THE HUMAN SCIENCES 43 



The discovery of this foundation for human knowledge 

 is regarded as being especially the task of the philosopher ; 

 and the philosopher has undertaken it, sometimes in a 

 highly picturesque way, as in the case of Descartes. 

 Having discovered the insecurity of ordinary opinion and 

 found that even the sciences are based on hypotheses, and 

 being unwilling "to lean upon principles which he has 

 taken on trust," he sets himself to pull down the ' ' edifice " 

 of experience, never staying his hands till he finds some 

 truth that is valid in its own right. Descartes thought 

 that his C0P7/0, er?o sum .was such a truth. Doubt itself 



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had to assume it ; and that being the case, his Cogito, 

 ergo sum offered a foundation for knowledge which was 

 ultimate and could not be shaken. But his successors, 

 on analysing it, discovered that it was full of implications. 

 It consisted of only three terms, but every one of them 

 was complex, and stood in need of vindication. Hence 

 they must dig deeper in order to find a safe " foundation." 

 They must find some simple truth, some sensation, im- 

 pression, intuition, axiom, dictum of common-sense, a 

 priori principle of knowledge which is valid in its own 

 exclusive right. But the result has invariably been the 

 same. No idea could be found which did not imply 

 another idea, and which did not lose its meaning and 

 become useless if it was divested of these implications. 

 The search was intrinsically futile. It was a search after 

 what does not exist. 



Then followed, as usual, the distrust of human reason 

 itself. Man's thought was called relative : its doom is to 

 go back from condition to condition in an endless regress, 

 and to hang its chain of knowledge upon nothingness. 

 Or should not philosophy take to working miracles, and 



