Max Black's two-sphere thought experiment is meant to challenge bundle theory. Why does the experiment pose a problem?
AIt shows that properties can exist without any objects to instantiate them
BIt demonstrates that bundle theory is committed to idealism — objects are just mental constructs
CIf objects are nothing but bundles of properties, then two objects sharing all the same properties would have to be numerically identical — yet there seem to be two distinct spheres
DIt proves that a substratum must exist, because otherwise objects would have no location
Bundle theory identifies objects with their property bundles. Two bundles with identical contents are the same bundle — there is no numerical difference beyond qualitative difference. Max Black imagines a universe with two qualitatively identical spheres: same size, mass, color, and position relative to each other. Bundle theory seems forced to say they are one object. But the intuition that they are genuinely two is strong. This is the problem of the identity of indiscernibles.
Question 2 Multiple Choice
According to bundle theory, what makes a particular object — say, this specific red sphere — the object it is?
AIts bare substratum — a featureless entity that 'owns' and holds together its properties
BIts bundle of co-present properties — redness, sphericality, particular mass, location, etc.
CIts causal history — the chain of events that produced it
DThe universal properties it instantiates, minus any particular instances
Bundle theory holds that objects are constituted entirely by their properties — there is no additional ingredient (no bare particular or substratum) over and above the bundle. The object just *is* the cluster of co-present properties. This is what distinguishes bundle theory from substratum theory, which posits an underlying bearer that is distinct from all its properties.
Question 3 True / False
Bundle theory entails that two objects which share all the same properties are numerically identical — that is, they are actually one object.
TTrue
FFalse
Answer: True
This follows directly from the core claim: if an object just is its bundle of properties, then two bundles with the same members are the same bundle. There is no room for numerical distinction without qualitative distinction. This is the identity of indiscernibles (Leibniz's law in one direction), and it is what makes Max Black's thought experiment a genuine challenge for bundle theorists.
Question 4 True / False
Bundle theory holds that objects are mental or immaterial entities, since it denies that there is a physical substratum beneath the properties.
TTrue
FFalse
Answer: False
Bundle theory makes no commitment to idealism. The properties in the bundle can be entirely physical — mass, charge, spatial extent, etc. Denying the existence of a bare substratum does not mean denying the reality of physical properties. A bundle of physical properties is still a physical object. The theory is about the metaphysical structure of objects (bundles vs. substance + properties), not about whether those objects are mental or material.
Question 5 Short Answer
What is the 'compresence' relation in bundle theory, and why do critics argue that invoking it smuggles the substratum back in under a different name?
Think about your answer, then reveal below.
Model answer: Compresence is the relation bundle theorists invoke to explain what holds properties together into a single unified object — roughly, 'being instantiated together at the same place and time.' Critics argue that if compresence is a relation among properties but is not itself one of the properties in the bundle, then it is a hidden extra ingredient that unifies the bundle. This is structurally the same role that a substratum plays in substance theory — it is the 'glue' that makes a collection of properties into one thing rather than many. If compresence must do that work, bundle theory has not eliminated the substratum; it has renamed it.
This objection reveals a deep tension in bundle theory: either the unifying relation is included in the bundle (making it a property, and raising questions about infinite regress) or it is not in the bundle (making it a non-property unifier, which looks like a substratum). Bundle theorists have developed various responses, but the compresence problem remains one of the central objections in the literature.