The Bundle Theory (also known as the cluster or collectionist theory) of substance is a theory that states that a substance is, or can be identified with, a collection of non-substantial entities. It stands in direct contradiction to the independence theory of substance, which states that a substance is distinct from its qualities. The bundle theory states that a substance either is or can be reduced to its underlying qualities. For example, an orange could be described as a collection of qualities like (i) a certain shade of orange, (ii) a certain pungent odor, (iii) a certain spherical shape, etc. The two primary ways in which bundle theorists understand substances are eliminativism and reductionism.
An eliminativist bundle theorist (such as David Hume seemed to be) denies the existence of substances altogether. The eliminativist would say that the things that we refer to as substances are nothing more than collections of qualities. That is, the very concept of substance is unintelligible.
The reductionist bundle theorist seeks to reduce the concept of substance to an underlying collection of non-substantial entities. The reductionist does not deny the existence of substances at all. Rather he defines substances as such:
X is a substance if and only if X is a collection of a proper kind of non-substantial entities.
Reductionist bundle theories will be the focus of this post.
Reasons for Accepting the Bundle Theory of Substance
One of the most enduring arguments in favor of the bundle theory of substance stems from the apparent impossibility of describing or conceiving of a substance without also describing or conceiving of its qualities. Bundle theorists state that the concept of a “bare particular” (a substance without properties) is incoherent since is impossible to conceive of such a thing. It should be noted, however, that this is a controversial argument that seems to confuse imagination with conception. It is possible to conceive of something that cannot be imagined. For example, it seems entirely possible to conceive of a completely colorless or invisible object, although it does not seem possible to imagine it (picture it within my mind). It seems ludicrous to assert that because I cannot imagine an invisible object it cannot exist. Likewise, it does not follow that because I cannot imagine a bare particular, it is impossible for one to exist.
Another common justification for the bundle theory is that it is more ontologically parsimonious than any independence theory of substance. Ockham’s Razor states that “all things being equal, one should not multiply entities beyond necessity.” Therefore, it appears to be preferable, if possible, to define a substance by identifying it with a collection of non-substantial entities. However, this motivation does not necessitate the truth of bundle theory, since the bundle theory of substance may be incoherent itself.
Forms of Bundle Theory
As stated above, the bundle theorist defines a substance as a collection of non-substantial entities. But what exactly are the non-substantial entities that are being collected? One reply to this question is that substances are collections of abstract universals. Therefore an apple is a substance because it is a collection of certain properties like redness, juiciness, sweetness, etc. However this sort of bundle theory commits a category error which renders it incapable of explaining substances.
If we understand redness and sweetness as universal properties then we also understand them as abstract entities. Any collection of abstract entities is itself, an abstract entity. However substances are concrete entities. Therefore it is impossible to define any substance as a mere collection of abstract properties.
Another form of bundle theory employs the idea of sets. It is argued that a substance is a set of non-substantial entities. Sets, however, also seem to be abstract entities. At least some sets contain only abstract elements, and since sets are an ontological category which would have to fall into either the concrete or abstract division of entities (the most basic and primary ontological division), it seems that sets should be considered as abstract entities. Therefore, this once again leads to a category error that leaves abstract sets unable to explain the existence of concrete substances.
A final sort of bundle theory states that substances are collections of non-substantial, concrete entities. Thus, since concrete entities are employed in this definition, a category error is averted. There can be two ways of understanding this form of bundle theory: Phenomenalistic Collectionism and Trope Collectionism.
Phenomenalistic Collectionism is a theory that states that a substance is a mereological sum of non-substantial, mind-dependant, concrete qualities. This theory was championed by the idealist philosopher George Berkeley. Berkeley (and possibly Hume) believed that substances were a collection of ideas or impressions. However this theory doesn’t seem to square with everyday, common-sense notions of reality. Since there appears to be no justifiable reason to reject the nearly ubiquitous understanding of the material world, this paper will focus primarily on Trope Collectionism, which is a theory that defines a substance as a collection of non-substantial, mind-independent, concrete qualities or tropes.
Arguments against the Bundle Theory of Substance
One objection that has been raised against the bundle theory of substance is that it seems to imply a form of mereological essentialism. If a substance is a collection of non-substantial tropes, then it seems that if any of these tropes were altered in any way, the substance would be destroyed. Take a particular basketball for example. The bundle theorist would say that this basketball is a collection of certain qualities, such as a particular shade of orange, a particular shape and circumference, etc. However, if one were to paint the basketball white, add more air to it, or deflate it; it would cease to be a collection of those original qualities. Therefore the original substance would have been destroyed. Mereological essentialism is quite a hefty burden for the bundle theorist to bear.
