Diairesis

Diairesis (Ancient Greek: διαίρεσις diaíresis, "division") is a form of classification used in ancient (especially Platonic) logic that serves to systematize concepts and come to definitions. When defining a concept using diairesis, one starts with a broad concept, then divides this into two or more specific sub-concepts, and this procedure is repeated until a definition of the desired concept is reached. Apart from this definition, the procedure also results in a taxonomy of other concepts, ordered according to a general–specific relation.

The founder of diairesis as a method was Plato. Later ancient logicians (including Aristotle) and practitioners of other ancient sciences have employed diairetic modes of classification, e.g., to classify plants in ancient biology. Although classification is still an important part of science, diairesis has been abandoned and is now of historical interest only.

Diairesis is Plato's later method of definition based on division, developed in the Platonic dialogues Phaedrus, Sophist, Statesman and Philebus. Further applications are found in the Laws and Timaeus. It is a means of attempting to reach a definition by which a collection of candidates is repeatedly divided into two parts with one part eliminated until a suitable definition is discovered.

A complementary term is merismos (cf. English merism: parsing or the distinguishing of parts, as opposed to diairesis, which is the division of a genus into its parts).

...
Wikipedia