Existential Inertia and Divine Conservation

Most people who believe in creation picture it as something that happened. There was nothing, then there was something, and what followed has been running since. On the classical account this picture is wrong in a way that matters, because creation is not an event in the past that produced a world now standing on its own. It is a relation of dependence that holds at every moment, and if it were withdrawn the world would not fall into ruin or run down. It would simply not be there.

That claim has two parts, and philosophers have separated them. The first is about existence: do things need something to keep them in being, or do they persist by themselves? The second is about action: given that God is doing whatever he is doing at each moment, how much is left for creatures to do? Neither question is settled, and the second has consequences for the problem of evil that the later rungs of this tier will need.

Keeping things in being

Aquinas addresses the first question in the first part of the Summa Theologiae, question 104, asking whether creatures need to be kept in being by God, and answers that they do. His analogy is illumination. The air is lit because the sun is shining on it now, not because the sun shone on it earlier and the light stuck. Remove the sun and the air is dark immediately, not gradually. Creaturely existence, on his account, stands to God's causing it the way the air's being lit stands to the sun's shining.

The reasoning behind the analogy is the act and potency machinery from rung 5. A creature's essence does not include existence: what a horse is does not settle whether any horses are. So a horse's existing at any moment is not accounted for by the horse, and something must account for it. That something has to be at work now, because the fact to be explained is a fact about now.

Descartes reaches a similar conclusion by a different route in the Third Meditation, arguing that the moments of a lifetime are independent of one another, so that what brought him into existence a moment ago does not thereby keep him in existence now, and the same power is required at each instant. The doctrine that results is sometimes called continuous creation, and its strongest versions come close to saying that God creates the world afresh at every moment.

That last formulation is stronger than the tradition needs, and it carries a cost the tradition would rather not pay. If God produces a numerically new thing at each moment, then the thing at this moment is not the thing that was here a moment ago, and what looked like one enduring object is a series of very similar short-lived ones. Persistence has not been explained; it has been replaced by resemblance. Most defenders of conservation therefore insist on a distinction between creating and conserving: creation brings something into being where nothing of that thing was, conservation continues in being what is already there, and the same divine act can do the second without doing the first over and over. Drawing that distinction precisely is harder than stating it, and the difficulty is one of the reasons the inertia debate has been worth having.

A second confusion is worth clearing before the arguments. The conservation doctrine is not the claim that God has to keep deciding not to destroy things. On that picture, annihilation would be the act and continuation the absence of one, which is close to the inertia thesis rather than an alternative to it. The classical claim is the reverse: continuation is the effect of a positive act, and annihilation would require no act at all, being simply what happens when the act is not there.

The rival thesis

The name invites a comparison with the physical principle, and the comparison is doing rhetorical work that should be examined rather than accepted. Newtonian inertia says that a body's state of motion persists absent an external force, and the shift from an Aristotelian physics that required a mover for every motion to a physics that required a cause only for changes in motion was one of the more consequential reversals in the history of science. Defenders of existential inertia are suggesting the same reversal for existence itself. Opponents reply that the analogy is only an analogy: motion is a state a thing is in, and existence is not a state a thing is in but the condition of there being a thing at all.

Edward Feser has pressed the classical case in "Existential Inertia and the Five Ways", in the American Catholic Philosophical Quarterly in 2011, arguing that Aquinas's arguments are, among other things, arguments against inertia, and that the burden falls on the defender of inertia to say what grounds the persistence.

Joseph Schmid and Daniel Linford's Existential Inertia and Classical Theistic Proofs (Springer, 2023) is the most sustained reply, and it is the first book-length treatment of the thesis on its own terms. Their strategy has two parts. The first is to deny that persistence is the sort of thing that requires an external account: on a range of respectable views about time and persistence, an object's existing at a later moment is not a further fact over and above its existing, and demanding a cause for it misconstrues what persistence is. The second is to bring in the philosophy of physics, arguing that relativistic accounts of objects as extended in four dimensions leave no room for the moment-by-moment picture the conservation argument assumes, since on those accounts there are no instants at which a thing must be re-secured.

The classical theist has a response to the second point that is worth stating because it shows how the dispute generalises. If a thing is a four-dimensional object rather than a succession of momentary states, the question does not go away; it changes address. What accounts for the existence of the whole four-dimensional object? The demand for a sustaining cause was never really a demand about instants. It was a demand about anything whose essence leaves its existence unsettled, and a spacetime worm is such a thing as much as a momentary stage is. Whether that response works depends on the premise that every fact has an account, which the third premise of the argument states plainly and which the defender of inertia is free to reject.

