Full Idea
Some philosophers say that modal facts cannot be expressed either by name/predicate language, or by first-order predicate calculus, or even by second-order logic.
Clarification
'Modal' facts concern possibility and necessity
Gist of Idea
No sort of plain language or levels of logic can express modal facts properly
Source
Joseph Melia (Modality [2003], Ch.2)
Book Reference
Melia,Joseph: 'Modality' [Acumen 2003], p.21
A Reaction
If 'possible' were a predicate, none of this paraphernalia would be needed. If possible worlds are accepted, then the quantifiers of first-order predicate calculus will do the job. If neither of these will do, there seems to be a problem.