So I read through this section in Koon's Metaphysics Fundamentals and I didn't fully understand this section, in particular the bold parts of the text where I don't know why Koon's argues in the way that he does. Could someone help me with this? Here is the text:
"Suppose a substrate b has two dimensions of character. (The use of two dimensions of character is incidental, and serves as a simplification. The dilemma would go the same way were the substrate to have three or more dimensions of character.) Either there are tropes or universals that ground b's character or there are not. On the one hand, suppose there are no such properties. Then b seems to be a thickly charactered object, and one will need to appeal to an account of b's character in Class or Extreme Resemblance Nominalist terms, or deny that such an account is needed, in keeping with Ostrich Nominalism. Regardless, one has thereby undercut a central motivation for Realism and Trope Theory. If Realism and Trope Theory are not needed as an account of the thick character of b, then Realism and Trope Theory are needed as a more general account of the thick character of substances. But we only need substrates if Realism or Trope Theory is true. On the other hand, suppose that one does need tropes or universals to ground b's character. Either b's characterizing properties are constituents of b or not. If they are, then one faces the problem of individuation, but for b. Given that we have embraced Substrate Theory, b will itself need a substrate. But this just sets us off down an infinite regress. If b's characterizing properties are not constituents of b, then one has abandoned Constituent Ontology in favor of Relational Ontology. Since Substrate Theory presupposed Constituent Ontology, this view is incoherent. Therefore, b, and substrates generally, cannot have more than one dimension of character."