 This is where the appeal to bruteness comes in. Nominalists can say that (a) we can keep giving explanations of the above sort (i.e., explanations of the sort ‘a is F because it is G,’ or because its parts are Gs, Hs, and Is, or whatever) for as long as we can, and (b) when explanations of this sort cannot be given, no explanation at all can be given. The thought here is that at this point, we will have arrived at fundamental facts that do not admit of explanations — e.g., facts about the basic physical natures of elementary particles. When we arrive at facts like this, we will say: “There's no reason why these particles are this way; they just are.”