Naturalism, Evolution, and Explaining Evil

Let’s take Naturalism to be the thesis that God, or anything at all like him, doesn’t exist. There’s no God, there’s no demons or ghosts. Abstract objects, like numbers and geometrical shapes, don’t exist. Nature is all there is. Some atheists contend that Naturalism is a good explanation for suffering and evil. They claim it explains atrocities like child molestation, rape, and the Holocaust. Let’s take a further look at Naturalism, Evolution, and explaining Evil.

In a recent exchange on the topic, it was argued that Naturalism explains a wide range of data. When pressed on this, the atheists punted to evolution: Evolution leads us to expect humans to act in ways that further reproduction and survival, not necessarily ways that promote moral behavior. Here’s what is meant by Evolution:

The Earth is billions of years old.
Offspring differ in small ways from their parents.
All living organisms share a common ancestor.
There is a mechanism driving this process – e.g.: natural selection.

The atheists above weren’t saying that Naturalism explains the data, but rather that Naturalism & Evolution explains the data. Evolution to the rescue! Here are 3 reasons Evolution is not Naturalism’s savior.

1. Naturalism doesn’t predict Evolution.

First, nothing about Naturalism (so defined) actually predicts Evolution. Naturalism is perfectly consistent with Evolution being false. Why is this a bad thing? Well, if this is true, Naturalism suffers from what Robin Collins calls probabilistic tension:

A hypothesis h suffers from probabilistic tension if and only if h is logically equivalent to some conjunctive hypothesis, h1& h2, such that either P(h1| h2) << 1 or P(h2| h1) << 1: that is, one conjunct of the hypothesis is very unlikely, conditioned on the other conjunct. Among other things, a hypothesis h that suffers from probabilistic tension will be very unlikely: since P(h) = P(h1& h2) = P(h1| h2) x P(h2) = P(h2| h1) x P(h1), it follows that if P(h1| h2) << 1 or P(h2| h1) <<1, then P(h) << 1.

In our case, Naturalism represents h. If h is really the conjunction of Naturalism & Evolution, then we can represent Naturalism as h1 and Evolution as h2. Since the probability of Evolution on Naturalism is very, very low [1], the probability of h2 given h1 is very, very low. Following Collins, this leads us to conclude that the prior probability of h is extremely low.

This conclusion is highly significant. Atheists do not usually want to admit that the prior probability of Naturalism is low. In fact, some think it much higher than Theism (see Draper). Another key point here is that a low prior could negatively outweigh any confirmation that evil and suffering gives Naturalism. So even if Naturalism explains the data of evil and suffering apart from Evolution (of which I am dubious), Theism could still have a much higher posterior probability.

2. Don’t we just know it?

Suppose the Naturalist sees this problem and decides to reorganize their equation. Instead of adding Evolution to Naturalism as a theory, they decide to add Evolution to our background information (in other words, they’ll say Evolution is common knowledge to everyone; it’s something we all know to be true). Voila! Problem solved. Right? Wrong.

If Evolution is part of the knowledge we bring with us, then every hypothesis explains the data. Why is that? Recall that Evolution was originally introduced in order to explain evil and suffering. Since Naturalism can’t explain anything, it’s actually evolutionary pressures (like reproduction and survival) that explain the data. However, if Evolution is common knowledge, if it’s true regardless of the theory we’re testing, then the data of evil and suffering is expected on every hypothesis (since evolution is in the background). But if the data is equally explained on every hypothesis, there’s no way evil and suffering can be evidence for Naturalism over Theism.

3. Why not add Evolution to Theism?

The third problem is that, if the Naturalist can add evolutionary theory to Naturalism, why can’t the Theist do the same? Responding by saying, “God probably wouldn’t use Evolution,” won’t work. Even if Evolution is unlikely on Theism (e.g.: God didn’t have to use Evolution), the same is true for Naturalism. Even in the small subset of Naturalistic worlds that contain biological life, Evolution wasn’t needed to bring it about [2]. Thus, if the Naturalist can make use of Evolution, why can’t the Theist? To suggest otherwise would be a clear case of special pleading.

Essentially what’s going on here is that the Naturalist is giving a coherent Naturalistic story that explains evil and suffering. I’m saying the Christian can do the same thing, using the same theory. Evolution and Christianity are compatible in the same way that Evolution and Naturalism are compatible [3].


Since Naturalism can’t explain anything, some atheologians feel forced to introduce evolutionary theory into their arguments from evil. This creates probabilistic tension for Naturalism and hence severely lowers its prior probability. Second, adding Evolution to our shared background knowledge won’t work because then every hypothesis, including Theism, explains the data. And third, if nothing else, the Theist could just add Evolution to Theism and the problem of evil vanishes.

Not every atheological argument from evil falls prey to these considerations. However, those that do have some explaining to do.


[1] This follows for a number of reasons. I’ll list two. First, Naturalism is consistent with evolution being false. Coherence raises epistemic probability. Second, there are plenty of Naturalistic worlds without life and hence without evolution. Given the fine-tuning argument, this probability is almost incalculably low.

[2] For instance, biological life could exist as a brute fact on Naturalism.

[3] I’ll just add that the Christian has other consistent propositions (like Trans-world Depravity, Soul-Building, Supralapsarianism, etc.) they could add to Theism that would equally predict evil and suffering.

About the Featured Image
Taken in San Francisco. Not much else to say about this one other than it seemed like the archetype of San Franciscan architecture. You may notice some reflections. It was taken out of a moving bus.



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Thanks for this Cameron, I found this very helpful. After watching the discussion you engaged in, I found myself frustrated by their claim “Naturalism predicts x better than Theism does” I just find that contention bizarre. If that was the case, surely under ANY state of affairs the Naturalist could make that assertion and if that is the case then surely naturalism predicts nothing? Am I wrong here?

Regardless, thanks for this post and your ministry! 🙂


Cameron, It’s unlikely you’ll see this comment because this is an old post, but I’d like to offer some comments. “Coherence raises epistemic probability.” Only in a trivial sense. It eliminates a probability of 0, but coherence doesn’t purchase you anything other than a non-zero probability. “Second, there are plenty of Naturalistic worlds without life and hence without evolution. Given the fine-tuning argument, this probability is almost incalculably low.” This is your real argument. This really depends on how we spell out the fine tuning argument. Some defenders of the fine tuning argument say (rightly, I believe) that fine tuning… Read more »