SCIENCE 383 



arrive at conclusions which are certain, by means of what 

 is uncertain or false." But if he knows that truth if 

 he is certain of that universal principle he must know 

 that his faculties are not always fallacious, and that his 

 demon is impotent to deceive him in everything since 

 he can apprehend the certainty of the necessary truth 

 last stated. Universal doubt, then, is simply an absur- 

 dity. It is scepticism run mad, and no system can be 

 true, and no reasoning can be valid, of which the 

 inevitable result is scepticism of such a nature. 



Let us now see what would be the consequences of 

 uncertainty as to the validity of the reasoning process 

 and our mental faculties generally, of memory, of our 

 knowledge of our own existence, or of universal necessary 

 principles, or of the law of contradiction. 



As to reasoning,* and the trustworthiness of our 

 mental faculties generally, if any man is convinced that 

 thoughts are worthless tools, he can only have arrived at 

 that conclusion by using the very tools he professes to 

 consider worthless. What, then, ought his conclusions 

 to be worth even in his own eyes ? It is simply im- 

 possible by reason to get behind or beyond conscious 

 thought, and our thoughts are, and must be, our only 

 means of investigating fundamental problems. f If a 

 man professes to affirm that his faculties are untrust- 

 worthy, we of course are thereby debarred from bringing 

 home conviction to his mind. But it is no less im- 

 possible for him to defend his position. Once let him 

 attempt sincerely to do so, and he thereby plainly shows 

 that he really has confidence in reason and in language, 

 however much he may verbally deny that lie has it. It 



* For the consequences of scepticism as to this, see pp. 368 

 and 369. t See ante, p. 270. 



