Is Existential Inertia actually a threat to classical theism? I don’t think so.
In his long post on the Existential Inertia Thesis, Joe Schmid formulates EIT as follows:
>Existential Inertia Thesis (EIT): For each member O of some (proper or improper) sub-set of temporal concrete objects and for each time t such that O exists at some time t* earlier than t, (i) at t, O does not ontologically depend on the existence or activity of some concrete object O*, where O* is not a (proper or improper) part of O, and (ii) if O is not positively destroyed within the temporal interval [t*, t], then O exists at t.
The question is not simply whether this is true, but what it actually excludes. Once the terms are fixed, the supposed conflict with classical theism becomes difficult to sustain.
What is O*?
O is explicitly restricted to temporal concrete objects. O*, however, is left as “some concrete object,” without any temporal qualifier. This creates an ambiguity about the scope of the denial.
If O* is understood as ranging only over temporal concrete objects, then EIT says that temporal objects do not depend on other temporal objects for their persistence. But any thesis that denies only temporal-to-temporal sustaining causes is compatible with classical theism, and more than merely compatible, it is exactly what classical theism would predict. Aquinas argues (ST I, q. 104, a. 1) that created agents within the same order are causes of becoming (causa fieri), not causes of being as such (causa essendi). A builder brings a house into existence, but does not sustain its existence once built. In the same way, no temporal agent accounts for the continued being of another in the relevant sense. So on this reading, EIT does not oppose classical theism at all; it articulates a constraint that classical theism not only affirms but explains.
If, on the other hand, O* is meant to range more broadly so as to exclude any sustaining cause whatsoever, including non-temporal ones, then a further step is required. The issue is not merely how such causes are categorized, but whether there is any justification for extending the domain of O* beyond temporal concrete objects. As stated, no such justification is provided. Without it, the move from “no dependence on external concrete objects” to “no dependence on any sustaining cause whatsoever” does not follow.
As stated, the thesis denies dependence only on “some concrete object O*,” while O itself is explicitly restricted to temporal concrete objects. So the inference from:
- no dependence on other temporal concrete objects
to:
- no dependence on any sustaining cause whatsoever
does not follow unless one first shows that all possible sustaining causes fall within the range of O* as defined. Without that, the exclusion of non-temporal causes is simply asserted, not established.
Can a descriptive thesis rule out divine conservation?
Schmid explicitly presents EIT as a descriptive thesis rather than an explanatory one. It describes how temporal objects persist, not why they persist.
But a purely descriptive account of temporal processes cannot, by itself, exclude a metaphysical explanation of those processes. Divine conservation is not a competing description of what happens within the temporal order. It is a claim about the ground of that order as such.
So even if EIT is correct as a description, it does not follow that divine conservation is false. In fact, a classical theist can accept the descriptive content of EIT and treat divine conservation as the explanation of why that description holds. A description that omits a cause is not evidence that the cause is absent, especially when the cause in question would not appear within the same domain as the description.
The argument only generates a conflict with classical theism if two further steps are taken:
- that the domain of O* extends to all possible sustaining causes, including non-temporal ones
- that a descriptive account of persistence has the explanatory force to rule out metaphysical explanations of that persistence
Neither of these steps is established by EIT itself.
Questions
If EIT is understood as a descriptive thesis about temporal objects, it is compatible with classical theism and can even be explained by it. If it is taken to exclude all sustaining causes whatsoever, then that conclusion depends on additional assumptions about the scope of the quantifier in the thesis and about the reach of descriptive claims.
So the real questions are these: what justifies extending O* beyond temporal concrete objects, and how can a purely descriptive thesis rule out a metaphysical explanation of why that description holds?
Until those are answered, EIT does not do the work it is supposed to do.