9 Aug. 1814

Logic

Ch. │ │ Methodization

'. │ │ Subalternation Scale

Division

Definition

5

Take, for example, this definition of the species man. Man is a rational animal. By the word animal indication is given of the larger aggregate within which the aggregate in question, the aggregate indicated by the word man is comprehended. By the word rational is indicated a quality or property which is considered as appertaining at birth at least, and abstraction made of particular accidents, to all individuals comprehended within the name of that lesser aggregate in question, viz. man, and not appertaining to any other individuals comprized within the name of the greater aggregate animal.

But, for this purpose, and on this occasion, and if not antecedently - by this means, here is a larger aggregate psychically or logically divided: divided into two lesser and component aggregates: to the one of these two aggregates application is made of a name: viz. the name man is given: to the remaining aggregate, no name is in and by this same operation, given - it is left without a name. (a)

Note (a) developenda

(a)  Thus by every definition per genus et differentiam a bifurcate division is made: the greater aggregate is divided into two forks or arms. But of that one of the arms to which a name is given, a property, and that a characteristic one, is bought to view: it is thereby placed in the light: whereas of that which constitutes the other arm no such property is brought to view: it is left in the dark.

In a bifurcate division, expressed in the only form in which it is at the same time shewn to be exhaustive, viz. in the contradictional form, both arms are placed, at least as nearly as may be possible in an equally strong light: though of the two arms that which is expressed positively, and that which is expressed negatively, the light in which the former is thereby expressed will naturally be in general the clearer, and thence the stronger.

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