 when ‘φ’ picks out my body cells and ‘ψ’ expresses the condition ‘less than n+1 nanometers apart from another φ-er’? It may well be that whenever some entities compose a bigger one, it is just a brute fact that they do so (Markosian 1998b), perhaps a matter of contingent fact (Nolan 2005: 36, Cameron 2007). But if we are unhappy with brute facts, if we are looking for a principled way of drawing the line so as to specify the circumstances under which the facts obtain, then the question is truly challenging. That is, it is a challenging question short of treating it as a mere verbal dispute, if not denying that it makes any sense to raise it in the first place (see Hirsch 2005 and Putnam 1987: 16ff, respectively; see also Dorr 2005 and McGrath 2008 for relevant discussion). This is, effectively, van Inwagen's “Special Composition Question” mentioned in Section 4.1, an early formulation of which may be found in Hestevold (1981). For the most part, the literature that followed has focused on the conditions of composition for material objects, as in Sanford (1993), Horgan (1993), Hoffman and Rosenkrantz (1997), Merricks (2001), Hawley (2006), Markosian (2008), Vander Laan (2010), and Silva (2013). Occasionally the question has been discussed in relation to the ontology of actions, as in Chant (2006). In its most general form, however, the Special Composition Question may be asked with respect to any domain of entities whatsoever.