8 INTRODUCTION. 



logician as such has no concern. To this science must also be 

 referred the following, and all analogous questions : To what 

 extent our intellectual faculties and our emotions are innate 

 to what extent the result of association : Whether God, and 

 duty, are realities, the existence of which is manifest to us 

 efc priori by the constitution of our rational faculty ; or whether 

 our ideas of them are acquired notions, the origin of which we 

 are able to trace and explain ; and the reality of the objects 

 themselves a question not of consciousness or intuition, but of 

 evidence and reasoning. 



The province of logic must be restricted to that portion of 

 our knowledge which consists of inferences from truths pre- 

 viously known ; whether those antecedent data be general pro- 

 positions, or particular observations and perceptions. Logic 

 is not the science of Belief, but the science of Proof, or Evi- 

 dence. In so far as belief professes to be founded on proof, 

 the office of logic is to supply a test for ascertaining whether 

 or not the belief is well grounded. With the claims which any 

 proposition has to belief on the evidence of consciousness, that 

 is, without evidence in the proper sense of the word, logic has 

 nothing to do. 



5. By far the greatest portion of our knowledge, 

 whether of general truths or of particular facts, being avowedly 

 matter of inference, nearly the whole, not only of science, but 

 of human conduct, is amenable to the authority of logic. To 

 draw inferences has been said to be the great business of life. 

 Every one has daily, hourly, and momentary need of ascertain- 

 ing facts which he has not directly observed ; not from any 

 general purpose of adding to his stock of knowledge, but 

 because the facts themselves are of importance to his interests 

 or to his occupations. The business of the magistrate, of the 

 military commander, of the navigator, of the physician, of the 

 agriculturist, is merely to judge of evidence, and to act accord- 

 ingly. They all have to ascertain certain facts, in order that 

 they may afterwards apply certain rules, either devised by 

 themselves, or prescribed for their guidance by others ; and as 

 they do this well or ill, so they discharge well or ill the duties 



