Full Idea
Unlike Stalnaker, Lewis holds that indicative conditionals have the truth conditions of material conditionals.
Gist of Idea
Lewis says indicative conditionals are truth-functional
Source
report of David Lewis (Counterfactuals [1973]) by Frank Jackson - Conditionals 'Further'
Book Reference
'Blackwell Guide to Philosophy of Language', ed/tr. Devitt,M/Hanley,R [Blackwell 2006], p.224
A Reaction
Thus Lewis only uses the possible worlds account for subjunctive conditionals, where Stalnaker uses it for both. Lewis is defending the truth-functional account for the indicative conditionals.