Full Idea
Two different views of logical consequence are necessary truth-preservation (based on modelling possible worlds; favoured by Realists), or truth-preservation based on the meanings of the logical vocabulary (differing in various models; for Anti-Realists).
Gist of Idea
Logical consequence is either necessary truth preservation, or preservation based on interpretation
Source
JC Beall / G Restall (Logical Consequence [2005], 2)
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.7
A Reaction
Thus Dummett prefers the second view, because the law of excluded middle is optional. My instincts are with the first one.