DEFINITION AND PROVINCE OF LOGIC. 19 



man of powerful logic, not for the accuracy of his deductions, but for the 

 extent of his command over premises ; because the general propositions 

 required for explaining a difficulty or refuting a sophism, copiously and 

 promptly occur to him : because, in short, his knowledge, besides being 

 ample, is well nnder 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 discourse, the 

 province of logic will include several operations of the intellect not usually 

 considered to fall within the meaning of the terras Reasoning and Argu- 

 mentation. 



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 hu- 

 man understanding in the pursuit of truth. For to this ultimate end, nam- 

 ing, classification, definition, and all other operations over which logic has 

 ever claimed jurisdiction, are essentially subsidiary. They may all be re- 

 garded 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 purposes, indeed, are also served by these operations ; for 

 instance, that of imparting our knowledge to others. But, viewed with re- 

 gard to this purpose, they have never been considered as within the prov- 

 ince of the logician. The sole object of Logic is the guidance 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 con- 

 ceived by the ancients ; or of the still more extensive art of Education. 

 Logic takes cognizance of our intellectual operations only as they conduce 

 to our own knowledge, and to our command 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 we formerly examined included too lit- 

 tle, 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 Consciousness ;* 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 reasoning, 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 knowledge, that I was vexed yesterday, or that I am hungry to-day. 

 Examples of truths which we know only by way of inference, are occur- 

 rences which took place while we were absent, the events recorded in his- 

 tory, or the theorems of mathematics. The two former we infer from the 

 testimony adduced, or from the traces of those past occurrences which still 



* I use these tenns indiscriminately, because, for the pui-pose in view, there is no need for 

 making any distinction between them. But metaphysicians usually restrict the name Intui- 

 tion to the direct knowledge we are supposed to have of things external to our minds, and 

 Consciousness to our knowledge of our own mental phenomena. 



