 In order to understand this characterization, we must first understand Correia’s non-standard conception of modality, inspired by Arthur Prior (1957). Philosophers typically regard possible worlds as giving a complete description of a possible state of the universe. These are what Correia calls globally possible worlds. Locally possible worlds form a broader class. They include all the globally possible worlds, but also strictly locally possible worlds, which are incomplete and do not include facts about certain objects. A strictly locally possible world is “a globally possible world in miniature” (2007, pp. 72–73). Correia suggests that there are strictly locally possible worlds in which there are facts about Socrates but no facts about prime numbers. Thus, it is not locally necessary that Socrates has the property of being such that there are infinitely many primes. Thus, this is not one of Socrates’s essential properties.