The Argument from Contingency

A tree might never have grown, a mountain might never have formed, a person might never have been born. These things are real, but they did not have to exist. That is why we call them contingent beings. Here, the word “being” simply means a reality that exists.

Calling a person contingent therefore does not reduce their value in any way. Nor does it mean that they are fragile at every moment. The question concerns their existence: why are they here, when they could have failed to be here? A huge star raises this question just as much as a tree does.

A cause is something on which the coming into being or existence of a thing depends. Parents, for example, bring their child into existence. But knowing an immediate cause does not necessarily answer the whole question. The parents themselves exist thanks to other realities, whose existence also needs an explanation.

At the other end of the argument stands the necessary being. This means a reality whose non-existence is impossible. Here, “necessary” therefore does not mean “very useful”, as when we speak of a necessary tool. It means that this reality cannot fail to exist.

A further distinction will matter in Thomas Aquinas’s argument. A being is necessary in itself if it does not receive from another reality what explains its necessary existence. We must distinguish this independence from the mere impossibility of not existing. The argument ultimately seeks a being that is necessary in itself.

Mathematics offers a limited comparison. The result 2 + 2 = 4 does not become true because an event makes it true. Its opposite is impossible, but the argument seeks more than a mathematical truth. A number, on its own, does not make either a tree or a person exist.

We call a reality abstract if it does not itself produce effects. A number is one example. In this debate, a concrete reality can act or be acted upon. The necessary being we are seeking must be concrete: it must explain the existence of real things, rather than merely provide an idea.

This distinction already answers a common question: if God explains the world, what explains God? The argument does not say that everything must receive its existence from something else. It says that whatever could have failed to exist needs an explanation. A being that is necessary in itself is precisely what does not belong to this category.^[1]

This line of thought does not come from just one Christian thinker. Aristotle, a Greek philosopher, already distinguishes what can exist from what actually exists. Avicenna, a Persian philosopher, clarifies the difference between a being that is necessary in itself and a possible being. Moses Maimonides takes up this distinction in Jewish thought. Thomas Aquinas inherits these ideas and develops them.^[2]

More recently, Saul Kripke clarified the language of possible worlds. A possible world is a way reality could be without contradiction. A contradiction brings together claims that rule each other out, such as the idea of a square circle. A necessary thing exists in every truly possible situation; a contingent thing can be absent from some of them.^[3]

Saint Thomas Aquinas is a Christian thinker whom the Church recognises as a major authority in explaining the faith. In his Summa Theologica, he presents five paths of reasoning towards God. He calls the third the way of possibility and necessity. He begins with beings that come into existence and then pass away.

He introduces his approach as follows:

“The third way is taken from possibility and necessity.”^[4]

Thomas first seeks to establish that a necessary reality exists. He then distinguishes two cases: this reality receives its necessity from another, or it is necessary in itself. The first case shifts the explanation to something else again. The second reaches a reality that does not receive its necessity.

Why does this distinction matter? Because a necessity that is received always points us back to whatever gives it. Thomas argues that a series of necessities received in this way does not provide its own foundation, even if it has no first member in the past. He therefore seeks a reality that is necessary in itself, able to explain the others without depending on them.

To understand the dependence this argument concerns, let us distinguish an origin in the past from support in the present. Some things depend on an event that happened long ago. Others depend on an activity or a support that must be present now. These two forms of dependence do not raise exactly the same question.

A grandfather can die while his grandson continues to live. His past existence played a role in the birth of his descendants. But he does not need to stay alive for them to continue existing. Here, the succession of generations explains an origin in the past.

A melody played by a musician offers another image. It depends on the musician’s activity while it is being played. A hanging chandelier likewise depends on the support holding it up. These examples show present dependence: the thing depends on something else now, rather than only when it first came into being.^[5]

At a deeper level, Thomas seeks what explains the present existence of realities that cannot exist on their own. His question therefore goes beyond the search for the first event. Here, the word foundation means what enables other realities to exist without itself depending on them. It does not mean an object hidden underneath the world.

These comparisons make the question easier to grasp, without turning God into a ceiling or a musician. They clarify one specific point: explaining how something began is not always enough to explain its present dependence. The argument seeks a foundation for existence, rather than just an earlier event.

The Kalam cosmological argument concerns the beginning of the universe. Here, the universe means the whole material world. The argument from contingency asks a different question: even a universe that had always existed could depend on something else. Having no beginning in time would still not explain that existence.

