[ ^'7 ] 



'• tions with like motives, inclinations and circumftances." In 

 the beginning of his Eflay he had laid, that " the fame motives 

 " always produce the fame ad ions ;" hut he afterwards explains 

 this affertion. " We muft not," he fays, " however exped that 

 " this uniformity of human adions fliall be carried to fuch a 

 " length as that all men in the fame circumftances will always ad 

 " precifely in the fame manner, without making any allowance 

 " for the diverfity of charaders, prejudices and opinions." 



The greateft efforts in metaphyfical inquiry appear then, by 

 the difficulties in which they are involved, to give confirmation 



to the opinion, that the nature of caufes and their manner of 



io:) 



operating are hid from us in impenetrable obfcurity. The at- 

 tempts made by Dodor Prieftley and Mr. Hume to eflablifli the 

 dodrine of Neceffity, have, I imagine, been fliewn to belong to 

 that clafs of inconclufive reafoning which logicians denominate 

 Petltio Principii^ and Dodor Gregory's attempt to overthrow it .to 

 belong to the clafs called Ignoratio Elanchi ; whilft on the queflion 

 of Materialifm Dodor Prieftley and Biftiop Berkeley refute each 

 other by contradidory arguments. Between this clafs of inquiries 

 and that in which we are capable of arriving at certainty lies the 

 clafs of mere Probability. In this middle clafs all the pradical, 

 and confequently all the immediately ufefuJ., knowledge of man- 

 kind is to be found. Mathematical fpeculations and the abftrad 

 rules of logical reafoning may boaft the high privilege of abfo- 

 lute certainty, but they are only ufeful as far as they are capable 

 of being applied to human adions ; and in this application the 

 mind of man muft be content with an affur^nce of lef^ ftrength. 

 Vol. V, E e The 



