Theism vs Atheism: Which Is Simpler?
I take *the* argument for atheism to be this.
1) If two theories explain just as much, believe the simpler.
2) Atheism and theism explain just as much.
3) Atheism is simpler.
4) Believe atheism.
There is much to say about this.
Let’s start here.
Obviously, if it can be metaphysically demonstrated that God exists, then appeals to simplicity aren’t going to do much, because in virtue of that demonstration premise 2 is false (i.e., atheism can’t explain “History” whereas theism can).1 Put that aside: a different conversation for a different day.
More to the point, atheism is not just the view that the world exists. Atheism is the view that the world exists AND lacks God. So, whereas theism posits A and B (world and God) atheism posits A and NOT-B (world and NOT-God). As Tim McGrew explains, because there are no general rules of probability theory that tell us the probability of A and B is less than A and NOT-B, everything depends on specifics.2 In short, this renders the simplest form of atheism AT LEAST as complex as the simplest form of theism.
If the atheist wants simply to appeal to having a leaner ontology — that is, having fewer things bumping around — this isn’t ultimately going to help (at least not when considered in an evidential vacuum) because stripping down one’s ontology doesn’t necessarily increase simplicity in the relevant sense of making a worldview more reasonable.
Consider the following illustration (modified from McGrew): Take everything everything the naturalist believes exists and subtract Bill Clinton. This theory is leaner, ontologically speaking -- that is, it has fewer existing entities -- but now to explain things equally well the “No Bill Clinton” theory becomes less “simple” because it is forced to adopt auxiliary hypotheses to increase predictive and explanatory power (for example, invoking convoluted conspiracy theories, hence introducing more ways things could go wrong). In which case having a leaner ontology does not automatically translate to having a simpler (read: having less ways of going wrong = intrinsically more probable) theory.
The atheist may retort that Bill Clinton is not a fundamental feature (or entity) and considerations regarding simplicity must be focused there. But this puts the atheist in no better a position because it is not clear that naturalism actually does posit fewer FUNDAMENTAL features than theism. This, of course, depends on the brand of naturalism at play. However, Classical theism is hard to beat in this respect, since it only posits one (supremely simple) fundamental feature: God.
As Kenny Pearce explains, “According to the naturalist, there is only one kind of fundamental stuff, physical stuff. God, however, is not physical, so the theist has fundamental physical stuff plus God, which is extra complexity. This, however, is a mistake. According to the version of classical theism I’ve developed, the physical is grounded in God who is the only truly fundamental entity. So at the most fundamental level, this view not only has only one kind of thing, it has only one individual thing, namely, God. If the naturalist objects that I have introduced a new layer in the grounding hierarchy, this is quite correct, but when we introduce a more fundamental layer of reality that unifies and explains the layers to which we were already committed, this is not an increase in complexity. As a result, it is actually not clear that the naturalist has any advantage in simplicity at all.”3
Worse for the naturalist is this: numerous naturalists posit multiple ontological primitives rather than adopt for priority monism, often accepting a slew of “brute necessities.” If they take this option, then it is even more difficult to see in what sense naturalism has any advantage with respect to ontological simplicity over theism; in fact, it seems it is decidedly less simple regarding fundamental entities. Other naturalists may opt for priority monism and say spacetime is fundamental (and necessary,). This is problematic for multiple reasons, one of which is that it is incompatible with the most straightforward interpretations of general relativity (which gives reason to think spacetime is neither fundamental nor necessary, particularly in its geometric structure), which is bad news for any naturalist who believes (as most naturalists do) that naturalists ought form their metaphysical theories from the best contemporary science.
Really it should be uncontroversial to say theism predicts/explains the most with the least. God, in virtue of being purely actual (maximally great, no restrictions or arbitrary limits, etc.), can explain the existence of knowledge and power and goodness. Also the existence of beings like us (rational/moral agents). God has the “in-built” resources to do that.
Does atheism make similar predictions? Atheism is just the hypothesis that there is no God (or anything like God). I.e., there is no perfect or supreme foundation to reality, as Joshua Rasmussen would put it. We ask: What does that predict? To my mind, nothing — literally nothing. Thus, to pick up predictive/explanatory fruitfulness, the atheist must begin adding components to their root theory, increasing complexity to make their hypothesis an explanatory rival to theism. (Note: If “atheism” is not proposed as an explanatory rival but just an insistence on someone’s non-belief of God, then who cares? What concerns us here is how to compare the relevant probabilities between large-scale COMPETING theories of reality.)
