 Lewis (1986: 62) then adds: “Then we can go on to say that an intrinsic property is one that can never differ between duplicates.” This requires subcosmic objects to bear perfectly natural (/fundamental) properties. Otherwise it will be (vacuously) true, for any two subcosmic objects, that Lewis’s two conditions for duplication are satisfied: these objects and their parts will have no perfectly natural properties whatsoever and a fortiori cannot differ in this  respect.[58]