Nominal definition
A nominal definition is the determination of the meaning of a term ( definiendum ) by means of an already known term or several already known terms ( definitions ). Since the Definiendum has the same meaning as the Definiens , one could speak of a tautological transformation. The intention of a nominally defined term describes the set of properties that constitute the meaning of the term. On the other hand, the extension refers to the set of objects that fall under the definition.
Nominal definitions do not contain any empirical information and thus facilitate e.g. B. Discussions about technical jargon . As a result, they cannot be true or false, but rather turn out to be useful / appropriate or unusable / inexpedient in their specific use. They are normative .
The following adequacy conditions apply:
Eliminability: A noun definition must indicate how the newly introduced term can be eliminated from any context in which it may appear grammatically.
Conservativity: A nominal definition must not allow the derivation of new theorems within a theory that could not have been derived from the theory without the nominal definition.
The term goes back to Aristotle . The real definition forms the opposite of the nominal definition .