DIVISION AND CLASSIFICA TION. 1 2 1 



classes of things existing in the world around us, and expressed 

 by the common names of ordinary language, is not at all so easy 

 a matter. It is in fact an ideal which can at best be only imper 

 fectly realized. Our success in making an exhaustive division 

 of any given genus, politicians, for example, or styles of archi 

 tecture, will depend upon the extent and minuteness of our in 

 formation about these departments. Any attempt to divide such 

 classes into their real sub-classes as distinct from mere hypothe 

 tical, fanciful sub-classes will show us at once how such division 

 is dependent on material considerations, on our knowledge of 

 matters of fact. 



RULE III. If each genus be not divided into its proximate 

 species, some intermediate species may be omitted, thus making 

 the division too narrow. Thus, if I attempt to divide rectilinear 

 plane figures immediately into such remote species as equilateral 

 triangles, squares, parallelograms, pentagons, etc., I am running 

 considerable risk of omitting one or more sub-classes. If I give 

 one or more proximate species, e.g. triangles and polygons, simul 

 taneously with one or more remote species, e.g. parallelograms 

 and squares, I am making a disparate division, which is pretty 

 sure to be confusing even when it is not also inaccurate. 



63. &quot;MATERIAL&quot; DIVISION OR &quot; CLASSIFICATION &quot;.Let US 

 now turn from the purely formal aspect of logical division (61), 

 and inquire how we are to put its principles into practice, 

 how we are to group together logically the objects which 

 form the material of, all our knowledge, and thus introduce order 

 and clearness into our ideas. 1 We may say at once that this is 

 already done for us at least in a rough and ready way in the 

 language we possess. 2 The formation of the common names of 

 ordinary language has involved in it generalization, grouping, 

 classification. The chaotic mass of data revealed to us in sense 

 experience furnishes the raw material for the problem of Classi- 



*It must be borne in mind that all logical division is a mental analysis, an 

 arrangement of our ideas according to their greater or lesser extension. Even when 

 an actual arrangement of objects (in space) or of their names (in a catalogue) results,! 

 a sit often does, from the mental process, it is this latter alone we call logical division. 



2 &quot; Ages before the logician or anyone else who deals with systems, had a hand 

 in the matter, the necessities of common life had been at work prompting men to 

 group the things which they observed. All names imply the recognition of groups, 

 and a great number of names imply a subordination of groups, so that at the earliest 

 stage to which we can transfer ourselves we find that we are already in possession 

 of a rudimentary classification ; and that we cannot even talk or think about things, 

 without an appeal to this.&quot; VENN, op. cit. t p. 322. 



