The Argument from Contingency: Why a Necessary Being?

The argument from contingency holds that everything in the universe, and the universe as a whole, could have failed to exist and does not explain its own existence, so its existence points beyond itself to a necessary being: one that cannot fail to exist, because it exists from itself. Classical theists call that being God. The Many Beings books add a further result: the universe is finite precisely because it is contingent.

Key takeaways

• The argument from contingency reasons from things that could have failed to exist to a being that cannot.
• It has three classic forms, Aquinas's, Leibniz's and William Lane Craig's, and none needs the universe to have had a beginning.
• The contested ground is the principle of sufficient reason and the identification of the necessary being, where Hume, Kant, Russell and van Inwagen press.
• Aseity settles the identification: a self-existent being has no rival, is not a quantity, and explains a contingent world by choosing it.
• Frame-Indexed Classical Theism (FICT) grants classical theism its God beyond every series and theistic personalism its God who chooses, and adds that the universe is finite because it is contingent.

What is the argument from contingency?

A contingent being is one that exists but could have failed to exist: it does not contain the reason for its own existence within itself. A necessary being is one that cannot fail to exist, because the reason for its existence is its own nature. The tradition's word for that condition is aseity, from the Latin a se, "from itself." Among the cosmological arguments, which reason from the world's existence to its source, this one starts from the question Leibniz asked, as Craig quotes him: "The first question which should rightly be asked is, 'Why is there something rather than nothing?'"

The engine of the argument is the principle of sufficient reason (PSR): every contingent thing has an explanation of its existence. Leibniz applied it to every fact; most defenders now need it only for contingent things. Grant it, and a chain of contingent things, however long, cannot be explained by its own members, because each borrows its existence from another. Something that does not borrow must stand behind the whole.

It is the oldest road Christian thinkers took toward the attributes of God: necessity first, then what follows from it. Paul took the same road at the Areopagus, before Stoic and Epicurean philosophers, when he described the Maker on whom every life depends: "For in him we live and move and have our being. As some of your own poets have said, 'We are his offspring'" (Acts 17:28). He argued from dependence, not from a first moment.

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How did Aquinas state it? The Third Way

Thomas Aquinas gave the argument its classic Christian form as the third of his Five Ways in the Summa Theologiae (I, q. 2, a. 3): "The third way is taken from possibility and necessity." In steps:

1. Some things can be and not be, since they come into being and pass away.
2. If everything were possible not to be, then at some time there would have been nothing.
3. Had there ever been nothing, nothing would exist now, since what does not exist begins only through something already existing.
4. Something exists now; so some necessary being exists.
5. Every necessary being has its necessity either from another or of itself, and there can be no infinite series of the first kind.
6. Therefore there is "some being having of itself its own necessity, and not receiving it from another, but rather causing in others their necessity. This all men speak of as God."

The first stage reaches some necessary being (Aquinas allowed created things that cannot corrupt, as his cosmology held of the heavenly bodies). The second reaches the one being whose necessity is underived, which Thomist readers treat as the heart of the proof.

The weakest step is premise 2: that each thing can fail at some time does not obviously mean all could fail at once, and critics have long called it a logical slip. The second stage does not depend on it, and Leibniz's form drops it. Nor was Aquinas arguing that the world began: "By faith alone do we hold, and by no demonstration can it be proved, that the world did not always exist" (I, q. 46, a. 2). The Third Way was built to bind even a world without a beginning.

Volume One lays the foundations of the position, and it is free to download.

What is the Leibniz cosmological argument?

Gottfried Wilhelm Leibniz, among the Christian philosophers of early modern rationalism, removed time from the argument. In the Theodicy (1710), §7, he observes that the things we see and experience "are contingent and have nothing in them to render their existence necessary." Therefore, he concludes, "one must seek the reason for the existence of the world, which is the whole assemblage of contingent things, and seek it in the substance which carries with it the reason for its existence, and which in consequence is necessary and eternal." In steps, the Leibniz cosmological argument runs:

1. Every contingent thing, and every assemblage of contingent things, has a sufficient reason for its existence.
2. The world is the whole assemblage of contingent things.
3. The sufficient reason for that whole cannot lie in any contingent thing, since each is a member of it.
4. Therefore it lies in a substance that carries the reason for its existence in itself: a necessary being.

Leibniz went further. "Moreover, this cause must be intelligent," he continues, because the existing world is one among "an infinity of other worlds being equally possible," and settling on one of them takes an understanding that holds the possibilities and a will that chooses among them. In summary: "Its understanding is the source of essences, and its will is the origin of existences."

The Leibnizian cosmological argument needs no claim about the past. Its weak point is premise 1, which applies the PSR to collections as well as members and so invites Hume's objection.

