Full Idea
The Converse Barcan Formula has a startling result. Simple Quantified Modal Logic (SQML) has the following as a theorem: □∀xFx → ∀x□Fx. So 'everything exists necessarily' is a consequence of 'necessarily, everything exists'.
Gist of Idea
The Converse Barcan implies 'everything exists necessarily' is a consequence of 'necessarily, everything exists'
Source
Trenton Merricks (Propositions [2015], 2.V)
Book Reference
Merricks,Trenton: 'Propositions' [OUP 2015], p.65
A Reaction
He says this is blatantly wrong. Williamson is famous for defending it. I think I'm with Merricks on this one.
Related Idea
Idea 19209 Simple Quantified Modal Logc doesn't work, because the Converse Barcan is a theorem [Merricks]