The Contingency Argument: Why Does Anything Exist At All?

The Deepest Question

Gottfried Leibniz once asked what might be the most profound question in all of philosophy: Why is there something rather than nothing?

Think about it. Every object you see — your phone, the chair you’re sitting in, the planet beneath you — didn’t have to exist. The universe could have been empty. There could have been nothing at all. So why is there… anything?

This isn’t just idle curiosity. It’s the engine behind one of the most powerful arguments for God’s existence: the contingency argument.

Contingent vs. Necessary

Here’s the key distinction. A contingent thing is something that could have not existed. You are contingent — your parents might never have met. The Earth is contingent — it formed from a cloud of gas and dust that could have dispersed differently. Even the universe itself appears contingent — the Big Bang didn’t have to happen.

A necessary thing, by contrast, is something that must exist — something that exists by its own nature and couldn’t fail to exist. Many philosophers consider mathematical truths necessary in this sense. The number 7 doesn’t depend on anything for its existence.

The argument runs like this:

1. Everything that exists has an explanation of its existence — either in an external cause or in the necessity of its own nature.
2. The universe exists.
3. Therefore, the universe has an explanation of its existence.
4. The universe is contingent (it doesn’t have to exist).
5. Therefore, the explanation must be found in something outside the universe — something that exists necessarily.

That necessary being is what philosophers identify as God.

The Principle of Sufficient Reason

The argument’s backbone is the Principle of Sufficient Reason (PSR): for every fact, there must be a sufficient reason why it is so and not otherwise. Leibniz considered this self-evident. If something exists without any explanation whatsoever, we’ve essentially abandoned rationality.

Alexander Pruss, in his rigorous 2006 work The Principle of Sufficient Reason: A Reassessment, argues that denying the PSR has devastating consequences for science and everyday reasoning. If things can just pop into existence without explanation, why trust any causal reasoning? The very enterprise of science depends on the world being intelligible — on there being reasons for things.

Robert Koons reinforces this point, arguing that the contingency argument doesn’t require an absolutely universal PSR. Even a modest version — that contingent things typically have explanations — makes it overwhelmingly likely that the universe as a whole does too.

Common Objections

“Why can’t the universe just be a brute fact?” You can say that, but it comes at a steep intellectual cost. If the entire universe can exist for no reason, you’ve undermined the foundation of all explanation. As Pruss notes, once you allow brute facts, you can’t non-arbitrarily limit where they show up. Why not brute facts everywhere?

“What explains God, then?” This actually misunderstands the argument. God isn’t proposed as another contingent thing requiring an external cause. God is the necessary being — the being whose nature is to exist. Asking “who made God?” is like asking “what’s north of the North Pole?” It misapplies the category.

“Maybe the universe is necessary.” Richard Swinburne has argued persuasively against this. The universe’s properties — its particular physical constants, initial conditions, even its existence — all appear deeply contingent. Physics tells us the constants could have been different. A necessary universe would have to exist in every possible scenario, with exactly these properties. That’s an extraordinary claim with no evidence.

Why This Matters

The contingency argument doesn’t just point to a god. It points to a being with some remarkable attributes: necessary existence, immateriality (since it explains all of physical reality), and enormous power. As Leibniz himself recognized, this maps remarkably well onto the God of classical theism.

What makes this argument especially compelling is that it doesn’t depend on any gap in scientific knowledge. It’s not a “God of the gaps” argument. Even if we had a complete physical theory explaining every event in the universe, we’d still need to explain why that entire system — with those particular laws — exists at all.

Science explains things within the universe. The contingency argument asks about the universe itself. And that question, far from being outdated, is one that modern physics has only made more pressing.

The universe didn’t have to be here. But it is. Why?