Another objection to bundle theory is that it appears to confuse qualities with parts. We do not intuitively consider the color and circumference of a basketball to be parts of the basketball. We would consider the material constituents of the basketball to be its parts though. However, each item within a collection is a part of that collection. Therefore according to a collectionist theory of substance, not only are the material elements of the basketball its parts, but the qualitative aspects as well (shape, color, size, etc.). The burden of proof as to why the qualitative aspects of an object are indeed parts of an object rests on the shoulders of the bundle theorist.
The arbitrary unity of odd properties poses another problem for the bundle theorist. It is ludicrous to assert that a collection of the sound of a cat, the feeling of a breeze, the smell of onions, and the particular shade of an eggplant would constitute a substance, but it seems that the bundle theorist would be forced to do so. Since the bundle theory of substance states that a substance is a collection non-substantial qualities, it seems that any collection of qualities will suffice. At least it seems that the bundle theorist cannot offer a reason to think otherwise.
This brings us to the final and, perhaps, the most problematic objection to the bundle theory of substance. If a substance is a collection of non-substantial, concrete qualities, what exactly holds these qualities together? Why do we not perceive random qualities “floating about”? Why do they collect into substances?
The bundle theorist can answer this problem in one of five ways.
- (1) The parts of a collection are unified by being in the same place at the same time.
- (2) The parts of a collection are unified due to a causal connection with one another.
- (3) The parts of a collection are unified through a metaphysically necessary connection.
- (4) The parts of a collection are unified through a combination of the above.
- (5) The parts of a collection are unified through some unknown unifying relation.
One problem with (1) is that this explanation denies the possibility of non-physical substances such as souls (or God since he would be considered a soul). The question of whether or not souls exist is not the issue here. Any explanation of a substance should account for actual substances and logically possible substances. The concept of a soul seems to be coherent, therefore this explanation of unity does not allow for the existence of a logically possible substance.
Another problem with (1) is that there is at least one other entity that would fit the definition given. Events, which are certainly not substances, are composed of qualities that are in the same place at the same time. Things like hurricanes and lightning bolts are not substances, yet they fit the explanation given in (1).
It can be objected that (2) implies something similar to mereological essentialism, if the bundle theorists insists that all of the elements within the collection are causally dependent on one another. In this scenario, if one of the elements is destroyed, then all of these elements would be destroyed. A substance would possess all of its properties essentially.
The bundle theorist can respond by stating that (2) does not apply to all of the tropes within the collection, but rather to certain tropes in a certain situation so that if one of them is destroyed, then all of the tropes within the collection will be destroyed. However, Professors Hoffman and Rosenkrantz (Substance Among Other Categories) have supplied a counterexample to this by citing the example of a collection of two china cups (c). In a certain situation, a bull causes one china cup to crash into another, thereby destroying them both. The first china cup loses the particular quality of being at rest on the table which causes the subsequent destruction of all the qualities within c. In this situation, c, would qualify as a substance. Therefore, the revision of (2) does not succeed in explaining how the parts of a collection of qualities are unified.
Objections to (3) would be similar to those of the first form of (2). If there is a metaphysically necessary connection between the parts of the collection, then a substance cannot survive the loss of any of its qualities.
(4) seeks to explain the unification of qualities within a collection by some sort of combination of the previous three explanations. However any combination of the previous three will only be subject to the very same objections which the original constituents garnered. The possibility of souls will always exclude the space and time explanation, the implication of mereological essentialism will crop up in metaphysically necessary connections, and counterexamples like the bull in the china shop used above will defeat the casual interdependence explanations.
A final explanation that can be offered by the bundle theorist is (5), that there is some unknown unifying relation that ties the collection of qualities together. Whether this unifying relation is referred to as “consubstantiation” (Castaneda) or “compresence” (Russell), it is subject to the same criticism: the fact that nothing is known about it leads to the fact that it is either meaningless or question-begging to talk about it.
In conclusion, it may be stated that while the bundle theory of substance offers an attractive simplicity, it simply cannot stand up to analytical scrutiny. It appears to confuse tropes with parts, implies mereological essentialism, and cannot explain why certain qualities are bundled together and how exactly this takes place.