122 THE SCIENCE OF LOGIC. 



fication. Given the whole, or a more or less extensive portion, 

 of that material the universe of living things, for example the 

 problem of classification is to arrange (our ideas of) the things l 

 which constitute this universe into a regularly related hierarchy of 

 coordinate and subordinate groups of classes. When we have 

 apprehended the extent and boundaries of our territory, we may 

 either begin above by some great, broad division of the whole 

 into a few departments into plants and animals, for example, 

 and then, by subdivision of these, proceed gradually downwards 

 towards the lowest and narrowest classes discernible ; or, without 

 looking first for any great line of division suggested by a view 

 of the whole field, we may begin below with some of the narrowest, 

 most obvious, and most clearly marked, groups that may happen 

 to fall under our notice robins, potatoes, greyhounds, oak-trees, 

 human beings, or the like and proceed upwards gradually by 

 a process of aggregation of larger and larger groups, until we have 

 exhausted the whole sphere of living things ; 2 or, finally, we may 

 combine the upward and the downward processes, working as 

 best we can in both directions. But, wherever we begin, one 

 thing is perfectly clear, namely, that even supposing the group 

 to be divided, the summum genus as it is often called (living 

 things), and all the lowest groups or infimae species (daisies, 

 rabbits, wasps, herrings, etc.), to be given us in the very language 

 we use, as data, as fixed groups, still between these lowest and 

 the one highest class there will be practically endless ways of 

 framing and arranging the intermediate classes : plants, for in 

 stance, will be classified very differently by the physician, the 

 agriculturist, and the botanist. From which we infer that our 

 system or hierarchy of classes will depend on the attributes we 

 choose as grounds of our divisions. 



64. ITS GROUNDS DETERMINED BY ITS PURPOSE : THIS EITHER 

 4 GENERAL &quot; OR &quot; SPECIAL &quot; : HENCE &quot; NATURAL &quot; AND &quot; ARTI 

 FICIAL&quot; CLASSIFICATIONS. Hence arises the question : How, in 

 classification, are we to determine our fundamenta divisionis ? 

 What considerations ought to influence us in our selection? 

 Needless to say, logic cannot tell us what attributes, as grounds 



1 Or events, as the case may be : the problem of classifying natural events or 

 phenomena is by way of discovering their natural causes, the laws according to 

 which they take place : which is the main problem of physical induction. 



2 &quot; In the physical process of sorting shot or gravel into a number of packets ac 

 cording to size, it would come to the same thing in the end whether we made use 

 of the sieves by beginning with the finest or with the coarsest.&quot; VENN, ibid. 



