11. SUMMARY.
(1) Logical division is the process of separating a proximate genus into its co-ordinate species.
(2) The first subdivision in a logical division gives class terms, while the first subdivision in an enumeration gives individual objects.
(3) Partition is the process of separating an individual thing into its parts. These parts may be either quantitative or qualitative.
A logical division of any genus may be summarized in a series of judgments of which a species is the subject and the genus is the predicate.
(4) The four rules of logical division are: the division must (1) be based on one principle, (2) have species mutually exclusive, (3) be exhaustive and (4) proceed from proximate genus to immediate species.
A violation of the first rule gives a cross division.
Exhaustive division is easily confused with a complete or finished division.
(5) Dichotomy is a continual division of a genus into two species which are contradictory in nature.
An historical illustration of dichotomy is the Tree of Porphyry.
Dichotomy is of service in the field of new and unexpected discoveries.
(6) Classification is the process of grouping notions according to their resemblances or connections.
Classification is inductive in nature, division deductive. Classification unifies, division differentiates.
(7) An artificial classification is made on the basis of some arbitrary connection; a natural classification, on some inherent mark of resemblance.
(8) The rules of logical division are applicable in any classification. In addition to these a classification should (1) be appropriateand (2) afford opportunity for the greatest possible number of assertions.
(9) Classification should be the mode of procedure in the lower grades, division in the higher grades.