What is the "existential inertia" argument in contemporary naturalistic philosophy, and does it succeed in refuting the Thomistic arguments for divine conservation of the world?

This question addresses one of the most recent and profound debates in contemporary analytic metaphysics: Do material things need an external cause to continue existing moment by moment (divine conservation), or do they possess "existential inertia" that makes them continue existing by themselves? The debate places classical Thomistic metaphysics in direct confrontation with contemporary naturalism.

Inadequate Responses to Avoid

From some defenders of theism:

"Things need God to continue existing; this is self-evident." This claim requires philosophical justification. What seems "self-evident" to some may not be so to others. Intuition alone is insufficient in a technical metaphysical debate.

"The Qur'an is clear: 'And it is He who withholds the heaven from falling upon the earth.'" This is textual reasoning in a philosophical context. Philosophical debate requires rational arguments, and religious texts are interpreted in light of philosophical data, not vice versa.

"Without God, everything would collapse immediately." This begs the question. This is precisely what needs to be proven, not assumed. The naturalist claims that things do not collapse but continue through their existential inertia.

From some naturalists:

"Modern physics has proven the conservation of matter and energy." This confuses levels. The law of energy conservation describes how matter and energy transform, not why they exist in the first place or continue to exist. The metaphysical question is deeper than physical description.

"The idea of divine conservation is a remnant of medieval thinking." This is historical rejection. The age of an idea does not determine its truth. Many ancient ideas (like atomism) proved correct, and many modern ideas proved false.

"If God conserves everything, who conserves God?" This misunderstands the argument. The Thomistic argument distinguishes between existence per se (God) and existence per aliud (creatures). The question only applies to contingent beings.

Why These Responses Are Inadequate

They share a common failure to engage with the precise logical structure of the debate. The issue is not intuitive, textual, or purely scientific, but metaphysical, requiring careful conceptual analysis of existence, persistence, and causation.

The Thomistic Argument for Divine Conservation

Thomas Aquinas and his contemporary followers (Edward Feser, David Oderberg) present a multi-stage argument:

Stage One: The Distinction Between Essence and Existence
In every contingent being, essence (what the thing is) is distinct from existence (that the thing is). Being "human" or a "tree" does not include existence in itself. Existence is "added" to essence.

Stage Two: Existence Requires Continuous Explanation
If existence is not included in essence, then the thing does not possess its existence by itself. What does not possess something by itself needs an external source for it. This need is continuous, because the separation between essence and existence is continuous.

Stage Three: Simultaneous Causal Series
Preserving existence requires a simultaneous causal series (per se), not a successive one (per accidens). For example: the hand moves the stick which moves the stone—all movements are simultaneous. This series must terminate in an unmoved first mover.

Stage Four: Existence Per Se
The series terminates in a being whose existence is identical with its essence—God in the Thomistic conception. This being needs no external conservation but conserves all other beings.

The Counter-Argument of Existential Inertia

Contemporary naturalistic philosophers (Graham Oppy, J.L. Mackie, Paul Edwards) developed the "existential inertia" argument as a direct response:

Basic Claim: Just as moving bodies continue in motion unless stopped (Newton's first law), existing bodies continue to exist unless destroyed. Continued existence is the "default" state that requires no special explanation.

Argumentative Structure:
1. Our empirical observation: Things naturally continue to exist
2. Principle of economy (Occam's Razor): We don't assume additional causes without necessity
3. There is no logical necessity to assume an external "conserver" of existence
4. Therefore: Things possess inherent existential inertia

Contemporary Development:
Benoît Dhonte in "Why Would Anything Remain in Existence?" (2021) provides a refined formulation: The need for explanation is not for continuation but for change. If something exists at t1, the natural assumption is that it will exist at t2 unless a changing factor intervenes.

Contemporary Thomistic Critique of Existential Inertia

Edward Feser in "Existential Inertia and the Five Ways" (2011) presents a multi-front critique:

First: Confusing Types of Change
Inertia in physics concerns spatial motion, which is an accident. Existence is not an accident but the fundamental condition for all accidents. The analogy between them is a category mistake.

Second: Experience Does Not Prove Existential Inertia
Our observation that things "continue" does not tell us whether they continue by themselves or through external conservation. Experience is neutral between the two explanations. The claim that experience supports existential inertia goes beyond what experience actually says.

Third: The Problem of Mereological Composition
Material things are composed of parts. What preserves the unity of composition? If each part has its independent existential inertia, what prevents the parts from disintegrating? Unity requires an external unifying principle.

Fourth: The Problem of Powers and Dispositions
Material things have powers and dispositions. An electron "tends" to be attracted to a proton. These dispositions need continuous "actualization." What keeps these powers active?

Naturalistic Responses to Thomistic Critique

To the First Critique: The distinction between motion and existence is artificial. Both are states of the physical system. If the system has inertia in one state (motion), why not in another (existence)?

To the Second Critique: True that experience is neutral, but the principle of economy favors the simpler explanation. Assuming an invisible external conserver adds unnecessary complexity.

To the Third Critique: Mereological unity can be explained by natural forces (chemical bonds, nuclear forces). No need for an external metaphysical unifying principle.

To the Fourth Critique: Powers and dispositions are part of things' natures. The electron doesn't "choose" attraction; this is part of its essence. No need for external "actualization."

Latest Developments in the Debate

From the Thomistic Side:
- Gaven Kerr in "Aquinas and the Metaphysics of Creation" (2019) develops a precise distinction between existence as "act" (actus essendi) rather than mere "fact"
- Timothy Kearns uses contemporary powers ontology to deepen the critique

From the Naturalistic Side:
- Joseph Schmid in multiple papers (2021-2023) develops a detailed defense of existential inertia, with responses to all of Feser's objections
- Daniel Linford uses models from quantum physics to support the idea of self-persistence

The Deeper Philosophical Point

The debate reflects a deeper disagreement about the nature of existence itself:
- The Thomistic View: Existence is a continuous "gift," and things "participate" in divine existence
- The Naturalistic View: Existence is a state or property, and things "possess" their existence

This fundamental ontological disagreement makes final resolution difficult, as each side starts from different metaphysical intuitions.

Intersections with Other Debates

The debate intersects with:
- The Cosmological Contingency Argument: If things have existential inertia, is the universe as a whole necessary?
- The Problem of Personal Persistence: What preserves personal identity through time?
- Philosophy of Time: Is time substantival or relational?

From the Perspective of Rational Probability

The existential inertia argument poses a serious challenge to Thomistic arguments, but does not definitively refute them:

Where We Stand in This Debate Today

The debate over existential inertia has witnessed notable acceleration in analytic academic production since 2020. Joseph Schmid has become the foremost authority in defending existential inertia, having published a series of papers between 2021 and 2023 that systematically dismantle Feser's objections one by one, and developed a model distinguishing between "strong existential inertia" (things cannot cease to exist without cause) and "weak existential inertia" (insufficient evidence for needing a conserver). Meanwhile, Gaven Kerr and Timothy Kearns have deepened the Thomistic side using powers ontology, which is growing in analytic philosophy and was a tool unavailable to Aquinas himself. Daniel Linford opened a new front by connecting the debate to quantum field physics, suggesting that the structure of quantum vacuum supports the model of self-persistence. However, Thomists responded that the quantum field itself is a contingent being requiring explanation for its existence. The debate remains unresolved, but has moved from the margins to the forefront of analytic philosophy of religion, forcing both sides to refine their conceptual tools in unprecedented ways. The current state is one of genuine dialectical balance, where neither side possesses a definitively decisive argument, and this itself is a philosophical datum worthy of reflection.