356 FALLACIES. 



found by previous inquirers in the facts. Neverthe- 

 less, the philosopher who more than all others has made 

 profession of rejecting authority, Descartes, constructed 

 his philosophical system on this very basis. His 

 favourite device for arriving at truth, even in regard to 

 outward things, was by looking into his own mind for 

 it. " Credidi me/' says his celebrated maxim, <c pro 

 regula generali sumere posse, omne id quod valde 

 dilucide et distincte concipiebam, verum esse:' ? what- 

 ever can be very clearly conceived, must certainly 

 exist; that is, as he afterwards explains it, if the idea 

 includes existence. And upon this ground he infers 

 that geometrical figures really exist, because they can 

 be distinctly conceived. Whenever existence is "in- 

 volved in an idea," a thing conformable to the idea 

 must really exist ; which is as much as to say, what- 

 ever 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 assump- 

 tion 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, Leibnitz and Spinosa, from whom 

 the modern German metaphysical philosophy is essen- 

 tially an emanation. The esteemed author of one of 

 the Bridgewater Treatises (which for its accumulation 

 of scientific facts, and even for some of its generaliza- 

 tions, is worthy of all praise) 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 there- 

 fore be changeable, he concludes that it cannot be 

 eternal, because " eternal (passive) existence neces- 

 sarily involves incapability of change." I believe it 

 would be difficult to point out any other connexion 



