 According to Lewis [a class nominalist], a property is a set of possible objects. (Something is a property if and only if it is a set all of whose members are possible objects.) The property of being a pig or porcinity, Lewis says, is simply the set of all possible pigs—a set far larger than the set of actual pigs. Consider an actual pig, Freddy. Freddy of course has porcinity. And what is this relation “having” that holds between the pig and the property? Why, simply set-membership. And the relation that a set of possibilia bears to its individual members is certainly not constituency. Freddy is no doubt in some sense a constituent of the set of all possible pigs—‘constituent’ is a very flexible word, and it is probably flexible enough to permit that application —, but there is no conceivable sense in which the set of all possible pigs is a constituent of Freddy. (2011: 392–393)