed disposed to think that the fallacy 

 now under consideration has been the cause of two-thirds of 

 the bad philosophy, and especially 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 pro- 

 ceeded, and only could proceed, by laboriously finding in their 

 own minds what they themselves had formerly put there, and 

 evolving from 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 reasonableness, as it were out of their own 

 substance. 



The other form of the fallacy ; Things which we cannot 

 think of together cannot exist together, including as one of 

 its branches, that what we cannot think of as existing cannot 

 exist at all, may thus be briefly expressed : Whatever is 

 inconceivable must be false. 



Against this prevalent doctrine I have sufficiently argued 

 in a former Book,f and nothing is required in this place but 



* 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 properties of matter, and may 

 therefore be changeable, he concludes that it cannot be eternal, because " eternal 

 (passive) existence necessarily involves incapability of change." I believe it 

 would be difficult to point out any other connexion between the facts of eternity 

 and unchangeableness, than a strong association between the two ideas. Most 

 of the a priori arguments, both religious and anti-religious, on the origin of 

 things, are fallacies drawn from the same source. 



t Supra, book ii. chap. v. 6, and ch. vii. 1, 2, 3. See also Examination 

 of Sir William Hamilton's Philosophy, chap. vi. and elsewhere. 