Clarifications before proceeding:
What do we mean by predictive and explanatory success, reasonable degree of expectation, and so on? What we mean is that in analyzing the evidential weight in support of rival theories, we are using the tool of Bayesian probability, which Joshua Rasmussen helpfully summarizes:
“For any given data D and hypothesis H, we can investigate whether D supports H by asking two questions:
Q1. How likely (expected) is D given H?
Q2. How likely (expected) is D without H?
If D is more likely given H than without H, then D supports H.”4
For example (again borrowing from McGrew), imagine the following. You are walking in the woods and stumble upon what appears to be an abandoned cabin. The outside looks decrepit: there is moss, the front door is barely hanging on, and whatever else. But then you peer inside and notice that there is a cup of tea steeping. Immediately, you revise your hypothesis from the cabin being abandoned to the cabin being occupied. Why? Because a steeping cup of tea is better predicted and explained by—that is, far more probable on—the hypothesis that the cabin is occupied, notwithstanding the cabin’s condition.
Here is an important feature of this line of reasoning. It does not matter if you cannot assign a specific probability to the likelihood that any given occupied cabin will have a cup of tea steeping in it. It also does not matter if you think the probability of such an occurrence is low or even exceptionally low. What matters is what you believe the probability to be of finding a cup of steeping tea in an occupied cabin versus an abandoned one—for even if you believe that the probability of finding steeping tea is low in any given occupied cabin, surely the probability is far lower in any given abandoned cabin, whatever those specific probabilities are.
So the discovery of steeping tea in any cabin gives great evidence for that cabin being occupied rather than abandoned—in fact, such great evidence that it causes you to be virtually certain that the cabin is occupied. The steeping tea didn’t come about from a fortuitous set of non-intelligent circumstances, like wind blowing plus an earthquake and a lightning strike.
With that illustration in mind, consider the following features of reality which we have good (if not undeniable) evidence for:
- Concrete (causally-capable) things
- Moral principles
- Reasoning principles
- Orderly laws
- Complex (and quite elegant!) structures
- Physical fine-tuning
- Consciousness
- Love
- Knowledge
It also has evil.
Atheism doesn’t predict anything of these things; theism either 100% predicts (or makes relatively unsurprising) all of them. In which case our encountering these features is evidence for theism, not atheism (including evil, as I argue in the linked article).
What can the atheist do? They can ADD to their theory and say things like, “Let’s include physical laws like the ones we observe, and principles of logic like the ones logicians discuss, and moral principles like the ones ethicists identify, and let’s embed consciousness while we’re at it because we shouldn’t want to be eliminativists!”
Or maybe the atheist will say, “Hold on. You have God and the world. We just have the world. You can’t take the world away from us!”
Here it is critical to distinguish the data to be explained from the theory that explains it. “The world” refers to some possible state of affairs and by itself predicts/explains nothing because it doesn’t say anything EXCEPT (for the atheist) that it doesn’t include God. However, God’s inclusion makes it unsurprising — in fact, 100% predicts — that something concrete (and causally capable) exists in “the world” and not nothing instead. Does atheism do this? No. Why would it? The atheist must begin filling out their theory to provide an explanatory account for why concrete causally capable things DO exist (etc), adding complexity to their root theory of God’s negation.
The takeaway is this. The natural world that we experience (the data to be explained) is unsurprising if God exists (the theory that explains it), in which case this counts in favor of theism. Any version of atheism that explains as much as theism (assuming this can be done; I maintain that it can’t be) will inevitably be more complex (= less intrinsically probable), like the conspiracy theory required to make up for the non-existence of Bill Clinton.
This sets up the theist for the following:
1) If two things explain (or predict) things equally well, believe the simpler.
2) Atheism and theism explain things equally well only if atheism is supplemented with (vastly) greater complexity.
3) Believe theism.5
See: http://writings.kennypearce.net/foundationalGrounding.pdf
See: https://www.amazon.com/Four-Views-Christianity-Philosophy-Counterpoints/dp/0310521149
Is There a God: a Debate
https://joshualrasmussen.com/articles/problem-of-evil-response.pdf
I thank Joshua Rasmussen for providing this suggestion in a private email exchange.