t)EFINlTlON AND l^ROVINCE OF LOGIC.^ 



on these topics, it is almost univer- 

 sally allowed that the existence of 

 matter or of spirit, of space or of 

 time, is in its nature unsusceptible of 

 being proved ; and that if anything 

 is known of them, it must be by imme- 

 diate intuition. To the same science 

 belong the inquiiries into the nature 

 of Conception, Perception, Memory, 

 and Belief ; all of which are opera- 

 tions of the understanding in the 

 pursuit of truth ; but with which, as 

 phenomena of the mind, or with the 

 possibility which may or may not 

 exist of analysing any of them into 

 simpler phenomena, the 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 cl 2^riori 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 re- 

 stricted to that portion of our know- 

 ledge which consists of inferences from 

 truths previously 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 Evidence. 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 conscious- 

 ness, that is, without evidence in tlie 

 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 infer- 

 ences has been said to be the great 

 business of life. Every one has daily, 

 hourly, and momentary need of ascer- 

 taining facts which he has not directly 

 observed ; not from any general pur- 

 pose of adding to his stock of know- 

 ledge, but because the facts them- 

 selves are of importance to his in- 

 terests 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 accordingly. 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 of their several callings. It is 

 the only occupation in which the 

 mind never ceases to be engaged ; 

 and is the subject, not of logic, but 

 of knowledge in general. 



Logic, however, is not the same 

 thing with knowledge, though the 

 field of logic is coextensive with the 

 field of knowledge. Logic is the 

 common judge and arbiter of all par- 

 ticular investigations. It does not 

 undertake to find evidence, but to 

 determine whether it has been found. 

 Logic neither observes, nor invents, 

 nor discovers ; but judges. It is no 

 part of the business of logic to infox'm 

 the surgeon what appearances are 

 found to accompany a violent death. 

 This he must learn from his own 

 experience and observation, or from 

 that of others, his predecessors in his 

 peculiar pursuit. But logic sits in 

 judgment on the sufficiency of that 

 observation and experience to justify 

 his rules, and on the sufficiency of his 

 rules to justify his conduct. It does 

 not give him proofs, but teaches him 

 what makes them proofs, and how he 

 is to judge of them. It does not 

 teach that any particular fact proves 



