Does This Argument Checkmate Skepticism?

The Modal Ontological Contingency Argument

“The fool says in his heart, ‘There is no God.’” — Psalm 14:1

Before diving into the argument itself, there are several key questions that must be asked. If each of these can be answered in the affirmative, the argument that follows is not only valid but logically irrefutable.

Does this argument demonstrate that God is a necessary being?
Does it show that parody objections — such as the “perfect island” — fail because they confuse contingency with necessity?
Does it prove that the opposite of this argument is not “It’s possible that God does not exist,” but rather “It is impossible that God exists”?

These are not rhetorical questions; they are the precise tests by which this reasoning must stand or fall. If the argument that follows satisfies all three, then by the laws of logic and modal necessity, the conclusion — that God exists necessarily — cannot be escaped.

The Argument That Leaves Skeptics No Move Left

For centuries, Christians and skeptics alike have debated the existence of God. The philosophical battlefield is lined with arguments — cosmological, teleological, moral, axiological. Each carries weight. Yet one stands apart for its precision and logical force: the modal ontological argument.

Rooted in St. Anselm’s insight and refined by Alvin Plantinga through the tools of modern modal logic, it reaches a striking conclusion:

If God is even possible, then God is actual.

This is not a rhetorical flourish but the backbone of modal reasoning. The argument does not begin with the assumption that God exists; it begins with the mere allowance that God could exist. From that single premise, necessity and actuality follow. In the end, skeptics are left with only one counter-move — and it is the hardest of all: they must show that God is impossible, that the very concept is incoherent like a “square circle.” Otherwise, the game is over. Checkmate.

Modal Logic in Plain English

Ordinary logic deals with true and false. Modal logic adds another dimension: possible, necessary, and contingent.

Possible – “It might rain tomorrow.”
Necessary – “2 + 2 = 4.”
Contingent – “I’m writing right now.”

To speak clearly about these modes, philosophers use “possible worlds.” Don’t picture sci-fi universes; a “possible world” is simply a complete description of how reality could have been. Some truths, like mathematics, hold in every possible world; others differ.

So what kind of being would God be? If God exists, He is not a contingent object like a rock or a raccoon. He would be necessary — existing in every possible world, dependent on nothing else. The modal argument shows that if God is even possible, He is necessary; and if He is necessary, He is actual.

The Core Syllogism

Plantinga reframed Anselm’s idea into modern form:

It is possible that a maximally great being (MGB) exists.
If it is possible that an MGB exists, then an MGB exists in some possible world.
If an MGB exists in some possible world, then — by definition of maximal greatness — it exists in every possible world.
If an MGB exists in every possible world, it exists in the actual world.
Therefore, a maximally great being (God) exists.

This syllogism is valid under the modal system S5. The only premise open to challenge is (1). Yet the premise is modest: not “God exists,” but merely “God could exist without contradiction.” Grant that, and necessity follows.

The “Impossibility Step”

Between steps (3) and (4) lies a crucial clarification:

If a maximally great being exists in every possible world, then it is impossible for Him not to exist in any world.
Therefore, it is impossible for Him not to exist in the actual world.

That is not an extra premise — it’s simply what “necessary existence” means. If something is necessary, its non-existence isn’t possible. This is the precise moment the argument reaches checkmate.

Why the Reverse Fails

Skeptics sometimes reply, “It’s possible that God does not exist.” But that is not the logical mirror of Plantinga’s claim; it is merely the denial of (1).

The true reverse would be: “It is impossible that God exists.”
That bar is extraordinarily high. It requires proving that the very concept of a maximally great being is self-contradictory — as impossible as a married bachelor. Merely disbelieving, or disliking the idea, will not do.

Unless the skeptic can demonstrate such a contradiction, possibility stands — and if possible, then actual.

The Chess Analogy

Think of chess:
Many moves are possible. You can lose almost everything and still play. You can even win with just a king and a pawn.