Leibniz is the philosopher shown in the image at the start of this article. He takes up the search for an ultimate explanation, expressing it in a way that has become famous. In the Principles of Nature and Grace, in 1714, he asks:

“why is there something rather than nothing?”^[6]

This question is not just about the birth of stars or living beings. It concerns everything that exists without being necessary. Nothingness means the total absence of reality. It is not an empty space waiting to be filled: a space would already be something.

For Leibniz, we cannot answer simply by pointing to one more thing of the same kind. Explaining a tree through a seed remains useful and true. But the seed, the soil and everything that enables them to exist also need an explanation. The search is therefore not yet over.

Leibniz formulates the principle of sufficient reason. This principle states that there is an explanation for what is real. It asks why things are this way rather than another way. A reason is “sufficient” when it truly answers this question, rather than repeating that the thing exists.^[7]

Here, the word “reason” does not necessarily mean a human intention. A tree’s growth can be explained without the tree having decided to grow. Nor does the principle claim that we already know every explanation. A reason can exist while remaining unknown to us.

This difference matters a great deal. Not knowing the explanation for a result does not prove that it has none. A researcher keeps working precisely because they expect an explanation. They distinguish a question that remains open from a complete absence of a reason. Leibniz extends this confidence to questions about existence itself.

Its defenders therefore see this principle as a deep requirement of thought. Scientific research seeks to understand why things happen as they do. Historical investigation asks why an event took place. Why should this search stop when faced with the whole collection of realities that could have failed to exist?

Leibniz also distinguishes truths whose opposite is impossible from facts that could have been different. A mathematical result belongs to the first group; the existence of this tree belongs to the second. Understanding how the tree grows provides particular explanations. It does not yet tell us why the whole collection of things exists.^[8]

The ultimate explanation therefore cannot be another thing that could have failed to exist. If it could be absent like the tree, it would only add a new question. A being that is necessary in itself answers this difficulty: it explains without itself needing an outside explanation. It does not create itself; it does not need to be created.

One possible answer is that each thing is explained by another, then another, without ever stopping. This series would be infinite. That means that, as we traced the explanations back, we would never reach a final member. No particular explanation would therefore be missing. Why ask for more?

Leibniz answers with a comparison involving books. Imagine that each book was copied from an earlier book. The copying explains why this copy has this content. Now suppose that the series has no beginning: every book would always have a model from which it was copied.

We would then know how the content passes from one copy to another. But why does this collection of books exist, with this content? The absence of a first copy does not answer this new question. It only prevents us from finding a first book in the series.^[9]

The central idea is therefore simple: multiplying dependencies does not, on its own, produce independence. However, we need to state clearly what still needs explaining. Defenders of the argument consider all contingent facts together. They ask why these facts are true rather than others.

A modern formulation can thus be presented in six steps:

1. Some realities exist even though they could have failed to exist.
2. Their existence needs a sufficient explanation.
3. The fact that all these realities exist in this way is itself contingent.
4. A contingent reality included in this collection cannot provide its complete explanation.
5. This explanation must therefore come from a necessary reality.
6. The philosophical tradition recognises in this foundation what it calls God.

The third point needs to be defended, and we will return to it. Saying that the elements have a property is not enough to give that property automatically to the whole. We need to show why the overall fact could itself be different. This is one of the important debates surrounding the argument.

The fourth point also deserves particular attention. If a contingent reality explains the whole collection, its existence is already part of what needs explaining. The thing chosen to explain everything would therefore still need an explanation. On its own, it would not provide the complete answer being sought.^[10]

The philosopher Alexander Pruss develops this approach by bringing all contingent facts together in a single question. Why are all these facts true? He also examines a less demanding starting point: these facts could have an explanation. In this other formulation, he therefore does not begin by claiming that each one actually has an explanation.

With additional rules about what is possible or necessary, he again seeks to establish the existence of a necessary being. This version is a different argument, with its own framework. The statement “an explanation is possible” is not enough, on its own, to provide the whole proof.^[11]

Other philosophers present and defend this approach today: Edward Feser, Joshua Rasmussen, Frédéric Guillaud and Matthieu Lavagna. Their presentations differ, but their central question remains. The aim is to explain why these things exist, without leaving each answer endlessly dependent on a new thing that needs explaining.^[12]

An important objection proposes that the universe itself is the necessary reality being sought. Its elements could change, while its non-existence would be impossible. The same whole could therefore exist necessarily while having different states. Observing changes is not enough, on its own, to refute this proposal.

