DEFINITION AND PROVINCE OF LOGIC. 



the accuracy of his deductions, but 

 for the extent of his command over 

 premises ; because the general propo- 

 sitions required for explaining a difl&- 

 culty or refuting a sophism, copiously 

 and promptly occur to him : because, 

 in short, his knowledge, besides being 

 ample, is well under his command for 

 argumentative use. Whether, there- 

 fore, we conform to the practice of 

 those who have made the subject 

 their particular study, or to that of 

 popular writers and common dis- 

 course, the province of logic will 

 include several operations of the intel- 

 lect not usually considered to fall 

 within the meaning of the terms 

 Reasoning and Argumentation. 



These various operations might be 

 brought within the compass of the 

 science, and the additional advantage 

 be obtained of a very simple defini- 

 tion, if, by an extension of the term, 

 sanctioned by high authorities, we 

 were to define logic as the science 

 which treats of the operations of the 

 human understanding in the pursuit 

 of truth. For to this ultimate end, 

 naming, classification, definition, and 

 all other operations over which logic 

 has ever claimed jurisdiction, are 

 essentially subsidiary. They may 

 all be regarded as contrivances for 

 enabling a person to know the truths 

 which are needful to him, and to 

 know them at the precise moment at 

 which they are needful. Other pur- 

 poses, indeed, are also served by these 

 operations ; for instance, that of im- 

 parting our knowledge to others. 

 But, viewed with regard to this pur- 

 pose, they have never been considered 

 as within the province of the logician. 

 The sole object of Logic is the guid- 

 ance of one's own thoughts : the 

 communication of those thoughts to 

 others falls under the consideration 

 of Rhetoric, in the large sense in 

 which that art was conceived by the 

 ancients ; or of the still more exten- 

 sive art of Education. Logic takes 

 cognizance of our intellectual opera- 

 tions, only as they conduce to our 



over that knowledge for our own 

 uses. If there were but one rational 

 being in the universe, that being 

 might be a perfect logician ; and the 

 science and art of logic would be the 

 same for that one person as for the 

 whole human race. 



§ 4. But, if the definition which 

 wo formerly examined included too 

 little, that which is now suggested 

 has the opposite fault of including 

 too much. 



Truths are known to us in two 

 ways : some are known directly, and 

 of themselves ; some through the 

 medium of other truths. The former 

 are the subject of Intuition, or Con- 

 sciousness ; * the latter, of Inference. 

 The truths known by intuition are 

 the original premises from which all 

 others are inferred. Our assent to 

 the conclusion being grounded on the 

 truth of the premises, we never could 

 arrive at any knowledge by reason- 

 ing, unless something could be known 

 antecedently to all reasoning. 



Examples of truths known to us by 

 immediate consciousness, are our own 

 bodily sensations and mental feelings. 

 I know directly, and of my own know- 

 ledge, that I was vexed yesterday, 

 or that I am hungry to-day. Ex- 

 amples of truths which we know only 

 by way of inference, are occurrences 

 which took place while we were 

 absent, the events recorded in history, 

 or the theorems of mathematics. The 

 two former we infer from the testi- 

 mony adduced, or from the traces of 

 those past occurrences which still 

 exist ; the latter, from the premises 

 laid down in books of geometry, under 

 the title of definitions and axioms. 

 Whatever we are capable of knowing 

 must belong to the one class or to 



* I use these terms indiscriminately, be- 

 cause, for the purpose in view, there is no 

 need for making any distinction between 

 tliem. But metapliysicians usually re- 

 strict the name Intuition to the direct 

 knowledge we are supposed to have of 

 things external to our minds, and Con- 

 sciousness to our knowledge of our own 

 mental phenomena. 