But one thing you cannot do is play chess without a king. The king is not one piece among others; he is the condition of the game itself.

Reality is the same. Worlds may vary in countless ways — different stars, creatures, histories — but without the necessary being, there is no “game” at all.

No king, no chess.
No necessary being, no reality.

Why S5 Matters

Plantinga’s argument uses the modal logic system known as S5, which states:

If something is possibly necessary, then it is necessary.

In plain terms:
If it’s possible that God exists necessarily, then God exists necessarily — and therefore actually.

S5 captures metaphysical necessity, the same kind we use in mathematics and logic. In that realm, if a proposition is necessary in any possible world, it is necessary in all.

Skeptics already rely on S5-style reasoning whenever they affirm necessary truths such as “No possible world contains a round square.” To reject S5 here while using it elsewhere is special pleading.

A Simplified Definition of S5

Philosophers often refer to the “S5” system of modal logic, which can sound abstract, but its core idea is straightforward:

If something is possibly necessary, then it is necessary.

In ordinary language:
If it’s possible that something must exist, then it must exist.

S5 assumes that necessity is universal — what is necessary in one possible world is necessary in all.

Applied to this argument:

If it’s even possible that God (a necessarily existing being) exists, then God exists necessarily — in every possible world, including ours.

Greatness vs. Excellence

Plantinga distinguishes between two concepts:

Maximal Excellence — Omnipotence, omniscience, and moral perfection in some world.
Maximal Greatness — Those same perfections in every possible world; hence, necessary existence.

A being with maximal excellence might exist contingently. But maximal greatness means excellence that holds across all possible worlds — and thus necessity itself. This distinction halts parody objections before they start.

Why Parodies Fail

Some critics mock the argument: “Then a maximally great island exists!”

But islands are finite, mutable, and contingent. You can always imagine a better one by adding a palm tree. There is no maximal limit defining “island greatness,” and certainly no path from “best island here” to “island in every world.”

Parodies fail because they attempt to turn a contingent category into a necessary one. God, defined as “that than which nothing greater can be conceived,” is not a member of a genus to which improvements can be added. Maximal greatness admits no “topping.” Hence, parody collapses.

Contingency and Infinite Regress

The modal argument reinforces the classical argument from contingency:

Everything in the universe is contingent.
If everything were contingent, nothing would exist.
Therefore, there must be a necessary being.

An infinite regress of contingent causes could never reach “now.” Imagine trying to count to the present if time stretched back infinitely — you would never arrive. The fact that we are here means the chain must terminate in a necessary source. The modal argument identifies that source as God.

Why God Must Be Necessary

To see why a necessary being is unavoidable, consider:

The Principle of Sufficient Reason (PSR) — Nothing exists without a sufficient reason. Every existing thing must be explained either by the necessity of its own nature (as with mathematical truths) or by something else (as with you and your parents). The universe, filled with contingent entities, requires a terminus — a necessary being to ground all existence.
Contingency Requires a Ground — Rocks, rivers, galaxies, even quantum fields could all have failed to exist. If everything were contingent, nothing would explain why anything exists at all. A necessary being explains itself: its essence is existence.
Maximal Greatness Entails Necessity — To be maximally great is to possess maximal excellence in every possible world. To exist in every world is to exist necessarily.
Scripture Confirms It — God reveals Himself as the One who simply is: “I AM WHO I AM” (Exod 3:14). Christ is described as the Logos “through whom all things were made” (John 1:3) and “in whom all things hold together” (Col 1:17). This is the language of necessity, not contingency.
Alternative Explanations Collapse —
- Infinite regress explains nothing.
- “Brute fact” atheism abandons reason.
- Abstract objects may be necessary but are causally inert.
  The only adequate ground is a necessary, personal being — God.

The Skeptic’s Last Move

At this stage, the skeptic has only one possible move left: to claim that God is impossible. Unless they can prove that the very concept of a maximally great being is incoherent — as self-contradictory as a square circle — the possibility premise stands. And if God is possible, then God is actual.

