CHAPTER IV. 

 DIVISION AND CLASSIFICATION. 



58. GENERAL CHARACTER OF LOGICAL DIVISION. As de 

 finition dealt with the intension, so does division deal with the 

 extension, of concepts and terms. Logical division may be defined 

 as the Analysis of the extension of a more general concept into less 

 general concepts. It is the distribution or splitting up of a class 

 into its sub-classes. It is not the distribution of a lowest sub- 

 c\&ss or species infima into the individuals which constitute the de 

 notation of the latter : this process is called Enumeration. It is 

 only a genus, therefore, that can be logically divided. This genus 

 is called the totum divisum, or totum dividendum, and the consti 

 tuent sub-classes are called the membra dividentia, the dividing 

 members because they embody the generic concept by modify 

 ing it each in a different way. Starting with the generic concept, 

 we trace downwards the various forms or modes in which it is 

 differentiated in the things wherein it is embodied. In order, 

 therefore, to divide a genus into two or more co-ordinate species, 

 we must obviously think of some peculiar modification (of the 

 generic concept) possessed by some members of the genus and 

 not by others, or possessed in clearly and definitely varying 

 degrees by different groups of members of the genus, and make 

 this specific mode the basis of the act or process of division. Such 

 an attribute, thus serving as the reason, or basis, or ground, of a 

 division, is called the Fundamentmn (or Principium) Divisionis. 

 Thus, taking &quot;number&quot; as totum divisum, and divisibility by two 

 as basis of division, we divide numbers into odd and even ; taking 

 &quot;conic sections&quot; as genus, and the direction of the plane through 

 the cone as differentia, we divide conic sections into the ellipse, the 

 parabola, and the hyperbola ; taking &quot; triangles &quot; as totum divisum, 

 we may select equality of length of sides &s fundamentum divisionis, 

 yielding three sub-classes : equilateral, with all three sides equal ; 

 isosceles, with only two sides equal ; scalene, with no sides equal. 