What the first-cause arguments were relying on

It would be easy to treat this as a local dispute inside philosophical theology. It is not, because one of the arguments from the intermediate tier depends on the outcome.

The version of the cosmological argument that runs through a causal series per se does not claim that the world had a beginning, and it is not refuted by an infinite past. Its claim is that some causal chains have members whose causal power is borrowed from a member further up, and that such chains cannot be borrowing all the way down. The stock illustration is a hand moving a stick that moves a stone: the stick is not a cause on its own account at all, and if you remove the hand the stone does not keep going with slightly less force, it stops. The argument then holds that a series of that shape must have a first member that is not borrowing from anything, and identifies that member with God.

Everything in the argument turns on there actually being series of that shape. And the chain the argument really cares about is not the hand and the stick, which are only an illustration; it is the chain that sustains a thing in existence right now. If existential inertia is true, that chain has no members. A thing that persists on its own is not borrowing its existence from anything at this moment, so there is nothing that has to be traced upward and no terminus to arrive at. The argument does not get a wrong answer. It has nothing to run on.

This is why defenders of the classical proofs treat existential inertia as a serious threat rather than a technicality, and why Feser's article approaches it as a question about the Five Ways rather than as an isolated puzzle about persistence. The inertia thesis is not a rival conclusion about God. It is a denial of the raw material.

There is a related principle in the background that is worth naming, because it is doing quiet work in the conservation argument. The principle of proportionate causality says that whatever is in an effect must in some way be in its cause, so that nothing can give what it does not have in some form. Applied here, it says that if existence is what is being conferred at each moment, the conferring cause must have existence in a way that does not itself need conferring. That is what rules out an endless chain of sustainers each borrowing from the next, and it is also what forces the terminus to be something whose existence is not distinct from what it is, which is the essence-existence distinction from the previous rungs arriving again by a different road. A defender of inertia does not have to deny the principle. They only have to deny that there is any conferring of existence going on.

How much is left for creatures

The second question assumes an answer to the first. Grant that God is causally at work at every moment sustaining everything. What are creatures then doing?

Alfred Freddoso's "God's General Concurrence with Secondary Causes: Why Conservation Is Not Enough", published in Philosophical Perspectives in 1991, gave the modern discussion its map. The three positions it distinguishes had all been developed in the medieval and early modern period, and the taxonomy has been standard since.

The case for occasionalism

Occasionalism sounds like a curiosity until you see the arguments, which are better than its reputation suggests and which come from two independent traditions.

Al-Ghazali develops one in the seventeenth discussion of The Incoherence of the Philosophers, written at the end of the eleventh century, using the example of fire and cotton. What we observe is that the cotton blackens when the fire touches it. What we do not observe is any power in the fire that necessitates the blackening. All that experience delivers is that the one has always accompanied the other, and constant accompaniment is not necessitation. His theological motive is to leave room for miracles, since a nature that necessitates its effects leaves God no room to act otherwise, but the epistemological point stands on its own. Scholars disagree about whether al-Ghazali held full occasionalism as his settled view or was arguing dialectically against the philosophers, and the argument in the text is stronger than the biographical question.

Malebranche develops the second in The Search after Truth, published in the 1670s. His argument starts from what it takes to be a cause. A true cause, on his account, is one between which and its effect the mind perceives a necessary connection. We perceive no such connection between the fire and the burning, or between my willing to move my arm and my arm moving. We do perceive one between the will of an omnipotent being and what that being wills, since it is incoherent that an omnipotent being should will something and it not occur. So the only true cause is God, and everything else is an occasion.

The line from this to Hume is direct and often remarked on. Hume takes the negative half of the argument, that we never observe necessary connection, and declines the positive half, that God supplies what observation lacks. What remains is the account of causation as constant conjunction plus a habit of expectation that has shaped the subject ever since. Occasionalism is not a dead end in the history of philosophy; it is the road by which the modern problem of causation arrived.

Why most theists reject it

The objections to occasionalism are serious, and the two that matter most are not about science.

The first is about evil, and it is decisive for many. If God is the sole cause of every event, then God is the immediate cause of every act of cruelty, producing the motion of the hand and the state of the mind that accompanies it. The free will defence that the intermediate tier examined requires that creatures do things, and an occasionalist has no creaturely doings to appeal to. Malebranche has resources here, distinguishing what God wills by general volitions expressing simple laws from what God wills particularly, but the resources are strained and the strain is exactly where a critic will apply pressure.

The second is about creatures. A world of things with no powers is a world in which nothing has a nature in any robust sense, since a thing's nature is what it characteristically does. That is a large price for a doctrine of divine sovereignty to charge, and it sits awkwardly with the theological claim that creation is good, since what is being called good has been emptied of everything a thing might be good at.