This is the crushing burden the skeptic must shoulder, and throughout centuries of debate, no one has ever successfully carried it.

Answering Classic Objections

Kant’s Objection: “Existence Is Not a Predicate”

Immanuel Kant argued that existence is not a property that makes something greater, and therefore cannot be part of a definition. But Plantinga’s modal reformulation sidesteps this entirely. The argument doesn’t treat existence as a property (like color or shape); it treats necessary existence as a mode of being.

Just as truths can be contingent or necessary, so too can beings. To deny necessary existence as a legitimate mode of being would undercut mathematics, logic, and even reason itself — since those also exist necessarily.

Dawkins’ Claim: “It’s Just Wordplay”

Richard Dawkins dismisses the ontological argument as mere “wordplay.” Yet modal logic is no parlor game; it’s the same logical framework skeptics use to affirm necessary truths in math, geometry, and science.

To claim it is valid in mathematics but invalid in metaphysics is special pleading. If the structure of necessity works when calculating triangles, it works when reasoning about being.

Logical Positivism: “God-Talk Is Meaningless”

The old positivist claim that religious language is meaningless because it’s not empirically verifiable collapses under the weight of its own standard. The statement “Only what can be verified empirically is meaningful” is itself not empirically verifiable.

The modal ontological argument is rigorously logical, meaningful, and coherent. It operates on the same rational grounds as other accepted branches of abstract reasoning — mathematics, logic, and ethics.

The Omnipotence Paradox

Some object: “Can God create a stone so heavy He cannot lift it?”
This is not a paradox in God’s nature but in language. Omnipotence does not include the power to perform contradictions. God cannot make a square circle, nor can He cease to be God — not because He lacks power, but because such concepts are nonsense.

Omnipotence means the ability to do all things logically possible. That definition coheres perfectly.

Omniscience and Human Freedom

Another objection claims that if God foreknows all things, then human freedom is impossible. But divine knowledge doesn’t cause human actions; it simply knows them.

God’s knowledge is like an infallible mirror — it perfectly reflects what free agents do. Philosophical models such as timeless knowledge or middle knowledge (Molinism) provide ways of understanding how divine omniscience and human freedom coexist without contradiction.

Once again, no impossibility arises.

“This Proves a Greatest Being — Not the Christian God”

Some concede that the argument shows a necessary being, but ask, “Why should that being be the God of Christianity?”

The modal argument, by itself, reaches the conclusion of classical theism: a unique, necessary, omnipotent, omniscient, and morally perfect Creator. From there, historical and evidential arguments — such as the resurrection of Christ, the reality of moral knowledge, and fulfilled prophecy — connect this necessary being with the God revealed in Scripture.

The modal argument doesn’t prove Christianity directly; it establishes the metaphysical foundation upon which Christian revelation builds.

A Second Analogy: The Bridge

Imagine a suspension bridge. Every cable, every beam, every joint is contingent — any of them could fail. If the bridge itself hung from other contingent supports, the whole thing would collapse.

The bridge stands only if anchored to something unmovable.

Reality is like that bridge. Every galaxy, star, and person is contingent. If existence itself is supported only by more contingencies, the whole structure of reality cannot stand. It needs an anchor that cannot fail — a necessary being who holds all things together.

The Knockout Syllogism

The entire argument can be summarized in this final form:

It is possible that a maximally great being (God) exists.
If it is possible, then He exists in some possible world.
If He exists in some possible world, then by definition He exists in every possible world (since maximal greatness entails necessary existence).
If He exists in every possible world, then He exists in the actual world.
If He exists in every possible world, then it is impossible for Him not to exist in any world.
Therefore, God exists necessarily — and actually.

The only way to deny the conclusion is to deny the possibility premise — and to do so, one must show that God is impossible. But no contradiction has ever been demonstrated.

The Principle of Sufficient Reason Revisited

The Principle of Sufficient Reason (PSR) demands that everything that exists must have an explanation, either:

in itself (its own necessary nature), or
in another (something that caused or sustains it).

