  This, in itself, is not an argument against universals per se but only against structural universals. Even so, if a theory of universals must postulate states of affairs, as Armstrong thinks it must, then the argument can be made to work against universals in general. For the state of affairs that Rab (where R is any non-symmetrical relation) necessitates that b exists, which seems to be a necessary connection between wholly distinct existences. And saying that a, b and R are parts of the state of affairs that Rab means trouble if one thinks that no two entities can be composed of exactly the same parts, for the distinct state of affairs that Rba would also be composed of a, b and R. There are two things the defender of universals can do: (a) to accept simple, non-structural universals but reject both structural universals and states of affairs; (b) to accept that some entities can be composed of exactly the same parts (provided they are related in different ways). (b) seems to be more popular among realists about universals. (See Armstrong 1986, Forrest 1986b and Armstrong 1997, 31–38, for further discussion.)