Full Idea
The semantical notion of a logical truth is that of a valid formula, which is true in all interpretations. In propositional logic they are 'tautologies'.
Gist of Idea
The semantical notion of a logical truth is validity, being true in all interpretations
Source
Theodore Sider (Logic for Philosophy [2010], 2.3)
Book Reference
Sider,Theodore: 'Logic for Philosophy' [OUP 2010], p.33
A Reaction
This implies that there is a proof-theoretic account of logical truth as well. Intuitively a logical truth is a sequent which holds no matter which subject matter it refers to, so the semantic view sounds OK.