Creation as the free decree of a changeless God is the subject of Volume Four.

How does William Lane Craig formulate the contingency argument?

William Lane Craig has carried the argument to a general audience, and his form runs:

1. "Every existing thing has an explanation of its existence, either in the necessity of its own nature or in an external cause."
2. "If the universe has an explanation of its existence, that explanation is God."
3. "The universe is an existing thing."
4. "Therefore, the explanation of the existence of the universe is God."

His defence of premise 1 is careful. A ball found in the woods would need explaining, and enlarging it to the size of the universe changes nothing: "Merely increasing the size of the object does nothing to provide or remove the need for an explanation of its existence." To exempt the universe alone commits what he calls "the taxicab fallacy": dismissing the principle once it has carried you where you wanted. Nor does the principle exempt God: "Leibniz does not exempt God from the principle of sufficient reason." God is explained by the necessity of His own nature.

The second premise, he notes, is logically equivalent to the atheist's usual claim that if atheism is true, the universe has no explanation. The cause of all space-time and matter-energy cannot lie within it, and abstract objects stand in no causal relations, so the explanation is "a necessary, uncaused, timeless, spaceless, immaterial, personal being."

Craig's intuitions are right at every point the contingency argument needs. What his form leaves open is the passage to "exactly one," and to "personal" in a sense that does not make God one more agent among agents.

Volume Five meets Craig with gratitude and one located disagreement; see the volume's page.

How is it different from the kalam cosmological argument?

The kalam cosmological argument, Craig's better-known argument, runs: whatever begins to exist has a cause; the universe began to exist; so the universe has a cause. The argument from contingency runs: whatever exists contingently has an explanation; the universe exists contingently; so it has an explanation in a necessary being. The kalam needs a finite past and a causal principle. The contingency argument needs no beginning at all, only the principle of sufficient reason. An eternal universe would defeat the kalam's second premise and leave the contingency argument untouched.

Whether a beginningless past is possible turns on the actual infinite, and that question belongs to Volume Five, Resolving Potential vs Actual Infinity. Its result in one sentence: Craig is right that creation contains no completed actual infinite and right that God's infinity is not a quantity, and the first conclusion rests more securely on aseity than on the paradoxes of Hilbert's Hotel.

The beginning of time has a chapter of its own in Volume Three.

What are the strongest objections to the argument from contingency?

The serious objections to the argument from contingency press on the principle of sufficient reason or on the identification of the necessary being. Here are the five strongest, each with its best reply and that reply's cost.

Isn't it a fallacy of composition? (Hume)

David Hume's Dialogues Concerning Natural Religion (1779), Part IX, gave the objection its classic form, as the Stanford Encyclopedia quotes it: "Did I show you the particular causes of each individual in a collection of twenty particles of matter, I should think it very unreasonable should you afterwards ask me what was the cause of the whole twenty. This is sufficiently explained in explaining the parts." Bertrand Russell sharpened it in his 1948 BBC debate with Frederick Copleston: "Every man who exists has a mother," yet it does not follow that "the human race must have a mother"; that, he said, is "a different logical sphere." At full strength: a whole is nothing over and above its parts, so explaining each part explains everything.

The reply: composition is an informal fallacy of content, not of form. A wall of small bricks need not be small, but a wall of brick is brick, and contingency behaves like the second case: if every contingent thing ceased together, nothing of the universe would remain. William Rowe stated the gap Hume leaves open: "For it is one thing for there to be an explanation of the existence of each dependent being and quite another thing for there to be an explanation of why there are dependent beings at all." Alexander Pruss's image: chickens explain eggs and eggs explain chickens, forever, and nothing yet explains why there are chickens at all.

The cost: the reply needs the totality of contingent things to be a genuine object of explanation, which Hume's view of wholes denies.

Why can't the universe just be there? (Russell)

In the same debate Copleston asked, "Then you would agree with Sartre that the universe is what he calls 'gratuitous'?" Russell answered: "I should say that the universe is just there, and that's all." At full strength the objection claims parity. Every chain of explanation stops somewhere: the theist at God, called necessary; the naturalist at the universe, called brute. Why is one stop respectable and the other not?

The two stops differ in kind. A brute fact is a contingent fact with no explanation. God, on the argument, is not a contingent fact left unexplained but a being explained by His own nature. To stop at the universe is to stop at something that could have been otherwise and call it reasonless. Pruss states the stakes: "Claiming to be a brute fact should be a last resort. It would undercut the practice of science." Inquiry presupposes that contingent things have reasons; exempt the largest one and the presupposition is lost everywhere.

