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16 Reasons Why I Believe In God: (2) The Contingency of the Universe


Ruins of Pompeii    with Mt. Vesuvius in the background (c. 1900) - Wikimedia Commons (Public Domain)

Ruins of Pompeii with Mt. Vesuvius in the background (c. 1900) - Wikimedia Commons (Public Domain)

An Explanation for Everything

Science looks for explanations. But can it find the ultimate explanation? Can science explain why the universe exists — why there is something rather than nothing? Some physicists think it can; Stephen Hawking and Lawrence Krauss are two examples. They've even attempted (unsuccessfully) to show what that explanation is. What these physicists don't realize, however, (and may not like, considering they are atheists) is that they are unwittingly presupposing an idea that points to God's existence.

The belief, "there is an explanation for everything," appears to be a common scientific assumption. In philosophy, this belief is known as the principle of sufficient reason, attributed to the philosopher Gottfried Leibniz. Leibniz used this principle to formulate an argument for God's existence from the contingency of the universe. Before I explain the argument, we need to first talk about what contingency is.

Contingent being

Have you ever thought about the fact that things could've been different? For instance, your parents may not have met and you could have never been born, or Mount Vesuvius might not have erupted and Pompeii may have been spared, or......the Big Bang could never have happened. Such thoughts reveal that everything in the physical universe is contingent — that means it could have been different than it is (i.e. there's nothing that makes the current state of things necessary), and everything depends on something else for its existence. For example, your existence depends on your parents, Vesuvius' forming depended on a number of geologic events under Earth's crust, the Big Bang depended on.....? get the idea. Thus, by reflecting on these possibilities, we are able to see that the universe itself is contingent.

Necessary Being

Back to Leibniz. He reasoned that since everything in the universe is contingent, and there is an explanation for everything, then to explain why the universe exists one has to appeal to an explanation outside of the universe. In his famous book The Monadology, he concludes:

It must be the case that the sufficient or ultimate reason [for why the universe exists] is outside the sequence or series of this multiplicity of contingencies, however infinite it may be. And that is why the ultimate reason of things must be in a necessary substance... This is what we call God.[1]

For Leibniz, it doesn't matter if the universe had a beginning or is eternal, it's still contingent, and therefore requires an explanation outside of itself. Here's a version of Leibniz' argument that I find intriguing:

  1. Everything that exists has an explanation of its existence, either in the necessity of its own nature or in an outside source.

  2. If a thing is contingent, then its explanation must be in an outside source.

  3. The universe exists.

  4. Therefore, the universe has an explanation of its existence.

  5. The universe is contingent.

  6. Therefore, the explanation of the universe is in an outside source.

If the principle of sufficient reason is true (as many scientists believe), and the universe is, in fact, contingent, then it follows that the universe has an explanation grounded in a source which is both necessary (i.e. does not depend on anything else for its existence) and outside the universe (i.e. transcendent). Necessity and transcendence are attributes of God. Thus, the contingency of the universe offers a good reason to believe in God's existence.

Common Objections:

1. The principle of sufficient reason (PSR) is false. Could be. The PSR sure is difficult to deny though, for a couple of reasons: (1) it appears to be an assumption of scientific reasoning. So, if you're someone who puts a lot of stock in science, then by denying the PSR you're undercutting much of what you already believe; (2) for this objection to work, you need to explain why the PSR is false; which is ironic, since you're denying that everything has an explanation.

2. If everything has an explanation, then what's God's? Notice premise 1 says that everything that exists has an explanation, "either in the necessity of its own nature or in an outside source." Since God by definition doesn't depend on anything else for his existence, he is not contingent. God is a self-existent being — existence is part of his very essence or nature. Thus, the explanation for God's existence is in the necessity of his own nature, not in an outside source. Perhaps this helps to explain why in the biblical narrative God identifies himself to Moses simply as, "I AM" (e.g. Exodus 3:14). God (if he exists) just is. There's no further explanation.

3. There's no possible way we could know the explanation for everything. I totally agree! Good thing the argument doesn't say that. It merely says there is an explanation for everything that exists. It makes no claim about how much we can know.

4. If God is a necessary thing, and he created the universe, then doesn't that make the universe necessary as well? No, it doesn't. If God is a personal agent (i.e. can make choices), then it's possible that he could have chosen not to create the world. Hence, the universe is still contingent.

5. Why think the universe (or multiverse) is contingent? Maybe it's necessary. There are better reasons to believe the universe is contingent than necessary: (1) when we reflect on everything we experience, we are intuitively aware of the possibility that those things could've been different; (2) everything in our experience is dependent upon something else for its existence (see above); (3) as explained in my previous post, we have excellent reasons for thinking the universe had a beginning and therefore a cause, which gives us further confidence that the universe is contingent. In light of all this, why shouldn't we think the universe is contingent?

6. What if the "outside source" that explains the universe is simply the laws of nature? That doesn't work because the laws of nature are contingent as well. In fact, the laws of nature provide an additional reason to believe in God — I'll explain more in my next post.

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NOTE: If you're brave (and nerdy) enough, check out the Necessary Being website and take their interactive survey. It uses your responses and advanced logic to supposedly prove a necessary being exists. Cool!

Further Reading:

*To better understand the goals and limits of this blog series, please read the Introduction, if you haven't already. Thanks!



1. Quoted in Roger Ariew and Eric Watkins, Modern Philosophy: An Anthology of Primary Sources (Indianapolis: Hackett Publishing, 1998), p. 238.