We need to distinguish two questions. Could our material universe have failed to exist at all? And why are the facts that could have been different nevertheless this way? The first concerns the world’s existence; the second also concerns its contents and organisation.

Defenders of the argument maintain that we can conceive of the absence of our material universe without contradiction. They also consider a universe with different features. However, conceiving of a situation without an apparent contradiction is not the same as proving that it is truly possible. This line of thought therefore needs discussion, rather than simply pointing to change.^[13]

The world we observe contains certain things, arranged in a certain way. It follows physical laws. These are the rules through which physics describes how matter behaves. These laws involve fixed values. These are the physical constants.

Why these laws and these values rather than others? We can conceive of a universe with different constants or without galaxies, with no apparent contradiction. This invites us to seek an explanation for these features. But their possible variation does not, on its own, prove that any material whole could be absent.

The current scientific model also offers an estimate of the universe’s age. A model is a representation that connects observations through assumptions and calculations. Such an estimate therefore depends on measurements interpreted within this framework. It is not an essential starting point for the argument.

Even a universe without a beginning would still raise questions about its existence and its features. The argument therefore does not depend on any particular age of the world. It asks whether the world could have failed to exist. It also seeks to explain why all the contingent facts about it are true.

The fine-tuning of the universe raises a related question. This expression means the precision of the physical values that allow complex structures and life. Why do these values have the form they do? For defenders of the argument, this precision strengthens the search for an explanation without making the universe necessary.

We can then broaden the proposal and imagine a multiverse. This word means a collection of several universes. Our universe would be just one member of this larger collection. But, if this collection exists, why does it exist with this organisation rather than another?

The physicist and philosopher Bernard Carr highlights a difficulty with this hypothesis. A mechanism capable of producing different universes would itself have to follow certain rules. These rules would have to allow universes in which life is possible to arise. Their existence and their features would therefore still need an explanation.^[14]

Let us return to the objection about the elements and the whole. It rightly reminds us that a property of the parts does not automatically belong to the whole. The answer therefore does not consist in repeating that each thing is contingent. It examines the overall fact made up of all contingent facts together.

Here, a fact means something that is true of reality. The existence of this person, for example, is a contingent fact. If they had never been born, the fact that all the people currently present exist would no longer be true. This overall fact can therefore fail to hold, even if other people still exist.

The same point applies to all contingent facts taken together. If one of them were different, that exact combination would no longer be true. This combination therefore needs an explanation according to the principle of sufficient reason. This does not assume that all realities must be able to disappear at the same time.^[15]

Thus, proposing a necessary universe is not enough to explain why all these contingent facts are true. Even under this hypothesis, the question remains. The argument seeks what explains their existence without itself being another contingent reality among them. In this sense, it works back towards a necessary foundation.

The argument first reaches a reality that is necessary in itself. But why call it God? A complete answer requires further analysis. We need to ask what such a reality must be like to truly explain the world. This second investigation concerns its characteristics.

First, it cannot simply be one more contingent reality. We say that it is transcendent. This means that it is not part of the world in the way a star or a planet is. This distinction therefore does not mean a great distance in space.

Next, this reality must not depend on parts being put together. Otherwise, why would these parts be joined in this way? Their union would need a new explanation. Here, we speak of simplicity. This word means the absence of assembled parts, rather than poverty or a lack of richness.

Classical analysis also holds that it has no arbitrary limits. An arbitrary limit would be a particular limit left without a sufficient reason. Why this limit rather than another? If its explanation still depended on another reality, we would not have reached the independent foundation being sought.

It is within this framework that classical analysis defends the immateriality of this foundation. This means that it is not made of matter. The matter we observe has limits and particular features, whose explanation is precisely what we are seeking. The ultimate foundation cannot simply have these same limits without answering the question they raise.^[16]

This reality must also be able to bring concrete realities into existence. A mathematical formula is not enough: describing a phenomenon does not, by itself, produce it. The foundation being sought therefore has real power. It explains the world’s existence, rather than being merely a way of representing it.

Classical analysis also reaches a reality capable of knowing and willing. This personal character plays a role in its answer to a difficulty: how can a necessary being produce a contingent world? The answer appeals to freedom. God can create this world without being obliged to create it.

This answer distinguishes God’s necessary existence from his act of creation. It does not present the world as a consequence that would necessarily follow from him. We will return to this difficulty among the objections. Explaining why this foundation knows and wills requires further reasoning.

