For example, philosopher Quentin Smith writes, “The most reasonable belief is that we came from nothing, by nothing, and for nothing.” In a 2012 debate with Cardinal George Pell , atheist Richard Dawkins asserted:

A variant of this principle that some atheists also challenge is whatever begins to exist must have a cause.

In “ Testing the Causal Chain ” I responded to critics who deny the causal principle that whatever is composed of essence and existence—that is, for which existence is not part of essence—needs a cause.

Of course it’s counterintuitive that you can get something from nothing! Of course common sense doesn’t allow you get something from nothing! That’s why it’s interesting. It’s got to be interesting in order to give rise to the universe at all!

That atheists deny this form of the causal principle is significant because it plays a prominent role in several theistic arguments. For example, St. Thomas Aquinas argues in the Summa that if all beings were corruptible (what he calls “possible beings”), “then at one time there could have been nothing in existence” (I:3:2). He argues that “if this were true, even now there would be nothing in existence, because that which does not exist only begins to exist by something already existing.” The Kalam cosmological argument is another example, arguing that if the universe had a beginning it would need a cause outside itself to bring it into existence.

So what reasons do Smith, Dawkins, and other atheists give to doubt the principle that whatever begins to exist needs a cause? There are several, but let’s think through one of the more popular ones.

Modern philosophers often appeal to David Hume’s imagination argument. Hume argued that since we can imagine something coming into existence without a cause, then we have good reason to doubt that whatever begins to exist must have a cause.

For example, you might imagine the surface of a table with nothing on it, then imagine a billiard ball suddenly just appearing on it. Hume says that since you can imagine something beginning to exist without imagining a cause, and such imaginings are without contradiction, then it must be at least possible that no cause is needed to bring something into existence; thus the causal principle, according to Hume, is not certain.

There are two reasons why this argument fails.

First, his objection rests entirely on the false notion that our imagination serves as an accurate yardstick for determining what is possible in the real world. Consider again Hume’s basic argument: if we can imagine the billiard ball popping into existence on the table without imagining its cause, then it’s possible for the billiard ball to appear on the table without a cause. In other words, for Hume, whatever is separable in the imagination can be separated in reality.

But a little more thought shows that this is simply not true.

Consider the following examples. I can imagine water without at the same time imagining the molecules that make up the water. But does that mean it’s possible for water to exist without water molecules? According to Hume’s principle, we would have to answer yes. But we know in reality that can’t be.

To use an example from philosopher Scott Sullivan, I can imagine a jar of jellybeans without imagining the specific number of jellybeans. I can also imagine the jar of jellybeans without imagining whether the number is even or odd. Does that mean the jar of jellybeans can be without a specific number or be of a number that is not even or odd? Of course not!

Since Hume bases his doubt of the causal principle on his imagination argument, and the imagination argument is demonstrably false, then it follows that Hume’s imaginative argument does nothing to undermine the certainty of the causal principle in the form whatever begins to exist must have a cause.

A second objection against Hume is that there is nothing in his imaginative scenario that necessitates the billiard ball having no cause—as opposed to a cause that cannot be imagined. Recall that Hume’s argument entails merely imagining the effect without imagining the cause. But perhaps there are causes that by nature cannot be imagined. Such causes could be elementary particles, forces of nature like gravity, or entities that go beyond the material realm, such as God or angels.

If there are causes that are by nature not subject to the imagination, then the mere fact that we fail to imagine them when we imagine an effect (the billiard ball appearing on the table) does not prove that the effect can happen without a cause. It simply demonstrates that the cause of the billiard ball appearing on the table could be something we cannot imagine. If this is true, then Hume’s argument does not achieve what it sets out to achieve—namely, that something can begin to exist with no cause.

Our responses here fall short of proving the metaphysical necessity of the principle whatever begins to exist needs a cause. More philosophizing is required for that! They do suggest, however, that when we think through Hume’s imagination argument, we discover that it fails to disprove the principle. Our atheist friends must find another argument if they want to counter the maxim ex nihilo, nihil fit—“from nothing, nothing comes.”