If you're a naturalist like myself you have most likely come to the conclusion that the existence of the universe (or multiverse, if there's more than one universe) is a brute fact. A brute fact is a fact that has no explanation in principle. It's a fact that cannot have an explanation. There are many facts that do not have explanations, but can in principle. These are not technically brute facts, but are just unexplained facts. They can be explained, at least in principle, and many of them will be explained eventually. There is another category of unexplained facts that can be explained in principle, but not in practice. For example, a fact for which all the evidence proving it is destroyed might leave us no possible way to explain it, even though it would be in principle explainable if we just had access to the evidence. These are what you can call epistemic brute facts.
So we have three categories of facts here defined as such: (1) a brute fact: a fact that has no explanation in principle, (2) an epistemic brute fact: a fact that cannot be explained in practice but can in principle, and (3) an unexplained fact: a fact that can be explained both in principle and in practice but simply isn't. In addition to this there are three positions one can take on brute facts: (1) brute facts are impossible, (2) brute facts are possible but they don't exist, or (3) brute facts exist.
Now many theists argue that not only do brute facts not exist, they are in fact impossible. That is, they entail some sort of contradiction that prevents their existence. Many theists will also often try to argue that their worldview has no brute facts, and not only that, they can logically explain their worldview in terms of necessity. This is usually done by some sort of argument that attempts to conclude their god's necessary existence, along with the tacit assumption of the principle of sufficient reason (PSR), which says that for every fact, there is a reason for its existence. Needless to say, the PSR and brute facts are not compatible.
What is an explanation is also important. An explanation is generally defined as a statement or account that makes something clear. It makes something understandable, intelligible. For example, the explanation of the existence of the human species is that we evolved over millions of years from another species of hominids. Explanations tell us the how and why a thing came to be, or exists at all. It is to me an open question whether or not all explanations are causal explanations. In other words, when we say X explains Y, are we always just saying X causes Y? Now I have written that causality exists differently from how it is commonly understood, but on my definition things are still explained in the traditional cause and effect notion. You just have to understand these relationships a bit different.
In this post I'm going to challenge several often heard claims about brute facts. One, that brute facts are logically impossible, and two, that believing in a god allows you avoid brute facts, by arguing that not only are brute facts possible, they are indeed unavoidable.
Claim 1: Brute facts are impossible
A theist I sometimes debate with recently wrote a post claiming brute facts are impossible because he argues, "explanatory chains are essentially ordered series. An essentially ordered series is a series wherein each member derives whatever efficacy it has from higher members--unless it is the highest member--such that if a member is lost, all the lower members will also be lost." I'm going to argue why this is in fact totally absurd. 
For a series to be essentially ordered, the whole chain relies on the existence of the first or highest member, which itself has to either have its own explanation in another thing, or instead be logically necessary. And the claim is that all lower members of the chain derive their intelligibility from the first member.
So this notion that explanations are essentially ordered and that everything in the chain becomes unintelligible unless there is a logically necessary and self explained first member, or that the first member is explained by something else, is absurd. Anyone with basic knowledge of how science works or explanations work knows that you don't have to explain the whole chain in order to make each part intelligible. (The brute fact itself can also be partially intelligible, because if the fact in question is a physical thing, it can be measured and described in terms of age, shape, color, or other characteristics, even without the reason why it exists being known in principle.)
The absurdity of this claim is furthermore supported by the notion of epistemic brute facts. From the perspective of intelligibility, an epistemic brute fact is no different from a brute fact. It is a fact that cannot be explained. If an explanation chain terminates in an epistemic brute fact, we will in practice never be able to explain the first member of the chain, and so why shouldn't all the members of the chain be rendered unintelligible as well? There should be no difference. So if an epistemic brute fact doesn't negate intelligibility of the lower members of an explanatory chain, neither should a brute fact. To say otherwise would have to commit you to the notion that all members of a chain must be understood in order to explain any one part of it. The bottom line is this: explanatory chains are not essentially ordered and if that is the only argument against the possibility of brute facts, it fails to show brute facts are impossible. Brute facts therefore are logically possible because they entail no internal contradiction.
Finally, there are other claims like "everything we know of has an explanation, and if brute facts were true, science would be impossible, so therefore there are no brute facts." Claims like this are wrong on so many levels. First, accepting that brute facts are possible is not saying that most things don't have explanations. They do. When we observe something in the universe, we should always look for an explanation using tools like science. And it turns out, using science, we've been able to understand a great deal about the universe, our planet, and life on our planet. The claim I'm making is that at least one fact has no explanation. This can be true and everything in the universe can have an explanation, in the same exact way everything in the universe can have a cause, but not the universe itself. Science is totally compatible with brute facts existing. In fact, most people claim science can't answer the "ultimate questions" of existence — which I claim are brute facts. Second, just because everything we've been able to explain has an explanation, that doesn't mean everything else will. To say so makes the inductive fallacy, in addition to starting with a circular premise. So claim 1 has no argument that justifies it.
