Why Does Anything Exist? The Leibnizian Contingency Argument

Of all the questions that have occupied the minds of philosophers and theologians across the centuries, none cuts deeper than the one posed by Gottfried Wilhelm Leibniz in 1697: Why is there something rather than nothing? This deceptively simple question strikes at the very foundation of existence itself. It does not ask merely how things came to be arranged as they are, nor does it concern itself solely with the temporal origins of the cosmos. It asks why there is a cosmos at all, why anything exists in the first place, and whether the existence of the world demands an explanation that transcends the world itself.

The Leibnizian Contingency Argument represents one of the most enduring and intellectually formidable cases for the existence of God in the history of Western thought. Unlike arguments that depend on the universe having a temporal beginning, this argument functions even if the universe were past eternal. Its force lies not in the question of when things began but in the question of why things exist at all. In an age of increasing philosophical skepticism, the argument from contingency has experienced a remarkable revival among analytic philosophers, receiving rigorous new formulations that would have been unavailable to Leibniz himself.¹

The Principle of Sufficient Reason

At the heart of Leibniz's argument stands one of the most consequential principles in the history of philosophy: the Principle of Sufficient Reason (PSR). Leibniz articulated this principle with characteristic precision in his Monadology (1714): "No fact can be real or existing and no statement true without a sufficient reason for its being so and not otherwise."² In other words, nothing exists without a reason, and nothing is true without an explanation.

Leibniz held that all reasoning rests upon two foundational pillars. The first is the Principle of Non-Contradiction, which governs the domain of necessary truths (truths of reason). The second is the Principle of Sufficient Reason, which governs the domain of contingent truths (truths of fact). Together, these two principles constitute the rational framework within which all genuine inquiry operates. The PSR is not merely a philosophical preference; it is the very engine of scientific investigation. Every time a scientist asks "why?" and expects an answer, every time a researcher refuses to accept that an observed phenomenon simply has no explanation, the PSR is being presupposed. To abandon it would be to undermine the rational foundations of all inquiry.

Contingent and Necessary Existence

The argument turns on a fundamental metaphysical distinction between two kinds of existence: contingent and necessary. A contingent being is one that exists but need not have existed. Its nonexistence is logically possible, and it depends on something outside itself for its existence. Every physical object, every person, every planet, and every galaxy falls into this category. The desk at which one sits could have failed to exist. The earth might never have formed. The universe itself, in its particular configuration, is not something whose existence is demanded by the laws of logic alone.

A necessary being, by contrast, is one that exists by the necessity of its own nature. Its nonexistence is impossible. It does not derive its existence from any external source; rather, it contains within itself the sufficient reason for its own existence. Leibniz identified this necessary being as God, writing in Monadology Section 38: "The final reason of things must be found in a necessary substance, in which the detail of changes exists only eminently, as in their source, and this it is which we call God."³

The Structure of the Argument

The logical architecture of the argument can be stated with elegant simplicity. In his treatise On the Ultimate Origination of Things (1697), Leibniz developed the argument in its most comprehensive form, but it can be distilled into a clear syllogistic structure. William Lane Craig has offered one of the clearest modern formulations:⁴

1. Everything that exists 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 exists.
4. Therefore, the universe has an explanation of its existence. (from 1 and 3)
5. Therefore, the explanation of the universe's existence is God. (from 2 and 4)

The crucial insight of the argument lies in its treatment of infinite regress. Even if one were to posit an infinite chain of contingent causes, with each cause explained by the one before it, the entire chain would remain contingent. The series as a whole would still lack a sufficient reason for its existence. As Leibniz observed in Monadology Section 37: "As all this detail only involves other contingents, anterior or more detailed, each one of which needs a like analysis for its explanation, we make no advance."⁵ Explaining each link in a chain does not explain the chain. Accounting for each car on a train does not account for the train itself. The sufficient reason must lie outside the series of contingent things altogether, in a being whose existence is necessary rather than contingent.

Historical Defenders and Contemporary Revival

While Leibniz gave the argument its most recognizable modern formulation, the reasoning has far deeper roots. The medieval Islamic philosopher Avicenna (Ibn Sina, 980-1037) is arguably the originator of the argument from contingency, and Thomas Aquinas developed a version of it in his Third Way (from possibility and necessity) in the thirteenth century.