Finally, classical analysis maintains that there is only one being that is necessary in itself. If two beings of this kind differed, one would have something that the other lacked. This difference would need explaining. An arbitrary limit in one of them would bring back the question that the necessary foundation was meant to resolve.

These developments give the conclusion a precise meaning, but each needs its own argument. The point is not simply to add an unknown force to the universe. It is a reality independent of the world, capable of explaining its existence. It does not itself receive its existence from any other.

Spinoza, another philosopher who reflected on God and nature, identifies the two. The classical answer rejects this identification: the nature we observe contains the contingent realities and facts whose explanation we are seeking. Calling them God does not resolve this dependence. The foundation therefore explains nature while being distinct from it.^[17]

This conclusion does not yet prove the whole of Christianity. It does not directly reveal the Trinity. This name means the one God in three persons. Nor does it prove the Incarnation. This word means that God became man in Jesus Christ.^[18]

The criticisms do not all concern the same point. Some challenge our way of knowing causes; others refuse to ask for an explanation of the whole universe. Still others think that the conclusion cannot be the Christian God. Distinguishing these questions helps us understand what each answer contributes.

David Hume: do we really see the connections between causes and their effects? This philosopher points out that we observe events regularly following one another. We then become used to expecting the second after the first. But is this habit enough to know that there is a necessary connection between them?^[19]

The classical answer distinguishes succession from dependence. The argument does not rest only on the habit of seeing one event after another. It asks why a reality that does not explain its own existence nevertheless exists. The example of the melody clarifies this difference: it depends, in the present, on the musician playing it.

Defenders of the argument add that a general rejection of real connections between causes and effects would affect many other lines of reasoning. It would also make experimental research and everyday explanations difficult. The criticism must therefore explain why it would rule out this search for a foundation while still allowing other investigations.

Immanuel Kant: can our reason go this far? Reason is our ability to think, compare and draw conclusions. Kant challenges the idea that it can establish a necessary reality beyond what we can observe. He also thinks that this approach depends on another argument.^[20]

This other line of reasoning is the ontological argument. It seeks to establish God’s existence by reflecting on what a necessary being is. Kant thinks that the argument drawn from the world ultimately relies on this approach. He therefore challenges the argument’s ability to reach its conclusion.

The classical answer maintains that the steps of its argument work back from an existing fact to its real explanation. They do not try to derive existence from a mere definition. The starting point in the world therefore matters, but the path followed to the necessary foundation must also be justified.^[21]

The answer also questions the limit Kant imposes: what reason justifies ruling out this search for a foundation? A theory that sets the limits of our knowledge in this way itself takes a position on our relationship to reality. It must therefore explain why it can establish this limit while rejecting the classical investigation.

This discussion concerns metaphysics. This word means reflection on what it means to exist and on what realities depend upon. Defenders of the argument maintain that this reflection is possible. In their view, we can ask why things exist, rather than merely describe what we observe.

Bertrand Russell: why could the universe not simply be there? In his radio debate with Father Frederick Copleston in 1948, Russell gives this answer:

“I should say that the universe is just there, and that's all.”^[22]

The universe would then be a brute fact. This expression means a real fact without an ultimate explanation. We could explain events within the world without thinking that the whole world has an explanation. The objection therefore does not reject every particular investigation: it refuses to extend their demand for explanation to the whole.

Defenders of the argument ask what justifies stopping here. Why should reality as a whole be exempt from explanation? Saying that it is simply there states that it exists, but does not answer the question being asked. Their answer therefore maintains the principle of sufficient reason even in this investigation.

Pruss also points out a wider difficulty. If some contingent facts can exist without any reason, why could our own perceptions not do the same? In his view, this possibility weakens our trust in explanations. The discussion thus concerns the consistency of our search for truth, beyond the question of religion alone.^[23]

Peter van Inwagen: would a necessary God make the world necessary? The objection asks whether a necessary being necessarily produces its effect. If the world followed from God in this way, it could not fail to exist. The conclusion would then seem to contradict the starting point: a contingent world.^[24]

The classical answer distinguishes God’s necessary existence from his free act of creation. The world does not follow from him as a conclusion necessarily follows from its starting points. God can give existence without being obliged to produce this particular world. His necessary existence therefore does not make everything he does necessary.

