6.1231 The mark of a logical proposition is not its general validity.

To be general indeed means only: to happen to be valid for all things. An ungeneralized proposition can indeed be just as tautologous as a generalized one.

Cf. 6.031 on kinds of generality. Is there a contradiction here? Or in 6.1231 is "general" being used in a particular sense, distinct from, say, necessary or a priori?