In the early eighteenth century, Samuel Clarke deployed the argument in his celebrated Boyle Lectures of 1704 and 1705, published as A Demonstration of the Being and Attributes of God (1705). Clarke employed the PSR to reason from a contingent series of causes to a necessary being, and his work remained a touchstone of natural theology for generations. Clarke himself engaged in a famous correspondence with Leibniz during 1715 and 1716, producing one of the great philosophical exchanges in Western intellectual history.⁶

In the late twentieth and early twenty-first centuries, the argument has experienced a striking revival. Alexander Pruss of Georgetown University published The Principle of Sufficient Reason: A Reassessment (2006), the first English-language monograph devoted to the PSR in nearly fifty years. Pruss developed what he calls the "Big Contingent Conjunctive Fact" (BCCF) formulation: there exists a single contingent fact that encompasses all other contingent facts, and the PSR demands an explanation for it, one that must involve a necessary being.⁷ Robert C. Koons of the University of Texas has offered a rigorous mereological formulation using the tools of contemporary modal logic, demonstrating that the cosmos (understood as the aggregate of all wholly contingent facts) is itself a wholly contingent fact that demands explanation.⁸ Richard Swinburne of Oxford has developed an inductive version, arguing that the existence of a contingent universe is best explained by the existence of a necessary God as an inference to the best explanation.⁹

Major Objections and Responses

No philosophical argument of this magnitude has gone unchallenged, and the Leibnizian argument has faced formidable objections across the centuries.

The Brute Fact Objection. Perhaps the most famous challenge came during the 1948 BBC Radio debate between Fr. Frederick Copleston and Bertrand Russell. When Copleston presented the argument from contingency, Russell offered his celebrated retort: "I should say that the universe is just there, and that's all."¹⁰ For Russell, the universe is simply a brute fact requiring no further explanation. Yet this response, for all its rhetorical force, amounts to a refusal to explain rather than a genuine alternative. If brute facts are permissible at the most fundamental level of reality, then the rational foundations that undergird all scientific and philosophical inquiry are compromised. To accept the universe as a brute fact is to make an enormously strong metaphysical claim, one that demands justification at least as rigorous as anything the theist proposes.

The Fallacy of Composition. David Hume argued that even if every member of a collection has a cause, it does not follow that the collection as a whole has a cause. However, the Leibnizian argument does not commit this fallacy. It does not reason from "each part is contingent, therefore the whole is contingent." Rather, it applies the PSR directly: the fact that this particular collection of contingent things exists is itself a contingent fact, and the PSR demands an explanation for it. Moreover, some cases of compositional reasoning are perfectly valid. If every brick in a wall is red, the wall is red. If every component of the universe is contingent (that is, could fail to exist), the universe as a whole could fail to exist.

Kant's Critique. Immanuel Kant argued that the cosmological argument secretly depends on the ontological argument, since identifying the necessary being requires the concept of a most perfect being whose nonexistence is impossible. Kant further contended that "existence is not a predicate" and that the PSR is merely a regulative principle of reason rather than a constitutive feature of reality. Contemporary defenders have responded by distinguishing between strict logical necessity and broadly logical necessity. A necessary being need not be one whose existence is analytically certain; it may be a being whose nature is such that it exists in all metaphysically possible worlds. This distinction resolves Kant's objection without requiring recourse to the ontological argument.¹¹

Distinction from the Kalam Cosmological Argument

It is important to distinguish the Leibnizian argument from the better-known Kalam Cosmological Argument. The Kalam argues that everything that begins to exist has a cause, and that the universe began to exist; therefore, the universe has a cause. The Leibnizian argument makes no such temporal claim. Its central principle is the PSR, not the impossibility of actual infinites or the finitude of the past. As Craig himself has noted: "The Leibnizian cosmological argument is not seeking a temporally first cause; it is consistent with the universe's being past eternal, and one may still ask of an eternal universe, 'Why is there something rather than nothing?'"¹²

The two arguments are best understood as complementary rather than competing. The Kalam establishes that the universe had a temporal beginning and therefore a cause; the Leibnizian argument establishes that a necessary being must exist to ground the existence of any contingent reality whatsoever. Together, they form a powerful cumulative case for the existence of a transcendent, necessary, personal Creator.

