48 THE SCIENCE OF LOGIC. 



terms are used as general and distributive. Still they do not 

 take the indefinite article we do not speak of a water because, 

 although distributive and general in the sense of referring to 

 portions of the whole material, still each portion so referred to is 

 thought of as a collection of homogeneous, uniform, and indefi 

 nitely divisible parts. It is just because of this divisibility that 

 we have no unitary term for the possible ultimate units of such 

 substances, that the ordinary names of such materials are col 

 lective in form, that when we want to refer explicitly to some 

 definite portion of them we have to use such expressions as &quot;a 

 piece of salt,&quot; &quot;some kinds of water,&quot; etc.; whereas when the 

 individuals of a group come clearly before the mind as distinct 

 units it is for them individually we use the principal (unitary) 

 term, e.g. birds, while if we wish to refer to the group we must 

 have recourse to a secondary and derivative (collective) term, e.g. 

 the bird family -, 1 



30. INTENSION AND EXTENSION OF CONCEPTS AND TERMS. 

 There are two kinds of signification or meaning involved in 

 most of our ideas and terms (36). A concept or term applies to or 

 stands for (&quot; supponit&quot; &quot; suppositio &quot; 2 ) an object or class of objects, 

 and it implies certain attributes which those objects possess in 

 common. The relation of the term to the objects indicated by it 

 has been partially examined in the preceding section. There also 

 we saw that a general term is applicable to an indefinite number of 

 objects actual or possible because it implies some attribute (or 

 group of attributes) which they are understood to possess in com 

 mon. This implication of attributes we must now examine more 

 in detail, comparing it with the application of the term to the 

 things possessing the attributes. The latter aspect or reference 

 (the applicational) we propose to call the Extension, the former 

 (or implicational) the Intension, of the term or concept. 3 



31. SUBJECTIVE, OBJECTIVE, AND CONVENTIONAL INTEN 

 SION ; OR, CONTENT, COMPREHENSION, AND CONNOTATION, OF 

 CONCEPTS AND TERMS. These expressions, which are loosely 

 used as synonyms, we shall find it convenient to employ in dis 

 tinct, though allied, senses. For, if we examine the connexion 

 there is between a concept or term and the attributes brought to 



1 VENN, loc. cit. 



2 For history of the term &quot; suppositio&quot; see JOSEPH, Logic, pp. 14, 140. 



3 C/. KEYNES, Formal Logic, ch. ii., whose treatment is largely followed in 

 this section. Other synonyms for Application are Extent, Sphere, Breadth, Scope ; 

 for Implication, Intent, Depth, Force. 



