 Seemingly, relations are not jointly instantiated simpliciter; how the instantiation occurs also plays a role. This comes to the fore in particular with non-symmetric relations such as loving. For example, if John loves Mary, then loving is jointly instantiated by John and Mary in a certain way, whereas if it is Mary who loves John, then loving is instantiated by John and Mary in another way. Accordingly, relations pose a special problem: explicating the difference between facts, such as Abelard loves Eloise and Eloise loves Abelard, that at least prima facie involve exactly the same constituents, namely a non-symmetric relation and two other items (loving, Abelard, Eloise). Such facts are often said to differ in “relational order” or in the “differential application” of the non-symmetric relation in question, and the problem then is that of characterizing what this relational order or differential application amounts to.