Full Idea
Logical necessity is the truth of a sentence by virtue of logical laws or intrinsic conceptual connections alone, and thus true in all logically possible worlds. Put in traditional terms, logical necessity is analyticity.
Gist of Idea
Logical necessity is truth in all logically possible worlds, because of laws and concepts
Source
Robert Hanna (Rationality and Logic [2006], 6.6)
Book Reference
Hanna,Robert: 'Rationality and Logic' [MIT 2006], p.196