Genus–differentia definition

Proximum genus et differentia specifica is the abbreviated form of scholastic formulation of the classical definition rule " definitio fi ( a) t per genus et proximum differentiam specificam ". This goes back to Aristotle rule according to which a definition has to be done by specifying the next higher genus and specific difference, up to the traditional logic in the 19th century was canonical. Even John Locke (1632-1704), it was not called differently: " [ A] definition must Consist of genus and differentia [. ] "

Genus proximum stands for the "next class " (→ generic term ); differentia specifica of the " peculiar difference " (→ difference in kind ). " Genus " and "species" refers to the pair to be selected generic term / narrower term ( see definition types), and not common in biology technical terms genus and species

Example: The term " person" can be defined as " rational animal ". " Living beings " stands for the parent class: the man is one of the creatures, " rational " for the characteristic difference of all living beings has only man the facility to reason.

In contrast, the definition of man would be as " going on two legs being" inaccurate, namely too far, since not only people, but also birds, unless they move around on the floor, walk on two legs. To narrow the definition of man would be as " states forming beings " because they did not include all the people; because there are people who live in social groups that do not have the character of states. Aristotle's word of man as a political animal is so far not a definition, but a Being description.

It is in this way of defining on the interplay of genus and differentia. What exactly genus proximum and differentia specifica is depends on the universe of discourse and the distribution of the characteristics of the individuals amount to be classified; under certain circumstances, there are several solutions, using the example of man as " featherless bipeds " next " rational animal ". Because in the case where there is no thinking plants, intelligent fungi etc., the difference is enough " rational " way to cut out from the extensive genus " being" a term that includes all humans and only humans.

The classic genre / Artmerkmal definition leads to a hierarchical (s) Classification - or does in advance. This is illustrated in the arbor porphyriana.

Critique of the classical definition rule

Various criticisms have been leveled against this definition rule:

The classic definition rule is still " very useful for many cases [ ... ] " Despite these criticisms as " basic model ".