The challenge to nominalists is to provide an explanation of facts of a certain kind, namely, predicative facts expressed by sentences of the form ‘a is F’, e.g., the fact that a given ball is red. Now, whenever we are challenged to provide an explanation of a fact, or alleged fact, we have a number options. The most obvious response is simply to provide the requested explanation. But we can also argue that the alleged fact isn't really a fact at all. Or, third, we can argue that the fact in que