 Difficulties emerge with this proposal when we face the question of how to understand consistency of world stories. There are maximal sets of propositions that are not possible worlds because they are not consistent in the relevant sense.  But the relevant sense is not easily defined. Following Adams (1981), we might wish to use the concept of possibility to gloss the notion of consistency: a set of propositions is consistent if and only if those propositions could all be true together.  This returns us to the problem noted in the previous paragraph: it again would turn out that necessarily there are propositions (even in mindless worlds). 