348 



ON HUMAN UNDERSTANDING. 



upon the first point, by luckily finding out that he thinks, and, therefore, says 

 he gravely, I must be alive : Cogito, ergo sum. " I think, and therefore I am." 

 And he almost as soon satisfies himself upon the second, by feeling with his 

 hands about him, and finding out that he can run them against a something 

 or a somebody else, against a man or a post. He then returns home to him- 

 self once more, overjoyed with this demonstration of his fingers ; and com- 

 mences a second voyage of discovery by doubting whether he knows any 

 thing besides his own existence, and that of a something beyond him. And 

 he now ascertains, to his inexpressible satisfaction, that the soil of his own 

 mind is sown with indigenous ideas precisely like that of thought or con- 

 sciousness. These he digs up one after another, in order to examine them. 

 One of the first that turns up is that of a God : one of the next is an idea that 

 informs him that the outside of himself, or rather of his mind, is matter ; and 

 combining the whole he has thus far acquired with other information ob- 

 tained from the same sources, he finds that the people whom he has before 

 discovered by means of his hands and eyes call this matter a body, and that 

 the said people have bodies of the same kind, and also the same kind of 

 knowledge as himself, although not to the same extent or demonstration ; and 

 for this obvious reason, because they have not equally doubted and examined. 



It is difficult to be grave upon such a subject. What would be thought or 

 said of any individual in the present audience, who should rise up and 

 openly tell us that he had been long troubled with doubts whether he really 

 existed or not ; that his friends had told him he did, and he was inclined to 

 believe so ; but that as this belief might be a mere prejudice, he was at length 

 determined to try the fact by asking himself this plain question, — " Do I 

 think ]" Is there a person before me but would exclaim, almost instinctively, 

 " Ah ! poor creature, he had better ask himself another plain question, — 

 whether he is in his sober senses ]" 



If, however, we attempt to examine seriously the mode which M. Des 

 Cartes thus proposes of following up his own principles, it is impossible not 

 to be astonished at his departure from them at the first outset. Instead of 

 doubting of every thing and proving every thing, the very first position before 

 him he takes for granted : " I think, therefore I am." Of these two positions, 

 he makes the first the proof of the second, but what is the proof of the first ? 

 If it be necessary to prove that he is, the very groundwork of his system 

 renders it equally necessary to prove that he thinks. But this he does not 

 attempt to do : in direct contradiction to his fundamental principles he here 

 commits a. petitio principii, and takes it for granted. I do not find fault with 

 him for taking it for granted ; but then he might as well have saved himself 

 the trouble of manufacturing an imperfect syllogism, and have taken it for 

 granted also that he was alive or that he existed, for the last fact must have 

 been just as obvious to himself as the first, and somewhat more so to the 

 world at large. 



There is another logical error in this memorable enthymeme, or syllogism 

 without a head, which ought not to pass without notice ; I mean, that the 

 proof does not run parallel with the predicate, and, consequently, does not 

 answer its purpose. The subject predicated is, that the philosopher exists or 

 is alive, and to prove this he affirms gratuitously that he thinks. " I think, 

 and therefore I am." Now, in respect to the extent or parallelism of the 

 proof, he might just as well have said " I itch," or " I eat, and therefore I am." 

 I will not dispute that in all probability he thought more than he itched, or 

 partook of food : but let us take which proof we will, it could only be a proof 

 so long as he itched, or was eating ; and, consequently, whenever he ceased 

 from either of these conditions, upon his own argument, he would have no 

 proof whatever of being alive. Now, that he must often have ceased from 

 itching, or eating, there is no difficulty in admitting ; but then he may also at 

 times have ceased from thinking, not only in various morbid states of the 

 brain, but whenever he slept without dreaming. And hence, the utmost that 

 any such argument could decide in his favour, let us t£ike which kind of proof 

 we tvill, would be, that he could alternately prove himself to be alive and alter- 



