Arguments of this kind reason toward a divine being. The modal-grounding argument reasons toward God as the explanation of modality itself: of why there are necessary truths and real possibilities at all, rather than nothing modal to speak of. Because it leans on the same modal facts the present account is built from, it is the most direct theistic competitor to the book's own grounding of necessity, and it warrants engagement on its own terms rather than as a restatement of the ontological argument [§5.1.7](<5.1.7 Modal Ontological Argument.md>) handles.

The argument's most developed form is Leftow's. Historically, theist modal theories based all necessary truth on God's nature; Leftow (*God and Necessity*(Leftow, Brian, 2012)) argues instead that necessary truths about possible creatures and kinds are fixed by God's unconstrained imagination and choice, with the broadly logical modalities reduced to causal modalities seated in God and events in God's mind. The distinctive move is a *global economy* argument: theists are committed to some theist modal theory, and the explanatory merits of a good one (its economy against the heavy ontologies of Lewisian modal realism and abstracta-laden ersatzism) are offered as an argument for God's existence. Adjacent constructions press the same thought from other directions: Plantinga's suggestion that propositions are best construed as divine thoughts, since there are far more of them than finite minds could entertain ("Two Dozen (or So) Theistic Arguments"(Alvin Plantinga, 2007)); and the theistic activism, or absolute creationism, of Morris and Menzel(Thomas V. Morris and Christopher Menzel, 1986), on which abstracta (modal truths among them) depend for their existence on God's intellectual activity. The shared structure is an inference to the best ground:

1. *Grounding demand.* Modal and necessary facts are real and cannot be brute: they require a ground.

1. *Mind as ground.* A mind is the best or only adequate ground for them.

1. *Conclusion.* A divine mind exists as the ground of modality.

Grant the demand in full. The argument is right that modal facts are not free-floating: that "possibly P" and "necessarily P" cannot be ungrounded surds, true with nothing about Reality to fix them. Grant, too, that a plurality of concrete non-actual worlds (Lewis), or a Platonic heaven of modal abstracta, is a heavy and contestable ontology. The demand for a ground for modality is legitimate, and the dissatisfaction with possible-worlds Platonism is one the present account shares rather than resists.

What the argument adds to that demand is a mind to satisfy it, and the structure satisfies it first. Reality's fixed global domain of real possibility grounds modal status at [§2.1](<2.1 The S5 Pipeline.md>): Modal Stability derives S5 from evaluation over one complete domain W, while the Bottleneck distinguishes that global modality from local reachability. Transition Closure is a narrower auxiliary result concerning onset from capacitylessness, not a third derivation of proposition-wise S5. Modal status is therefore not conferred by an intellect entertaining worlds; it is fixed by the global modal structure the account articulates. The explanatory work Leftow credits to God's imagination and choice, and Morris and Menzel to God's intellectual activity, is already discharged one level down, by the conditions any possibility presupposes. This bears directly on the global-economy form: the theist theory is advanced as the *best* ground precisely because its rivals are taken to be Lewisian realism and abstracta-Platonism. A structural account is a third option that grounds the modal structure without a mind and without a plurality of worlds, so at that level the inference from "best available ground" to God is blocked at the comparative step it depends on.

This front must be drawn at its real scope. What [§2.1](<2.1 The S5 Pipeline.md>) grounds is the modal *structure*: that modal status is determinate, and determined by structure. The modal structure is schematic and existence-silent: it rigidifies what is possible and necessary without settling which contingent things exist or which specific creaturely natures populate the space of the possible. Leftow's theory reaches further than the modal structure, aiming to explain why *these* creaturely kinds are the possible ones. The present account does not, on its own resources, fix that *de re* creaturely content; it fixes the modal structure, not the full roster of what the modal structure permits. A defender can therefore concede that the modal structure needs no mind and still press that the content of creaturely possibility does. Taken alone, this front narrows the argument's reach; it does not close it.

The argument's deeper trouble is independent of how much of modality the structural account claims to ground: the proposed ground cannot do the grounding without carrying a structural burden of its own. A classical divine intellect is typically described as atemporal, non-spatial, and immaterial. The relevant pressure is whether it can bear determinate modal content and stand in an asymmetric grounding relation to possibilities without instantiating at least thin order, difference, and bearing roles. The revised [§5.1.7](<5.1.7 Modal Ontological Argument.md>) verdict does not make the candidate semantically empty by definition; it leaves a substantive grounding burden. Actual finite imagining involves succession, distinction, and persistence, while the classical theorist proposes one timeless intellectual act. Even on that proposal, determinate contents and asymmetric dependence remain. This secures a minimal structural burden; whether it entails the loaded temporal, spatial, and physical types remains disputed.

A defender might relax the ground to an embedded, temporal mind, one that does instantiate the conditions. Then it is no longer the classical God whose aseity the theory was built to secure, and a mind so described instantiates Time, Space, and Substance rather than grounding them: it depends on the structure for its own operation, and so cannot be modality's ultimate ground. The revision keeps a grounder by giving up the ground's ultimacy.

The argument points at something real: modality is not explanatorily idle. The present account locates its modal structure in Reality's fixed global possibility-domain and the structural Conditions later derived for worlds in that domain. The general result of [§4.1.10](<4.1.10 The Source of Possibility.md>) is narrower than an absolute sourcelessness thesis: no candidate whose own status is modal can confer the modal domain it already inhabits. A mind posited as an internal modal item therefore cannot ground W from outside; an essence-prior or transcendent mind remains a further metaphysical posit whose grounding credentials require independent argument.

*What is established.* The modal-grounding argument is right to refuse free-floating modality, and the structural account supplies a non-theistic ground for the global modal domain. That blocks the global-economy inference to God at the comparative step. A classical divine mind stripped of every structural role also fails to supply an intelligible active grounding relation on the present account. A defender may instead posit an essence-prior or transcendent ground, but then the proposal has moved beyond a modal-grounding explanation and owes an independent metaphysics of that ground. What the argument sees — the need for modal explanation — the structure supplies; what it adds — a specifically divine mind — remains unearned by the modal facts alone.


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← [5.1.7 Modal Ontological Argument](<5.1.7 Modal Ontological Argument.md>) | [5.1.9 Transcendental Argument](<5.1.9 Transcendental Argument.md>) →
