16 THE SCIENCE OF LOGIC. 



since the logician brings them to light from his analysis of thought, 

 not merely for the pleasure of contemplating them, but with a 

 view to using them : it is equally manifest that the science of 

 logic is rather a practical than a speculative science. Its im 

 mediate object being distinctly practical, it must be ranked as a 

 practical science. 



Finally, is logic not merely a practical science but even an 

 art ? In the narrower meaning, which would confine the scope 

 of this term to collections of rules for the execution of external 

 works, logic would not be an art. But if we extend the term to 

 those rules which direct even internal, mental activity, we may 

 legitimately call it an art the art of correct thinking, of accurate 

 reasoning. That is to say, the discovery and formulation of those 

 rules or canons which are no less the outcome of experience in 

 thinking than of an analytic study of the processes of thought 

 would be the practical science of logic ; and the application 

 of those rules, the actual reasoning according to those precepts 

 (whether unconsciously or consciously) would be the art of logic. 



Every art has some background of theoretical truths or principles behind 

 it ; every department of external experience has some counterpart or com 

 plement of internal, rational study. The system of practical rules and laws 

 arrived at by the study of our mental processes was called by the Scholastics 

 Logica Docens logic in the teaching; the application of those fruits of 

 study for the guidance of those processes, they called Logica Utens logic in 

 action. 



9. MENTAL PROCESSES INVOLVED IN KNOWING TRUTH: 

 SUBJECT-MATTER OF LOGIC : ITS DIVISIONS. We have said the 

 aim of logic is to lead us to a &quot; knowledge of the truth &quot;. When 

 is knowledge true and when is it false ? Knowledge can be neither 

 true nor false so long as the mind does not assert or deny any 

 thing, but confines itself to the simple contemplation of some object 

 of thought. When, for example, we merely think of the sun, or 

 the infallibility of the Pope, or a unicorn, our thoughts are neither 

 true nor false. Ideas as such are neither true nor false, nor is 

 the mental act of apprehension or conception by which we form 

 them, nor are the words of the dictionary which express them. 

 It is only when, by a more complex act, we compare and iden 

 tify, or distinguish between our ideas about objects, that our 

 knowledge assumes the character of truth or error. In other 

 words, it is only when we make a mental statement or pronounce 

 ment (enunciatio\ an affirmation or a denial of something about 



