Full Idea
Explaining 'it is possible that p' by saying p is true in at least one possible world doesn't get me very far. If I don't understand what possibility is, then appealing to possible worlds is not going to do me much good.
Gist of Idea
We can't explain 'possibility' in terms of 'possible' worlds
Source
Jennifer Fisher (On the Philosophy of Logic [2008], 06.III)
Book Reference
Fisher,Jennifer: 'On the Philosophy of Logic' [Thomson Wadsworth 2008], p.84
A Reaction
This seems so blatant that I assume friends of possible worlds will have addressed the problem. Note that you will also need to understand 'possible' to define necessity as 'true in all possible worlds'. Necessarily-p is not-possibly-not-p.
Related Idea
Idea 16984 I don't think possible worlds reductively reveal the natures of modal operators etc. [Kripke]