The cost: the PSR cannot be proved without being assumed; its defenders treat it as a presupposition of reason, which the critic may decline at that cost.

Does it smuggle in the ontological argument? (Kant)

Immanuel Kant, in the Critique of Pure Reason (1787, B632-35), read the argument as two steps: from experience to some absolutely necessary being, then to what that being is, where, Kant argued, reason has one candidate, the most real being. But that a most real being exists necessarily is the ontological argument's claim, which Kant had rejected, so the cosmological argument falls with it. The ontological argument goes back to Anselm, whom Volume One, Resolving the Free Will Dilemma, addresses directly.

Two replies are standard. The first step already establishes a necessary being, as J. J. C. Smart observed; the second identifies it rather than proving existence from a concept. And Kant assumed that the necessity in question is logical, a being whose non-existence is inconceivable; the argument needs only factual necessity, a being that exists from itself and cannot cease.

Volume Five adds a third: the identification proceeds from what aseity entails. To exist a se is to be bounded by nothing outside oneself, and there cannot be two such beings, "for each would bound the other and neither would then be a se." That reasoning asks what an existing being must be; it never travels from a definition to existence.

What remains: oneness and self-existence are not yet goodness, knowledge and will, and further steps are required.

Does the principle of sufficient reason collapse everything into necessity? (van Inwagen)

Peter van Inwagen pressed the most rigorous objection in An Essay on Free Will (1983). Take the conjunction of every contingent truth. If the PSR holds, that conjunction has an explanation. The explanation cannot be contingent, for then it would be one of the conjuncts and would explain itself. It cannot be necessary, for whatever a necessary truth entails is necessary, and the conjunction would then be necessary too. So either the PSR is false or nothing is contingent. This is the PSR's own version of modal collapse.

Pruss's reply turns on one word. A reason can be sufficient in two senses, he argues: logically sufficient, so that it entails what it explains, or sufficient to explain it. A free choice explains its outcome without entailing it. A necessary being who freely creates explains a contingent world without making it necessary.

The same reply meets the version aimed at divine simplicity. Volume Four holds that necessity belongs to God's act taken in itself; "the creating of this world" names that act by its effect, and it is the effect that could have been otherwise. The variation sits on the created side, never in God.

The cost: the reply works only if the necessary being acts freely, and that is a claim about personhood the argument must still earn.

Could the universe, or a multiverse, be the necessary being?

Bede Rundle offered the naturalist's best candidate: matter-energy is conserved, its configurations change while the stuff persists, so matter-energy is necessary, and the necessary beings are many and internal to the universe. A multiverse version makes the ensemble of universes necessary instead.

Three replies. Could there have been more or less matter-energy than there is? If so, the total is contingent. If the material nexus is necessary, whatever follows from it is necessary too; in the Stanford Encyclopedia's words, "Everything in the universe would be necessary, which is a disquieting position." A multiverse is a larger assemblage of contingent members, and Hume's question returns one level up.

The books sharpen the point. What exists from itself is bounded by nothing outside itself, and a whole composed of parts, measurable and changing, is bounded at every frontier we can reach; Volume Six argues that conclusion from physics. The doctrine of creatio ex nihilo says the same from theology's side: the universe is neither eternal matter nor an emanation of God.

The cost: the reply rests on the contingency of the parts and their sum, which a determined naturalist may deny.

For the first axioms argued from the ground up, Volume One is free.

What does Frame-Indexed Classical Theism add to the argument?

Frame-Indexed Classical Theism (FICT) is a research program in analytic theology that resolves classical theological dilemmas by diagnosing them as artifacts of a single formal error. It enters the argument from contingency where classical theism and theistic personalism read the necessary being from opposite ends, and it adds a reading on which both are right. Its statement sits at FICT.

Classical theism, the tradition of Augustine and Aquinas, reads the conclusion from God's own frame: the necessary being is not the first member of a series but subsistent being itself, outside every series. That protects transcendence. Theistic personalism presses the obvious question: being itself, with no deliberation and no before and after, looks from where we stand like a principle, and the argument needed a Someone to choose this world.

Theistic personalism, in Richard Swinburne and Alvin Plantinga, reads it from our finite, human frame: a necessary agent who knows, deliberates and acts. That protects agency, and it is the reading Leibniz's own next step invites. Classical theism presses back: an agent who knows and acts as we do, only without limit, is the largest member of the class of explainers, and belongs among the things the argument set out to explain. Each side has seen something true.

FICT holds that terms whose content involves modality or agency, "necessary" and "person" among them, carry the mode of the being they are said of, and that predicating them univocally across the divide is the error the books call the Many Beings Fallacy. Restore the index and both readings stand, each true in its frame: in God's own frame the one God is subsistent being itself, and in ours He is the Someone who chose this world. Four results follow.

