CHAMBERS'S INFORMATION FOR THE PEOPLE. 



and Logic also makes a division of names to 

 suit its purposes. Two distinctions among names 

 are of value to the logician : the distinction 

 between General and Singular names, and the 

 distinction between Positive and Negative 

 names. 



'A Singular or Individual Name is a name 

 applicable to one thing. A General Name is 

 applicable to a number of things, in virtue of 

 their being similar, or having something in com- 

 mon.' Bain. Individual or Proper names serve 

 merely the purpose of marking out some one thing 

 from among the multitude of things at large, 

 exactly as could be done by pointing to it with 

 the finger, or in any way indicating it to another 

 person. Such names as England, Nile, Mont 

 Blanc, Niagara, Napoleon, give no information 

 about the things that they denote : they imply 

 no properties or attributes, and may be names of 

 dogs, cats, or prize oxen. Now, Logic having to 

 do with assertions about the properties of things, 

 has little concern with these Singular names, 

 except when it has to keep you consistent in your 

 affirmations regarding whatever they are applied 

 to. The names of interest in Logic are General 

 names country, river, mountain, waterfall, man 

 each of which is applied to many different things, 

 in different ages and regions, to indicate what 

 they have in common. General names are said to 

 have a meaning, or connotation : they imply the 

 possession of certain attributes common to all the 

 individuals that they are applied to. 



Next for the distinction between Positive and 

 Negative names. This is more subtle, and cannot 

 here be fully explained. When you make an 

 assertion about a subject, you must always by 

 implication deny something : when you say that a 

 bar of iron is hot, you virtually deny that it is cold. 

 Such names as hot cold, wet dry, fresh weary, 

 are called positive and negative names : the one 

 is negative to the other's positive, and positive to 

 the other's negative. If we were to enter fully 

 into this distinction, we should have to shew that 

 nothing is known except by reference to an oppo- 

 site a principle called the Relativity of Know- 

 ledge ; but it is enough for our present purposes 

 to say that in logical operations it is often 

 useful to regard all the things denoted by a 

 general name man, good as standing by them- 

 selves against all the things that are <5>/-man, not- 

 good, all the things that the general name can not 

 be applied to. 



" Classes, Notions, or Concepts. 



Both of the above divisions of names proceed 

 upon the arrangement of things in Classes. 

 Things are arranged in classes, as already indi- 

 cated, on the ground of possessing a common 

 property or properties, a point or points of like- 

 ness : round things form a class on the ground 

 of their roundness ; churches, on the ground of 

 their being public buildings used for religious 

 worship. When the points of agreement in a 

 class are thought of in the abstract, they are 

 said to form a Notion or Concept : being a build- 

 ing, being public, and being used for religious 

 worship, form .the concept or notion of a church. 

 The general name is said to denote the class, and 

 to connote the notion or points of community 

 among the individuals composing the class. 



354 



The greater the number of points of community, 

 the smaller the class, and inversely. ' Men' is a 

 smaller class than ' animals,' and the individuals 

 of the class have more in common. Classes are 

 divided into Higher and Lower according to their 

 extent. A higher class is called a Genus with 

 reference to its lower classes, which are said to 

 be Species under it. Animal is a genus, under 

 which man, bird, fish are species. The points 

 wherein one species differs from all other species 

 under the same genus are called its Differentia. 



Assertions, or Propositions. 



When an assertion is made concerning a whole 

 class, it is said to be a Total or Universal Pro- 

 position ; when it is made concerning a portion 

 of a class, it is said to be a Partial or Particular 

 Proposition. This is said to be a distinction in the 

 Quantity of Propositions. The logical forms are : 

 All A is B, and Some A is B. In common speech, 

 the quantity is often left indefinite, and one of the 

 reasoner's first considerations should be directed 

 to the real quantity intended. Do ' Honesty 

 is the best policy,' and ' Haste makes waste,' 

 belong to the form All A is B, or to the form 

 Some A is B ? Are the assertions universal or 

 partial ? Do they apply to all honest actions, to 

 all hasty actions, or to some f 



Propositions are also divided into Affirmative 

 and Negative, which is said to be a distinction 

 according to Quality. The above forms are Affirm- 

 ative. The Negative forms are : No A is B 

 (Universal), and Some A is not B (Particular}. 

 The Negative Universal is the complete and un- 

 compromising contradiction of the Affirmative 

 Universal ; the Particular Negative is a mild limi- 

 tation. All Propositions are either Universal 

 Affirmatives, or Particular Affirmatives, or Uni- 

 versal Negatives, or Particular Negatives. 



When you affirm anything, you always by 

 implication deny something else, and it is import- 

 ant to know what the various forms commit you 

 to ; in other words, what terms are convertible. 

 This gives rise to the logical department called 

 the Conversion of Propositions. Affirmative Par- 

 ticular propositions are simply convertible : if you 

 admit that Some A is B, you are bound in con- 

 sistency to admit that Some B is A : if some 

 hasty actions are wasteful, then some wasteful 

 actions are hasty. A Negative Particular Some 

 A is not B commits you to nothing positive 

 beyond itself. Some B, or No B, or All B, may 

 be A, for anything that it implies. A Universal 

 Negative is simply convertible : if No A is B, then 

 No B can be A the two classes are mutually 

 exclusive. A Universal Affirmative All A is B 

 obliges you to admit that Some B is A : but 

 you should be on your guard against admitting 

 that All B is A. 



The conversion of a Universal Affirmative is 

 practically the most important of these cases. It 

 is a very common fallacy to treat the terms of a 

 universal affirmation as if they were simply con- 

 vertible. To take a familiar example : the pro- 

 verb, ' Ill-doers are ill-dreaders,' is often applied 

 as if all ill-dreaders were ill-doers ; and the pro- 

 position that all Protestants exercise the right of 

 private judgment, as if every one that exercises the 

 right of private judgment were a Protestant. 

 (Bain, i. 114.) 



