So I am reading this section on the problem of individuation from Koon's Metaphysics Fundamentals and I came across this text which confused me. Could someone help me understand this material? Here is the following text:
"Classical Bundle Theorists are here faced with what philosophers have called the problem of individuation. The problem of individuation consists in a challenge to identify a constituent of substances in virtue of which two substances are distinct, rather than identical. Since Classical Bundle Theory identifies substances with co-instantiated sets of universals, and since universals are natural properties and natural properties seem to all be shareable, the Classical Bundle Theorist seems to have no way to account for the distinctness of indiscernible substances. However, the problem of individuation is not unique to Classical Bundle Theory. Any Constituent Ontology committed to both PCI and Realism must respond to it. The problem of individuation is related to the Hochberg–Armstrong objection to Extreme Resemblance Nominalism. The reader might recall that the Hochberg–Armstrong objection pressed the Extreme Resemblance Nominalist to find distinct truthmakers for facts of similarity and facts of distinctness. The Extreme Resemblance Nominalist conflates the truthmakers for these types of fact in a problematic way, according to the objection. What we now see is that Classical Bundle Theory is up against a similar problem because they are using the same constituents of substances to account both for similarity and distinctness. The problem of individuation is a challenge to separate the metaphysical ground for similarity facts and distinctness facts."