Full Idea
The common Rule of Necessitation says that what can be proved is necessary, but this is incorrect if we do not permit empty names. The most straightforward answer is to modify elementary logic so that only necessary truths can be proved.
Gist of Idea
The idea that anything which can be proved is necessary has a problem with empty names
Source
David Bostock (Intermediate Logic [1997], 8.4)
Book Reference
Bostock,David: 'Intermediate Logic' [OUP 1997], p.354