180 ESSAY ON THE RATIONALE OF 



that " he who will not stir till he infallibly knows the business he 

 goes about will succeed, will have little else to do, but sit still and 

 perish."* But in such cases our judgments concern ourselves, and 

 our own duties and interests; while in moral judgments and penal 

 jurisprudence, a rule of action is applied to the conduct oi others, 

 where external and sometimes ambiguous indicia constitute the only 

 basis of judgment. In the ajiplication of a rule of action, the 

 moral certainty of the facts is its only just foundation and vindica- 

 tion, and upon any lower degree of assurance it would be arbitrary 

 and indefensible. 



But, though a process purely mathematical cannot be applied to 

 moral evidence, a proceeding somewhat analogous is always follow- 

 ed in the examination of a group of facts which are adduced as 

 reasons for inferring the existence of another fact. We mentally 

 collect on one side of the equation all the circumstances which 

 have an affirmative value, and on the other, all those which lead to 

 the opposite inference, or which diminish or destroy the weight or 

 relevancy of the facts which have been put into the opposite scale. 

 As in algebraic addition, we incorporate the opposite quantities, 

 positive and negative, and the balance of probabilities constitutes 

 the ground of human judgment and belief. 



The best writers on the subject of moral evidence, have been 

 unanimous in treating circumstantial as inferior in cogency to direct 

 evidence ; a conclusion which seems to follow necessarily from the 

 very nature of these different kinds of evidence. But assertions of 

 a different import are to be found in some late authorities. 



It has been said that '^ circumstances are inflexible proofs ; that 

 witnesses may be corrupted or mistaken, but things can be neither. "t 

 " Circumstances," says Paley " cannot lie." It is astonishing that 

 sophisms like these should have passed undetected. These pas- 

 sages assume the circumstances to be in every case established 

 beyond all possibility of mistake, and that the conclusions from 

 them are necessary and infallible; — and imply that circumstan- 

 tial evidence possesses some mysterious force peculiar to facts of 

 a certain class. Now, a circumstance is neither more nor less than 

 a minor fact ; and it may be admitted of all facts that they cannot 

 lie ; for a fact cannot at the same time exist and not exist, so that 

 the doctrine expresses a mere truism, that a fact is a fact. It may 

 also be admitted that circumstances are " inflexible proofs ;" but so 



• Essay on the Human Understandiny^ b. 4, c. 14, s. 1. 

 t Burnett, On the Criminal Law of Scotland. 