The universe, filled with contingent entities, cannot be self-explanatory. A “self-caused universe” is a contradiction — something cannot bring itself into being. The only adequate explanation is a being that exists by necessity of its own nature — one whose essence is existence itself.

This principle forms a bridge between contingency and modality. The PSR demands a sufficient ground for contingent existence; the modal argument identifies that ground as necessary. The two converge in God.

The Moral and Rational Ground

Every day, we act as though there are absolute moral truths and rational laws that bind all minds. We do not merely prefer justice; we ought to be just. We do not merely use logic; we must use it. These moral and rational obligations presuppose a source that transcends individual preference or culture.

Matter and energy cannot issue moral commands. Chance cannot obligate the will. The only adequate source for these universals is a necessary moral mind — God.

The Simplicity of the Task

All I need do, then, is show that the existence of God is possible — that the concept of a maximally great being involves no contradiction. And the evidence for that possibility is abundant.

Philosophical and historical arguments alike testify to the coherence of the divine:
the teleological argument from design, the cosmological argument from the universe’s beginning, the moral argument from objective right and wrong, the argument from consciousness, the argument from fulfilled prophecy, and above all, the historical reality of the resurrection of Christ.

Each of these independently supports the possibility of God’s existence; together, they make that possibility overwhelming.

By contrast, the arguments most often raised against God — such as the problem of evil or the hiddenness of God — do not show impossibility. They may raise emotional or philosophical challenges, but they do not demonstrate contradiction.

Suffering and divine hiddenness may challenge belief; they do not refute coherence. Therefore, they cannot disprove the possibility of God — and if God is possible, He is necessary.

The skeptic’s burden, therefore, is not to dislike God or doubt Him, but to prove that God is impossible. And that is a burden no one has ever met.

Scripture and the Structure of Reality

The God reached by modal logic is the same God revealed in Scripture:

Exodus 3:14 — “I AM WHO I AM.” God exists by necessity, not contingency.
John 1:3 — “All things were made through Him, and without Him was not anything made that was made.” The Logos is the necessary ground of all that exists.
Colossians 1:17 — “In Him all things hold together.” God is not abstract but personal and sustaining.
Hebrews 1:3 — “He upholds the universe by the word of His power.”

These are the words of necessity. The metaphysical God of reason is the living God of revelation — the One in whom all worlds, all laws, and all lives find their ground.

The Impossibility Clause and Final Checkmate

Why the Reverse Fails

A common misunderstanding of the modal ontological argument is to assume that its opposite is simply:

“It’s possible that God does not exist.”

At first, that sounds symmetrical — but it isn’t.
The opposite of “possibly necessary” is not “possibly not.” It is “necessarily not.”

Formally, the negation of ◇□G (“It is possible that God necessarily exists”) is not ◇¬G (“It is possible that God does not exist”), but □¬G (“It is necessary that God does not exist”).

This distinction changes everything. Once we define God as a maximally great being — one whose existence would be necessary if real — there are only two live options:

□G — It is necessary that God exists in every possible world.
□¬G — It is impossible that God exists in any possible world.

There is no middle ground, no “maybe” category. Once the concept of a maximally great being is accepted, the logic of S5 allows only necessity or impossibility.

If even one possible world includes God, then by definition He exists in every possible world — including ours. Conversely, if God is impossible, He exists in none.

Thus, the entire question turns on this:

Is God possible or impossible?

The Impossibility Version of the Argument

It is possible that a maximally great being (God) exists.
If it is possible, then such a being exists in some possible world.
If He exists in some possible world, then by definition of maximal greatness, He exists in every possible world.
If He exists in every possible world, He exists in the actual world.
If He exists in every possible world, it is impossible for Him not to exist in any world.
Therefore, it is impossible that God does not exist. God exists necessarily and actually.