One. Aseity admits no plurality, because two self-existent beings would bound each other. The necessary being is unique, which is the step Leibniz covered in a single clause.

Not a quantity. God is the Actual Infinite, and in Volume Five's words His infinity "is not a quantity, however large." He is not the biggest link in the chain of causes but the One no addition of links could reach, which is why the chain's length never mattered.

Finite because contingent. The argument does not assume a beginning; the books find one as a consequence. Volume Three: "This contingency boundary is the primary and decisive ground for the block's finitude: because the created order exists only as sustained by God, it cannot be a self-standing, beginningless whole." The kalam's traversal reasoning corroborates the result, and physics can evidence a boundary to the measurable order without certifying the edge of being. Here the books go further than Aquinas, who held the beginning indemonstrable.

Sustained now. God grounds and sustains the finite world's reality at every moment without displacing creatures as real causes, the ground of being in the classical sense and the root of providence. "He is before all things, and in him all things hold together" (Colossians 1:17). "The Son is the radiance of God's glory and the exact representation of his being, sustaining all things by his powerful word" (Hebrews 1:3).

The case for a finite, sustained creation runs through the series, Volumes Three to Five.

Why must the necessary being be personal?

The contingency argument for God reaches a Someone because of what it explains: a world that could have been otherwise. A necessary cause that produced its effect by necessity would produce a necessary effect, and van Inwagen's dilemma would close. A world that could have been otherwise needs a cause that could have done otherwise, an understanding that holds the possibilities and a will that settles one.

Volume Four states the same conclusion from the side of aseity. The one act of creation is "uncoerced and unnecessitated," because the world adds nothing to God's perfection and answers no lack in Him; "the universe is a gift, not a consequence." Any answer to why God created begins from that gift, and Scripture's worship says it in the same terms: "You are worthy, our Lord and God, to receive glory and honor and power, for you created all things, and by your will they were created and have their being" (Revelation 4:11).

Personal in which sense? The site's answer on personhood applies here: God is not less than personal; He is personal without the composition and unrealised remainder our word carries. The argument does not reach the Trinity, which is known by revelation, and the position argued here offers no doctrine of it.

Nor does the sustaining act crowd out our freedom. The one act holds both the creaturely cause and its causing in being, and, in Volume Four's words, "sustaining a contingency as contingent is not determining its content." Our free will and our relationship with God are sustained, not replaced.

Volume One, Resolving the Free Will Dilemma, argues creaturely freedom from its first axiom.

How the positions compare

Six answers to Leibniz's question, side by side.

Frequently asked questions

What is the contingency argument for God in simple terms?

Things that could have failed to exist do not explain their own existence. Neither does any collection of them, the universe included. So there must be a being that exists from itself, by the necessity of its own nature, and that being explains why anything else exists at all. Aquinas, Leibniz and Craig each state the argument this way, with different emphases, and each calls the being God.

Who caused the necessary being?

Nothing did, and nothing needs to. The principle of sufficient reason asks for an explanation of every contingent thing, and a necessary being is not contingent: its explanation is its own nature. Asking for its cause treats it as one more member of the chain it was introduced to explain. Leibniz and Craig both insist that God is not exempt from the principle; He satisfies it in the one way open to a being that exists from itself.

Does the argument from contingency prove the God of the Bible?

It reaches one necessary, self-existent, personal Creator who sustains all things, which is the God Scripture names, but it does not reach the Trinity, the incarnation or the cross. Paul began at the Areopagus with the Maker in whom we live and move, then moved to the man God raised from the dead (Acts 17:31).

What if the universe has always existed?

The argument still applies. Aquinas built the Third Way to bind a world without beginning, and a contingent universe needs explaining whether it is billions of years old or eternal. An eternal universe would defeat the kalam, not this argument. The books go further and hold that the universe is in fact finite, precisely because it is contingent.

Is the argument from contingency the same as the cosmological argument?

It is one member of the cosmological family. The kalam reasons from a beginning; the arguments from motion and causation reason from change and causes; the contingency argument reasons from the bare fact that contingent things exist. Aquinas's Third Way and Leibniz's argument are its two classic statements.

Where to go from here

The argument from contingency was never about the first link of a chain. Aquinas would grant the chain no first link and still ask what holds it; Leibniz would ask why there is a chain at all. Its answer is a God who holds every link now, unique because self-existent, infinite without being a quantity, and free in creating a world that did not have to be. Any doctrine of God worth the name has to reckon with that answer, and the Many Beings series argues it straight through, volume by volume, rather than collecting essays that talk past each other. Volume One is where it begins, and your copy is free.