Claim 2: If god exists there are no brute facts
There is a famous trilemma in philosophy called the Münchhausen trilemma which states there are only three options when providing an explanation or proof of a given situation:
- The circular argument, in which theory and proof support each other
- The regressive argument, in which each proof requires a further proof, ad infinitum
- The axiomatic argument, which rests on accepted precepts
But if these properties are all so, then all of god's will and desires must exist timelessly and eternally in an unchanging, frozen state. That would mean that god timelessly and eternally had the desire to create our particular universe, and not some other universe, or no universe. God doesn't think in temporal order, as we do, weighing the pros and cons of each option, with the possibility we could have decided differently. No. God's desire to create our particular universe was eternal and unchangeable, just as his entire mind is. Here's why this is a problem. Our universe is not logically necessary; it didn't have to exist. Every theist would agree with that (that's why they claim god had to create it). But if our universe is not logically necessary then there's no logically necessary reason god had to desire it be created it. Nothing compelled god to do so or even desire to do so. So why then does god exist timelessly and eternally with the desire to create our universe, and not any other universe, or no universe at all, if each of those other options are just as logically possible, and yet also not logically necessary?
Another way to put it more succinctly is this: Why does god timelessly and eternally exist with desire X rather than desire Y, when neither desire X or Y are logically necessary or logically impossible?
Logical necessity cannot explain this scenario. There is no way to show in principle why god had to timelessly and eternally exist with the desire to create our particular universe, and not one just slightly different, or even radically different, or no universe at all. The theist would have to show that it was logically necessary for god to desire to create our universe in order to avoid eventually coming to a brute fact. He can try and say "It's because god wanted a relationship with us," but that wouldn't answer the question at all. Why did god want a relationship with us? Is that logically necessary? Could god exist without wanting a relationship with anyone? And still, even if god wanted a relationship, why did he have to desire this particular universe? There are an infinitude of logically possible universes god could have desired that would allow him to have a relationship with someone else that for no reason god didn't timelessly and eternally exist with the desire to create. A theist can also try to argue that "our universe is the best of all possible worlds, and therefore god had to desire it." But this claim is absurd on its face. I can think of a world with just one more instance of goodness or happiness, and I've easily just thought of a world that's better.
The theist is going to have to eventually come to a brute fact when seriously entertaining answers to these questions. Once he acknowledges that there is no logically necessary reason god had to timelessly and eternally exist with the desire to create our particular universe, and that god could have timelessly and eternally existed with a different desire, he's in exactly the same problem he claims the atheist is in when he says the universe is contingent and could have been otherwise, and therefore cannot explain itself. Hence, even positing a god doesn't allow you to avoid brute facts. There is no way to answer these questions, even in principle, with something logically necessary. They are all going to have to terminate eventually with the honest admission that "it just is," and no further explanation is possible. So therefore, at least one brute fact must exist, and that's exactly my view. Once you admit this, you admit that brute facts are not only logically possible, but logically necessary.
The Münchhausen trilemma, along with this dilemma, show that brute facts not only make sense, they're unavoidable even if we posit god. Thus we could argue more formally:
- The traditional notion of god in classical theism is that of a timeless, changeless, immaterial mind, who also must be infinitely good, infinitely wise, and can do anything logically possible.
- All of god's will and desires must exist timelessly and eternally in an unchanging, frozen state.
- That would mean that god timelessly and eternally had the desire to create our particular universe, and not some other universe, or no universe.
- Our universe is not logically necessary; it didn't have to exist, and god didn't have to create it.
- The theist would have to show that it was logically necessary for god to create our particular universe in order to avoid eventually coming to a brute fact.
- There is no way to answer this question, even in principle, with something logically necessary.
- Thus at least one brute fact must exist even if god exists.
This argument is made even stronger once one considers eternalism and how that makes traditional temporal notions of creation impossible. On eternalism god would have to eternally coexist with our universe, even though our universe's existence wouldn't be logically necessary, and there wouldn't be a logically necessary reason god had to eternally coexist with it. It could have been different. So just as in logic and ethics, in metaphysics you will eventually terminate in a brute fact and no worldview is going to be able to avoid that.
Let me leave you with a joke I just thought of:
Q: Why are brute facts unavoidable?
A: They just are.
 If you've read my critique of chapter 3 of Edward Feser's book The Last Superstition, I quote him as saying a series of causes is essentially ordered if "the later members of the series, having no independent power of motion on their own, derive the fact of their motion and their ability to move other things from the first member". (93)
 It certainly is the case that knowledge of quantum mechanics has helped us understand how stars form via nuclear fusion, but once you scale out to the macro the effects of quantum mechanics give way to general relativity.