146 HUME vi 



fingers, it is utterly impossible to conceive that 

 we have not two round objects under them; and, 

 though light is undoubtedly a mere sensation 

 arising in the brain, it is utterly impossible to 

 conceive that it is not outside the retina. In 

 the same way, he who touches anything with a 

 rod, not only is irresistibly led to believe that the 

 sensation of contact is at the end of the rod, but 

 is utterly incapable of conceiving that this sensa- 

 tion is really in his head. Yet that which is 

 inconceivable is manifestly true in all these cases. 

 The beliefs and the unbeliefs are alike necessary, 

 and alike erroneous.* 



It is commonly urged that the axiom of causa- 

 tion cannot be derived from experience, because 

 experience only proves that many things have 

 causes, whereas the axiom declares that all things 

 have causes. The syllogism, " many things which 

 come into existence have causes. A has come into 

 existence: therefore A had a cause," is obviously 

 fallacious, if A is not previously shown to be one 

 of the " many things/' And this objection is per- 

 fectly sound so far as it goes. The axiom of causa- 

 tion cannot possibly be deduced from any general 

 proposition which simply embodies experience. 

 But it does not follow that the belief, or expecta- 

 tion, expressed by the axiom, is not a product of 

 experience, generated antecedently to, and alto- 

 gether independently of, the logically unjustifiable 

 language in which we express it. 



