In this connexion, two factors are of equal importance: [...] 2. A theory introduces certain premisses concerning which the theoretician knows from preceding experience that they fulfil the conditions for application to certain empirical data. These premisses are of the gratest possible generality and may therefore be able to satisfy the conditions for application to a large number of empirical data. [...] the second [factor] we shall call [...] ‘appropriateness’ [of the theory].
- Hjelmslev (1961), a pag.14