Volume 112, Issue 6, June 2015
We sometimes say things like this: “being an animal is part of being a dog.” We associate the part with a precondition for exemplifying the whole. A new semantics for modal logic results when we take this way of speaking seriously. We need not treat necessary truths as truths in all possible worlds. Instead, we may treat them as preconditions for the existence of any world at all. I present this semantics for modal propositional logic and argue that it operates on a more basic level of modal reality than possible world semantics.