For bundles of universals can be in more than one place at the same time; so a bundle can have more than one instance; so there can be numerically distinct particulars sharing the same universals; so the principle of identity of indiscernibles is false.

I would say I was a philosophical boy. Thoughts about 'identical stones' are the earliest philosophical thoughts I remember. But when I was a teenager I also thought about the more typical philosophical problems teenagers think about: the existence of god, the objectivity of morality, whether one can know that the external world exists.

For bundles of universals can be in more than one place at the same time; so a bundle can have more than one instance; so there can be numerically distinct particulars sharing the same universals; so the principle of identity of indiscernibles is false.

The huge majority of philosophers seem to think that including impure properties in the range of the quantifiers of the principle would make the principle trivial. I have argued that it does not.

A truthmaker is an entity in virtue of which the proposition it makes true is true. And it is a necessary condition of being a truthmaker (though not a sufficient one) that a truthmaker necessitates the proposition it makes true.

The difference between resemblance nominalism and class nominalism is that the former, but not the latter, brings in resemblance to account for the truthmakers of the propositions in question.

The role of metaphysics in relation to other disciplines, whether philosophical or not and including the natural sciences, is thus a foundational role. Lack of clarity in the concepts of metaphysics implies lack of clarity in other disciplines - both theoretical and practical disciplines - employing those concepts or employing concepts that depend on those of metaphysics.