FALLACIES OP SIMPLE INSPECTION. 325 



any other law of the universe, is experience ; it is simply that 

 no other suppositions explain or are consistent with the facts 

 of universal nature. 



Geometers have, in all ages, been open to the imputation 

 of endeavouring to prove the most general facts of the outward 

 world hy sophistical reasoning, in order to avoid appeals to 

 the senses. Archimedes, says Professor Playfair,* established 

 some of the elementary propositions of statics by a process in 

 which he " borrows no principle from experiment, but estab- 

 lishes his conclusion entirely by reasoning a priori. He 

 assumes, indeed, that equal bodies, at the ends of the equal 

 arms of a lever, will balance one another ; and also that a 

 cylinder or parallelepiped of homogeneous matter, will be 

 balanced about its centre of magnitude. These, however, are 

 not inferences from experience ; they are, properly speaking, 

 conclusions deduced from the principle of the Sufficient 

 Keason." And to this day there are few geometers who would 

 not think it far more scientific to establish these or any other 

 premises in this way, than to rest their evidence on that 

 familiar experience which in the case in question might have 

 been so safely appealed to. 



6. Another natural prejudice, of most extensive pre- 

 valence, and which had a great share in producing the errors 

 fallen into by the ancients in their physical inquiries, was 

 this : That the differences in nature must correspond to our 

 received distinctions ; that effects which we are accustomed, 

 in popular language, to call by different names, and arrange 

 in different classes, must be of different natures, and have 

 different causes. This prejudice, so evidently of the same 

 origin with those already treated of, marks more especially the 

 earliest stage of science, when it has not yet broken loose 

 from the trammels of every-day phraseology. The extraor- 

 dinary prevalence of the fallacy among the Greek philosophers 

 may be accounted for by their generally knowing no other 

 language than their own ; from which it was a consequence 



* Dissertation, ut supra, p. 27. 



