Bundle Theory
The Basic Problem for a Metaphysical Realist Bundle Theorist
Metaphysical philosophers has done an ontological analysis of some concrete particulars saying that they are wholes made up of fundamental constituents, and have ended with two different positions: the substratum theory and the bundle theory. The substratum theory tells us that a concrete particular is a whole made up of various properties (universals) we associate with the particular, with an underlying subject or substratum that has an identity independent of the properties it has. The particular or substratum is the exemplifier of those properties. The bundle theory says that there are no underlying substrata, and the particulars are constituted by the properties associated with them; they are just 'bundles' of those properties. Empiricists are bundle theorists because they found the idea of an underlying substratum objectable. Austere nominalists are, in some way, substratum theorists since they deny that there are such things as attributes, properties and/or qualities, and the austere nominalists see concrete particulars as unanalyzable entities, as things that have no ontological structure. They also say that a concrete particular can be described in many different ways. For them there's just the concrete particular.
Substratum theorists have been arguing about the fact that the bundle theorist cannot explain whether the fact of the subject-predicate information is true or not. They also say that the bundle theorists are devoted to the truth of a false principle known as the Identity of Indiscernibles (II). This principle tells us that it is impossible for numerically different concrete particulars to have exactly the same properties. Since the substratum theorists say that the Identity of Indiscernibles (II) is false, we can conclude that the bundle theory is false too. Substratum theorists can say that (II) is false because the bundle theorists tell us that familiar concrete objects are constituted completely and exclusively by their attributes or properties. For them concrete objects are nothing more than the concurrent attributes common sense associates with them. But the bundle theorists do not take an analysis of concrete objects to represent a contingent truth, a claim that while it’s true, might have been false. The bundle theorist is committed to the relation between constituents and the wholes they compose. Certain things are constructions out of other more basic things. The constructed items are nothing more than the items that go together to constitute them, we can provide like a ‘recipe’ for complex things by identifying the items that count as their constituents. A requirement for the use of these terms is that no numerically different complex objects have exactly the same constituents. But complete identity in constituents entails numerical identity. This claim represents a totally different principle, the Principle of Constituent Identity (PCI). It’s a principle prevailing the use of the correlative notions of constituent and whole. It is impossible for numerically different objects to have all and only the same constituents, and if concrete particulars are objects whose only constituents are attributes, then it is impossible for numerically different concrete particulars to have all and only the same attributes. The substratum theorist says that it is impossible for numerically different objects to be qualitatively indiscernible; that is to have the same shape, color, weight, size and other attributes. Also they say that the Principle of Constituent Identity (PCI) is a principle that does nothing more than affirms a condition on the use of the terms ‘constituent’ and ‘whole’, and we have no option but to say it’s true. To conclude, the substratum theorist says that the falsehood of (II) shows that the claim of the bundle theorist about the Bundle Theory (BT) is false.
A bundle theorist can say that (BT) and (PCI) are both true, and that it is impossible to be numerically different, yet qualitatively indiscernible objects. They deny that the possibility of qualitatively indiscernible, yet numerically distinct objects shows the falsehood of (II). They will also say that for (II) to be false it must be possible for numerically different concrete objects to have the same attributes. They will claim that numerically different objects are qualitatively indiscernible, and they do not have any attribute in common. If it is impossible for different concrete objects to share any attribute, then (II) is just a consequence of trope theory.
Trope theorists deny that different objects can have numerically the same attribute, but they say that it is possible for different objects to have similar attributes. They believe that the similarity between concrete objects is just a similarity between their attributes. But if we have a qualitative indiscernibility or a complete similarity between two concrete objects, then we have a pair of things such that every attribute of one object is similar to an attribute of the other; we can see this as some kind of cycle. The bundle theorist interpret attributes as the exemplification of a single property, so they must hold the principle that where concrete objects agree in attribute, they have at least one constituent in common, the attribute in question. The bundle theorist claim that (BT) holds the attributes of a concrete object in its constituents and that (PCI) maintains the identity of constituents entail to a numerical identity. The bundle theorist that is a realist must deny that it is possible for numerically different concrete objects to be qualitatively indiscernible. The substratum theorist says that the qualitative indiscernible of numerically diverse objects is possible and infers from this the falsehood of the Bundle Theory (BT).
