 In order to extend the unionist-separatist classification to metaphysical explanation in general, though, some care must be taken. First (and most obviously), those who believe that there are two or more forms of metaphysical explanation need not be unionists or separatists across the board. The extent to which one is a unionist or a separatist should depend on what non-causal relations one takes statements like (1)–(4) to derive their explanatory power from, as well as on background assumptions about what kind of thing an explanation is and what kinds of things it relates, or even whether these statements ascribe relations at all on the final analysis. For instance, we have spoken loosely of metaphysical explanations as truths of a certain kind that can be discovered and argued over; one might take this view, and add to it the claim that they are truths involving a relation between facts. Such a view might preclude one from being a unionist about, say, essentialist explanations like (3), if one holds that they concern relationships that may involve things that are not facts (e.g., Socrates and his father).