Full Idea
Instead of regarding counterfactuals as conditionals restricted to a range of possible worlds, we can define the necessity operator by means of counterfactuals. Metaphysical necessity is a special case of ordinary counterfactual thinking.
Gist of Idea
Rather than define counterfactuals using necessity, maybe necessity is a special case of counterfactuals
Source
report of Timothy Williamson (Modal Logic within Counterfactual Logic [2010]) by Bob Hale/ Aviv Hoffmann - Introduction to 'Modality' 2
Book Reference
'Modality', ed/tr. Hale,B/Hoffman,A [OUP 2010], p.10
A Reaction
[compressed] I very much like Williamson's approach, of basing these things on the ordinary way that ordinary people think. To me it is a welcome inclusion of psychology into metaphysics, which has been out in the cold since Frege.