The freedom invoked here does not mean only that no outside pressure acts on God. It means that his creative act does not produce this world through an unavoidable necessity. It is precisely this free character of the connection between God and the world that answers the objection. The distinction concerns the act as much as the existence of the one performing it.^[25]

Finally, the argument does not prove the whole Christian faith. This observation is correct about its scope, but it does not refute its conclusion. A foundation is not a whole house; it nevertheless serves an essential purpose. The argument answers the question of the world’s dependence, and other investigations can then move forward.

The Church affirms that the human mind can truly know God’s existence from the created world. It therefore does not present faith as an escape from questions. It recognises a real capacity in our reason. The argument from contingency belongs to these paths of reflection.

In 1870, the First Vatican Council expresses this teaching. A council is a gathering of bishops that exercises the Church’s teaching authority. Here is what the text Dei Filius declares:

“Holy Mother Church holds and teaches that God, the source and end of all things, can be known with certainty by the natural light of human reason from created things.”^[26]

Here, the “natural light of reason” means what our minds can know by reflecting on the world. The text affirms this capacity without first assuming knowledge of the Bible. This teaching is dogmatic. The Church defines it as a truth belonging to the faith.

However, the council does not declare that a single philosophical formulation is compulsory. It affirms the capacity to know God. The argument from contingency is one of the paths that correspond to this teaching. It can therefore be studied with its own steps and answers.

The Catechism of the Catholic Church presents the teaching of the faith in an organised way. It explicitly mentions this path:

“The world: starting from movement, becoming, contingency, and the world's order and beauty, one can come to a knowledge of God as the origin and the end of the universe.”^[27]

Here, “becoming” means the changes things undergo. The Catechism brings together several paths of reasoning that converge and allow us to reach real certainties. It does not confuse them with a mathematical calculation. The world’s existence, its changes, its order and its beauty all contribute to this search.

The Second Vatican Council also reaffirms the teaching about knowing God. Saint John Paul II defends this capacity of reason in Fides et Ratio. The Catholic faith thus recognises a mind capable of seeking beyond the mere description of phenomena.^[28][29]

The search can then continue. The moral argument asks what truly grounds goodness. The resurrection of Jesus opens the investigation into Christianity in history. These approaches answer different questions, but they can come together in a shared search for truth.

Studying the reasons to believe in Catholicism then examines the Church and its authority. The argument from contingency prepares this path without claiming to complete all its steps on its own. It provides a foundation for a wider investigation.

This reflection also changes how we look at an ordinary life. Our bodies, our histories and the people we love do not have to exist in their own right. The Catholic answer recognises their existence as a gift. The argument began with a general question; it thus reaches something very personal.

In his Pensées, Blaise Pascal expresses his amazement at finding himself here, now, rather than somewhere else or in another age. Our existence could have been different. This thought can make us feel dizzy. The argument from contingency shows how to seek a foundation for this existence that could have failed to be.^[30]

Saint Augustine expresses how our lives are directed towards God:

“You have made us for yourself, Lord, and our heart is restless until it rests in you.”^[31]

These words do not replace the argument, but they show its spiritual significance. The world depends on a being who gives existence without receiving it. Our existence is therefore not abandoned to emptiness. The realities around us lead us to recognise the One on whom they depend.

Nor is creation an obligation imposed on God. The Catholic answer affirms that he creates freely, out of goodness. He does not seek to fill a lack in himself. The world is therefore not an inevitable extension of God: it exists because God gives.

The argument thus leads us to look differently at what seemed ordinary at the start: this tree exists, this person exists, we exist. Its conclusion is that these realities depend on a being who does not receive his existence. The Catholic answer recognises a gift here. What exists without having to exist points to the One who gives existence.

• A contingent reality exists but could have failed to exist.
• A necessary reality cannot fail to exist.
• The argument seeks a reality that is necessary in itself and depends on no other for its existence.
• Its question remains even if we suppose that the universe has no beginning.
• Explaining each element still leaves us to examine the fact that all these contingent facts are true.
• This approach leads towards God without proving the whole Christian faith on its own.
• The Church teaches that our reason can truly know God from created things.

The argument from contingency invites us to follow a question all the way through. We explain things through other things, but these still raise the question of why they exist. The conclusion is a foundation that does not receive its existence from another reality. This foundation, necessary in itself, is what we call God.

The Catholic answer holds together this demand of reason and the Creator’s freedom. The world does not exist because God needs it. It exists as a gift. What could have failed to be thus rests, at every moment, on the One who is.