The Scriptural Witness

While the Leibnizian argument is a work of natural theology (reasoning from general features of the world rather than from special revelation), its conclusions resonate deeply with the testimony of Scripture. The Apostle Paul declared that "since the creation of the world God's invisible qualities, his eternal power and divine nature, have been clearly seen, being understood from what has been made" (Romans 1:20, ESV). The contingency of the created order reveals the necessity of the Creator. Paul made a similar appeal at the Areopagus, proclaiming that the God "who made the world and everything in it" is the one in whom "we live and move and have our being" (Acts 17:24, 28, ESV). This language of ontological dependence, of all things having their being in God, echoes the very metaphysical structure that the contingency argument identifies.

The Apostle Paul further wrote of Christ that "he is before all things, and in him all things hold together" (Colossians 1:17, ESV). Here the sustaining ground of contingent reality is identified not merely as an abstract necessary being but as the personal God who upholds all things by the word of his power. The elders in Revelation worship God with the declaration: "You created all things, and by your will they were created and have their being" (Revelation 4:11). All things exist by God's will; they are contingent upon his creative act. And in perhaps the most profound self-disclosure in all of Scripture, God identifies himself to Moses simply as "I AM WHO I AM" (Exodus 3:14). The classical theistic tradition, from Aquinas onward, has understood this as a declaration of God's necessary, self-existent nature: he does not receive existence from another; he is existence itself (ipsum esse subsistens).¹³

Conclusion: The Question That Will Not Go Away

Leibniz's question persists because it cannot be dissolved by scientific progress. No discovery about the mechanism of the universe's development can answer why there is a universe to develop in the first place. Cosmology may trace the expansion of space and time back to a singularity, but the question of why that singularity (or any reality at all) exists rather than nothing remains untouched by empirical investigation. The Leibnizian Contingency Argument presses this question with relentless logical force: if contingent things exist, and if the Principle of Sufficient Reason holds, then a necessary being must exist as the ultimate ground of all reality. The history of philosophy has produced no compelling reason to deny either premise. The universe, in all its vastness and complexity, points beyond itself to one who exists not by the permission of another, but by the necessity of his own eternal nature.

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Footnotes

¹ See especially Alexander Pruss, The Principle of Sufficient Reason: A Reassessment (Cambridge: Cambridge University Press, 2006); Robert C. Koons, "A New Look at the Cosmological Argument," American Philosophical Quarterly 34 (1997): 193-211; Alexander Pruss and Joshua Rasmussen, Necessary Existence (Oxford: Oxford University Press, 2018).

² Gottfried Wilhelm Leibniz, Monadology, Section 32 (1714).

³ Leibniz, Monadology, Section 38.

⁴ William Lane Craig, Reasonable Faith: Christian Truth and Apologetics, 3rd ed. (Wheaton, IL: Crossway, 2008), 106.

⁵ Leibniz, Monadology, Section 37.

⁶ The Leibniz-Clarke correspondence (1715-1716) remains one of the most significant exchanges in the history of natural theology. See H.G. Alexander, ed., The Leibniz-Clarke Correspondence (Manchester: Manchester University Press, 1956).

⁷ Pruss, The Principle of Sufficient Reason, chapters 4-6.

⁸ Robert C. Koons, "A New Look at the Cosmological Argument," American Philosophical Quarterly 34 (1997): 193-211.

⁹ Richard Swinburne, The Existence of God, 2nd ed. (Oxford: Oxford University Press, 2004), chapters 4-7.

¹⁰ "A Debate on the Existence of God," BBC Radio, January 28, 1948. Transcript in John Hick, ed., The Existence of God (New York: Macmillan, 1964).

¹¹ Craig, Reasonable Faith, 101-106. See also Alvin Plantinga, The Nature of Necessity (Oxford: Clarendon Press, 1974) for the distinction between strict and broadly logical necessity.

¹² William Lane Craig, "Confusing the Leibnizian and Kalam Cosmological Arguments," Biola University Blog, 2017.

¹³ Thomas Aquinas, Summa Theologiae, I, q. 3, a. 4. See also Edward Feser, Aquinas: A Beginner's Guide (London: Oneworld, 2009), 91-100.

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Dr. Peter J. Carter is the founder and CEO of Theology in Focus, a nonprofit ministry dedicated to restoring theological literacy to the body of Christ. For more articles on apologetics, systematic theology, and church history, visit theologyinfocus.org/blog.

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