Editing Substance theory (section)

===Identity of indiscernibles counterargument===

The [[indiscernible|indiscernibility]] argument from the substance theorist targets those bundle theorists who are also metaphysical realists. Metaphysical realism uses the identity of ''universals'' to compare and identify particulars. Substance theorists say that bundle theory is incompatible with metaphysical realism due to the [[identity of indiscernibles]]: particulars may differ from one another only with respect to their attributes or relations.

The substance theorist's indiscernibility argument against the metaphysically realistic bundle theorist states that numerically different concrete particulars are discernible from the self-same concrete particular only by virtue of qualitatively different attributes.

:Necessarily, for any complex objects, <math>a</math> and <math>b</math>, if for any entity, <math>c</math>, <math>c</math> is a constituent of <math>a</math> if and only if <math>c</math> is a constituent of <math>b</math>, then <math>a</math> is numerically identical with <math>b</math>.<ref name="Loux2002"/>

The indiscernibility argument points out that if bundle theory and discernible concrete particulars theory explain the relationship between attributes, then the identity of indiscernibles theory must also be true:
:Necessarily, for any concrete objects, <math>a</math> and <math>b</math>, if for any attribute, Φ, Φ is an attribute of <math>a</math> if and only if Φ is an attribute of <math>b</math>, then <math>a</math> is numerically identical with <math>b</math>.<ref name="Loux2002">{{cite book |first=M.J. |last=Loux |year=2002 |title=Metaphysics: A Contemporary Introduction |series=Routledge Contemporary Introductions to Philosophy Series |publisher=Taylor & Francis |isbn=9780415140348 |lccn=97011036 |url=https://books.google.com/books?id=vgxkGIgPlooC&pg=PA106 |pages=106–107, 110}}</ref>

The indiscernibles argument then asserts that the identity of indiscernibles is violated, for example, by identical sheets of paper. All of their qualitative properties are the same (e.g. white, rectangular, 9 x 11&nbsp;inches...) and thus, the argument claims, bundle theory and metaphysical realism cannot both be correct.

However, bundle theory combined with [[Trope (philosophy)#Trope theory in philosophy (metaphysics)|trope theory]] (as opposed to metaphysical realism) avoids the indiscernibles argument because each attribute is a trope if can only be held by only one concrete particular.

The argument does not consider whether "position" should be considered an attribute or relation. It is after all through the differing positions that we in practice differentiate between otherwise identical pieces of paper.