Mere conservationism avoids both problems and pays elsewhere. Freddoso's title states the charge: conservation is not enough. If God merely keeps creatures in being and then stands back, then the created order is running on its own, and the difference between this and deism is a matter of degree. The concurrentist adds that mere conservationism cannot make sense of God as the cause of everything that happens, since on it there are effects God does not cause but only permits by keeping their causes around.

What concurrentism was built to do

The middle position looks like an evasion until you see the specific job it was designed for, which is the one case where the other two both give the wrong answer.

Consider a sinful act. Mere conservationism handles it easily: the creature does it, God sustains the creature, and God is not the cause of the act. That is comfortable, and the price is that God is not the cause of any act, including the good ones, which leaves the doctrine of providence with nothing to work with. Occasionalism handles it disastrously: God does it, and the creature is the occasion. Concurrentism was constructed to say that God causes the act while the creature causes the wrongness of it.

The scholastic machinery for this turns on a distinction between an act and a defect in an act. The standard illustration is a limp. The power to walk comes from one source and the crookedness of the gait comes from another, namely a defect in the leg through which the power is exercised. Applied to sin, God supplies the being and the activity, and the creature, as a deficient instrument, supplies the disorder. What God concurs in is real; what makes the act wrong is a privation, and a privation is an absence rather than something requiring a cause.

Whether this works depends on the privation account of evil that the intermediate tier introduced, and it inherits every difficulty that account has. If evil is a lack rather than a positive item, no cause is needed for it and the manoeuvre goes through. If some evils are positive states of affairs rather than absences, the defect needs a cause like anything else, and the concurrentist is back where they started with the additional embarrassment of an unused distinction. This is the clearest case in the tier of one doctrine's viability resting on another's, and it is worth carrying forward: the concurrentist account of sin and the privation theodicy stand or fall together.

Concurrentism's general difficulty is the one compromises usually have: saying precisely what the two contributions are and how they combine. If God's concurrence is sufficient for the effect, the creature is idle and we have occasionalism with extra vocabulary. If the creature's power is sufficient, God's concurrence is idle and we have mere conservationism with extra vocabulary. The scholastic answer is that neither is sufficient alone and the effect issues from both, with the creature specifying and God enabling, but a critic will ask what work "specifying" is doing if the specified effect could not occur without a contribution that is not the creature's.

Where the laws of nature fit

Each position implies a different account of what a law of nature is, and the differences show up wherever science and theology are said to be in conflict.

For the mere conservationist, a law describes what creatures do in virtue of the powers they have. The law is about the world, and God's role is to have made things with those powers and to keep them around. This is the account that makes divine action look like an intervention, since anything God does beyond sustaining is something extra done to a system that was managing.

For the occasionalist, a law describes a regularity in God's own volition. Nothing in the fire answers to the law of thermal conduction, because there is nothing in the fire at all; the regularity is God's consistency. Science on this picture is the study of divine habits, and it can be as precise as you like without any creature having a power.

For the concurrentist, a law describes the regular pattern of a joint activity in which creatures contribute the specific character of what happens and God contributes what makes any happening possible. The important consequence is that the two contributions are not competitors. They are not two causes of the same kind dividing the work between them, so that more of one means less of the other. They operate at different levels, and an exhaustive account at the creaturely level leaves the divine contribution untouched.

That last point is the classical theist's standard answer to the charge that science has been steadily crowding God out. The charge assumes that God and natural causes occupy the same explanatory space, which is the assumption a God of the gaps argument makes and which concurrentism denies from the outset. A complete physics of combustion does not reduce God's involvement in a fire, on this view, any more than a complete account of the ink on a page reduces the author's involvement in the sentence.

The reply is good and it has a price that its users do not always acknowledge. A doctrine on which no possible scientific result could count against divine activity is also a doctrine on which no scientific result can count for it. That matters directly for rung 1: a Bayesian natural theology needs the evidence to be more likely on theism than on its denial, and a conception of divine action pitched at a level where the observable facts come out the same either way delivers a likelihood ratio of exactly one. The classical theist can accept this, since natural theology on the classical account was never supposed to run on empirical likelihoods. Anyone who wants both the immunity and the evidential argument is trying to have it both ways.

Next

The two questions in this rung concerned God's causal relation to things and to events. The next concerns God's cognitive relation to events that have not happened yet. If God knew a thousand years ago what someone would do today, then it was true a thousand years ago that they would do it, and it is difficult to see what is left of their being able to do otherwise. The problem is old, the proposed solutions are numerous, and each one costs something that a different part of the doctrine wanted to keep.