vi CONCERNING NECESSARY TRUTHS 145 



the effect of a definite cause as the fact of its 

 falling; it is a proverb that "the wind bloweth 

 where it listeth "; and even thoughtful men usu- 

 ally receive with surprise the suggestion, that the 

 form of the crest of every wave that breaks, wind- 

 driven, on the sea-shore, and the direction of 

 every particle of foam that flies before the gale, 

 are the exact effects of definite causes; and, as 

 such, must be capable of being determined, de- 

 ductively, from the laws of motion and the prop- 

 erties of air and water. So again, there are 

 large numbers of highly intelligent persons who 

 rather pride themselves on their fixed belief that 

 our volitions have no cause; or that the will 

 causes itself, which is either the same thing, or a 

 contradiction in terms. 



Hume's argument in support of what appears 

 to be a true proposition, however, is of the circular 

 sort, for the major premiss, that all distinct ideas 

 are separable in thought, assumes the question at 

 issue. 



But the question whether the idea of causation 

 is necessary, or not, is really of very little impor- 

 tance. For, to say that an idea is necessary is 

 simply to affirm that we cannot conceive the con- 

 trary; and 'the fact that we cannot conceive the 

 contrary of any belief may be a presumption, but 

 is certainly no proof, of its truth. 



In the well-known experiment of touching a 

 single round object, such as a marble, with crossed 



