Abstract
Rather than answering the question "What are possible worlds?", I wish to discuss what I think is a more tractable question, namely, "What what theoretical roles are possible worlds supposed to play, and are they cut out to play those roles?"
The question is tractable because we can simply look and see to what purposes possible worlds have been put and whether possible worlds analyses have survived the test of time, or whether they have been succeeded by superior analyses which either do away with worlds altogether or else demote them to a lesser role. In giving a partial answer to the question, we will begin by looking at traditional possible worlds analyses of intensional and modal concepts (§2). We will then look at three possible worlds analyses that have played an important role in their perceived success, viz. the analyses of (i) modality and possibilities in counterpart theory (§3), (ii) belief contents (§4), and (iii) conditionals (§5).