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tionally foolish state of mind ; for nothing can be more 

 foolish than to contradict oneself; and that is what 

 extreme sceptics are compelled, by pitiless logic, to do. 

 We have met with a notable example of this folly in the 

 case of Pyrrho* and his disciples the Pyrrhonists, who 

 refused even to affirm the truth of their own system. 

 If any one should venture to say " Nothing is cer- 

 tain," he would necessarily contradict himself, for he 

 would thereby, in the very same breath say, or at least 

 imply, that " something is certain," since he implies that 

 we may be certain nothing is certain. He says, or 

 implies, therefore, something which, if true, absolutely 

 contradicts what he has declared to be true. But a 

 man who affirms what the system he professes to adopt 

 forbids him to affirm, and who declares that he believes 

 what he also declares to be unbelievable, can hardly 

 complain if he is called foolish. If he denies that he 

 affirms anything, or even that he doubts about every- 

 thing, then, since he affirms nothing, we may disregard his 

 avowed folly, and the utter impotence he confesses to. 



Let us see a little further how self -refuting sceptical 

 modes of thought are. Suppose a man were to say : "I 

 cannot be sure of anything, because I cannot be certain 

 that my faculties are not always fallacious," or, "I 

 cannot be sure of anything, because, for all I know, I 

 may be the plaything of a demon who amuses himself 

 by constantly deceiving me " in both these cases such a 

 man would simply contradict himself. Jfor how can he 

 know that " constantly fallacious faculties," or, "a 

 demon deceiving in all things," will necessarily deprive 

 him of certainty ? Obviously he can only know this, 

 because he sees the necessary truth : "it is 



* See ante, p. 329. 



