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.