This final step clarifies what “necessity” truly entails: not just certainty or high probability, but the impossibility of nonexistence.
If the maximally great being exists necessarily, His absence is not merely unlikely — it cannot be conceived coherently within any possible reality.

The Simplicity of the Theist’s Task

All I need do, then, is show that God’s existence is possible — that the very idea of a maximally great, necessary being contains no contradiction.

And that is not difficult. There are countless arguments that make God’s existence not only possible but plausible:

The cosmological argument — The universe began and must have a cause.
The teleological argument — Design points to mind.
The moral argument — Objective moral law implies a moral Lawgiver.
The argument from consciousness — Mind cannot arise from non-mind.
The argument from fulfilled prophecy — Foreknowledge and fulfillment reveal divine authorship.
The historical evidence of the resurrection of Christ — showing not just possibility but revelation.

Each of these arguments, independently, supports the possibility of God’s existence. And by the rules of modal logic, if God’s existence is possible, then it is necessary.

Meanwhile, the atheist bears a far heavier burden: to show that God’s existence is impossible — that it entails a contradiction like a square circle or a married bachelor. Yet no such contradiction has ever been demonstrated.

The skeptic may object to God morally, emotionally, or personally, but objections like the problem of evil or the hiddenness of God do not prove impossibility. They show discomfort, not incoherence. Evil and hiddenness presuppose moral order and meaning — things that make sense only if God exists.

Thus, the theist’s burden is light: show possibility.
The skeptic’s burden is impossible: show impossibility.
And no skeptic in history has succeeded.

The Chessboard of Reality

Let us return once more to the chessboard analogy that has followed us throughout this argument.

In every possible game of chess, there may be countless moves — variations, sacrifices, creative plays. Queens fall, pawns advance, knights fork, and bishops pin. Yet no matter the game, one rule remains absolute: there can be no game without a king.

The king is not one piece among others. He is the condition of the game itself. Remove him, and the game ceases to exist.

Reality works the same way.
Contingent beings come and go — stars explode, species die, civilizations rise and fall. But the necessary being, the metaphysical King, cannot be removed. Without Him, not only would nothing exist — not even possibility itself could exist.

If God exists in every possible world, His nonexistence is not just improbable — it is impossible.
No King, no game.
No God, no reality.
Checkmate.

Revisiting the Questions

At the start of this study, three questions were proposed — the tests by which this argument must be judged.

Let us now return to them.

1. Does this argument demonstrate that God is a necessary being?

Yes.
The entire modal structure proves that if God is possible, He is necessary. Through the Principle of Sufficient Reason and the argument from contingency, we see that all contingent existence points back to one self-existent cause — a being whose essence is existence. Modal logic then shows that such a being cannot exist contingently or temporarily; His nature requires necessary existence in every possible world, including ours.

Thus, God is not merely a being among others — He is Being itself, the necessary foundation of all that is.

2. Does it show that parody objections fail because they confuse contingency with necessity?

Yes.
The “perfect island,” “maximally great pizza,” and other parodies collapse because they rest on contingent categories— things that can always be improved or that depend on external conditions.
A perfect island could have one more palm tree; a perfect pizza could have one more topping. These concepts admit no ceiling, and none are necessary across all possible worlds.

God alone is defined as “that than which nothing greater can be conceived” — not within a genus, but as the ground of all being. Maximal greatness includes necessity. Parody objects, by nature, do not.

Thus, parody arguments are not philosophical counterpoints; they are categorical confusions.

3. Does it prove that the opposite of this argument must be impossibility, not mere possible nonexistence?

Yes — and this is the critical checkmate.
The argument establishes that the negation of “possibly necessary” is not “possibly not,” but “necessarily not.” In other words, once God is defined as a necessary being, there are only two coherent positions:
□G (God necessarily exists) or □¬G (God is impossible).

There is no middle ground.
If God is even possible, He exists necessarily.
If He exists necessarily, His nonexistence is impossible.

