Full Idea
I accept the widely held thesis that S5 is the logic of logical necessity.
Clarification
S5 is the most universal of the modal logics
Gist of Idea
S5 is the logic of logical necessity
Source
Ian Rumfitt (The Boundary Stones of Thought [2015], 6.4 n16)
Book Reference
Rumfitt,Ian: 'The Boundary Stones of Thought' [OUP 2015], p.166
A Reaction
It seems plausible that S5 is also the logic of metaphysical necessity, but that does not make them the same thing. The two types of necessity have two different grounds.