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All enquiries with regard to teftimony may be reduced to 

 two heads : In proportion as we are fatisfied that a witnefs has 

 not been influenced by any defire of deceiving* and has not 

 himfelf been deceived, we give credit to his teftimony. The 

 examination then by which we eflimatc the credit due to 

 teftimony confifts of two parts, and if it fhall appear that each is 

 a confideration of the connexion of caufe and effeB^ it will be al- 

 lowed that all propofitions whofe credit refts upon teftimony are 

 rightly claffed. 



When we wifh to determine whether a witnefs has been 

 influenced by a defire of deceiving, we confider what motives 

 could have induced him to wifti to deceive us, or whether the 

 means which he employed could promife him fuccefs in a fcheme 

 of deception. The former confideration is evidently an enquiry 

 into the operation of motives, that is, of moral caufes on his 

 mind ; and the latter will, I think, appear after a little confi- 

 fideration to be an enquiry of the fame kind, though fomewhat 

 more complicated. An enquiry into his judgment of the pro- 

 bability of his fuccefs, is an enquiry into the operation of a view 

 of the circumftances in which he was placed, confidered as a 

 motive which fhould determine him in the formation of his 

 plan of aclion. It is therefore an enquiry of the fame kind. 

 It is however a more complicated enquiry, becaufe it is made 

 for the purpofe of enabling us to form a judgment of his judg- 

 ment of his fituation. He deliberates about the operation of ' 

 motives on the minds of others in difpofing them to concur with 

 his fcheme or to oppofe it \ but we, from our view ' of his 

 fituation, deliberate about the expeftation which he muft have 



entertained.! 