The entire burden of refutation, therefore, falls on the skeptic to prove impossibility — a task that, by the laws of logic and experience, cannot be done.

Final Verdict, Final Version: Irrefutable Logic

All three questions have now been answered in the affirmative.

God’s necessity has been demonstrated.
Parody objections have been shown to fail.
The opposite of the argument has been proven to require impossibility — not mere doubt.

Therefore, by the rules of reason, by the structure of modal logic, and by the principle of sufficient explanation, the conclusion stands:

God’s existence is not only possible — it is necessary. His nonexistence is impossible.

This is not a matter of rhetoric or emotion. It is the inescapable conclusion of logic itself.

The Modal Ontological–Contingency Syllogism

Everything that exists has an explanation for its existence—either by the necessity of its own nature or by dependence on something else (Principle of Sufficient Reason).
1a. Necessary beings exist by the necessity of their own nature—they cannot fail to exist.
1b. Contingent beings exist by something outside themselves—they could have failed to exist.
The universe and everything within it are contingent; they depend on something outside themselves for existence.
2a. The universe began to exist, and anything that begins to exist is not necessary—it could have failed to exist.
2b. The universe could have been otherwise (its physical constants, initial conditions, or even its existence are not logically or metaphysically necessary).
2c. The universe is composed entirely of contingent parts; a collection of dependent things cannot form an independent whole.
Contingent existence cannot be explained by an infinite regress of other contingent causes, because such a regress offers no ultimate ground of being.
3a. An infinite regress of contingent causes would still lack a sufficient reason for why the series exists at all.
3b. Therefore, an ultimate necessary cause is required to terminate the regress.
Therefore, there must exist a necessary being whose existence is self-explanatory and uncaused.
4a. A necessary being exists by its own nature (it cannot not exist).
4b. A necessary being provides the sufficient reason for all contingent reality.
It is possible that a necessary, maximally great being (God) exists.
5a. “Possible” here means metaphysically possible—consistent with logic and the concept of a maximally great being.
5b. The concept of a maximally great being is coherent (omniscient, omnipotent, omnibenevolent) and entails necessary existence.
If it is possible that such a being exists, then He exists in some possible world.
6a. A “possible world” refers to a logically possible state of affairs, not a physical universe.
If a necessary, maximally great being exists in some possible world, then He exists in every possible world.
7a. By the modal principle of S5: if it is possible that God exists necessarily, then God exists necessarily (in symbolic form: ◇□G → □G).
If He exists in every possible world, then He exists in the actual world.
(Our world is one of the possible worlds.)
Therefore, a necessary, maximally great being exists in the actual world.
Because this being is necessary, it is impossible for Him not to exist—His nonexistence is logically incoherent.
10a. Necessity implies non-contingency: it is not possible that God does not exist (¬◇¬G).
10b. Denying the existence of a necessary being entails a logical contradiction once necessity is established.
Therefore, the existence of all contingent reality is grounded in this necessary, self-existent, and maximally great being: as Aquinas would say, “that which we call God.”
11a. This being is both the ontological ground (from modal necessity) and the explanatory cause (from contingency).
11b. Therefore, the necessary being deduced by reason aligns with the God of classical theism—eternal, self-existent, and personal.

For the conclusion to be incorrect, at least one premise must be false. If the premises are true or probably true, the conclusion must be valid. In chess, this is known as checkmate.

References

Anselm of Canterbury, Proslogion
Alvin Plantinga, The Nature of Necessity
Alvin Plantinga, God, Freedom, and Evil
Thomas Aquinas, Summa Theologica
William Lane Craig, The Kalam Cosmological Argument
Immanuel Kant, Critique of Pure Reason
Richard Dawkins, The God Delusion
Robert E. Maydole, “The Modal Perfection Argument,” in The Blackwell Companion to Natural Theology
Alexander Pruss and Joshua Rasmussen, Necessary Existence
The Holy Bible (Exodus 3:14; John 1:3; Colossians 1:17; Hebrews 1:3)