Do Atheists and Theists have the Same Burden of Proof?

How historic shifts in default assumptions have stacked the deck against theists

If I told you I have a trillion dollars in my bank account, would you take my word for it or would you require some more evidence to back up my claim? Suppose I told you instead that I have a five-dollar bill in my pocket. Would you trust me then rather than harboring a doubt?

What’s the difference between those two cases? It’s that the first one is out of the ordinary, while the second is commonplace. There’s nothing strange about someone living in a developed country such as Canada and having a five-dollar bill in his pocket. You’d have no trouble believing that, just as you wouldn’t go out of your way to doubt that the grass is green or that you can buy food at the local supermarket.

Indeed, you couldn’t doubt every part of your normal experience without lapsing into insane paranoia. Even if you wanted to doubt what seems obvious, assuming you have a healthy brain and upbringing, you’re much more inclined to take some things for granted and to spend your mental resources pondering more novel scenarios on the frontiers of your experience.

That’s how informal reasoning and critical thinking work: we distinguish between the core and the periphery of our experience, and we assign different probabilities to events depending on how well they conform to the core which we take as our default set of assumptions. Grass is green, the sky is blue, and I can have five dollars in my pocket. Those are truisms, and if you spent any time doubting them outside of a philosophy class, you’d have too much time to spare.

But no one has proven to anyone else that he or she has a trillion dollars. We know of millionaires and even billionaires, but not of trillionaires. Having a trillion dollars would be virtually miraculous, which is to say that this event would be highly unusual — so unusual in fact that your first reaction to its possibility should be to scoff at it. “Yeah, right,” you’d say. “You have a trillion dollars. Nice joke, but what’s the punchline?”

The Religion of Trillionairity

Suppose, however, a cult arises and worships what its members take to be a hidden trillionaire. The members of this cult were somehow led to believe that there is in fact a trillionaire out there somehow. Perhaps someone dreamed once of this fantastically wealthy individual and decided to trust in that dream as a special revelation. And perhaps that believer has great rhetorical skill and can persuade others to take that dream seriously.

Thus, a religious movement called “Trillionairity” takes off. Trillionairist parents teach their children to worship the hidden trillionaire because one day that trillionaire will share his enormous wealth with the believers. The more you trust in the trillionaire even without proof there’s any such fabulously wealthy person, the more appreciative the trillionaire will eventually be.

Now if I happened to encounter a third-generation Trillionairist, and I told her that I have a trillion dollars in my bank account, she wouldn’t likely scoff at that assertion. Perhaps she’d be cautious since she might suspect there are false prophets out there preying on the faith of fine Trillionairists. But she wouldn’t dismiss the possibility the way a non-Trillionairist would because she’s been led to believe there is in fact a trillionaire.

This most wealthy individual is supposed to be hidden, and the odds of anyone meeting the trillionaire would be low (roughly one in eight billion). So perhaps the Trillionairist would be taught to form a “T” with her hands, as a symbol to show that while she takes the trillionaire’s existence seriously, she’s not one to fall for false prophets.

Suppose, though, I rig a bank website to show that I have a trillion dollars. Perhaps at this point the Trillionairist would begin to believe that a blessed event had occurred, that she’s met the object of her religious faith. Yet if I tried the same trick on a non-Trillionairist, that person would be less inclined to fall for it because he or she wouldn’t have been programed to accept a pro-trillionaire belief as one of her default assumptions.

Burden of Proof and Default Assumptions

I trust you see the parallel between Trillionairity and theistic religions. And this is roughly all you need to know to understand the atheist’s burden of proof. That burden is relative to what’s assumed as self-evident or as common knowledge. Some assumptions are universal in human experience, while others are more controversial, depending on the period, the level of social development, and an individual’s upbringing.

Trillionairists and critics of that religion would have different default assumptions. For precisely that reason, it would take less to convince the former that I have a trillion dollars than it would to convince the latter. That is, the Trillionairist would have a lower epistemic threshold for believing there could be a trillionaire than would anyone who hadn’t been raised in that odd religion.

Mind you, Trillionairity seems odd to everyone else, but not to its practitioners. That oddness is just a reflection of the relativity of the burden of proof.

So the atheist’s burden of proof depends on which assumptions we’re taking for granted. If a Christian, say, wants to prove to a Muslim that God exists, the Christian won’t have to strain her mental faculties, because the Muslim is predisposed to accepting that conclusion. This would be like pointing out to someone that the grass is green. Stating the obvious might even be offensive because you’d be indirectly insulting the other person’s intelligence. If a Christian tries hard to prove to a Muslim that God exists, the Christian might be implying that the Muslim’s faith is empty or that she’s effectively an atheist.

In any case, when a Christian tries to prove God’s existence to an atheist, she knows she has an uphill climb since the atheist doesn’t share the Christian’s default assumptions about how the world works. Likewise, the reverse is true: if an atheist tries to show a Christian there’s no God after all, she knows she’ll have to muster more evidence than she’d have to bring to bear were she instead talking to a fellow atheist.

Conversations are difficult between people who lack much common ground.

Stacking the Deck Against Theism

All of which should be evident. The more interesting philosophical question is whether there’s enough common ground between theists and atheists to warrant an asymmetry in the kinds of evidence they need to rationally support their opposite conclusions. Or would you have to beg the question at issue to take either theistic or atheistic experience as central to humanity or as definitive of objectivity?

Atheists often say there’s an absolute difference in the burden of proof because of the logical nature of the claims. Theists must prove a positive, whereas atheists would be proving a negative. But that logical difference seems superficial since you can reword either claim as positive or as negative. Instead of saying that God exists, the theist can say that naturalism is false, which would amount to negative theology. And instead of saying there’s no God, the atheist might say that only the natural universe of finite, contingent things exists.

So is atheism essentially a negative claim and is that what would be crucial to establishing the atheist’s burden of proof? The atheist wants to say that the atheist wins by default, since the one making the positive claim has the burden to support that claim, like in a court of law. The atheist is in the defense lawyer’s position of only having to refute that positive case, not to provide an alternative explanation.

But the reason for that asymmetry in a court of law is practical, not logical. Democracies are based on modern skepticism about governments and on fear of tyrannies, so the government takes on the added burden in prosecuting an alleged criminal. Stacking the deck in a comparable way for theists and atheists might indeed make for fallacious circularity.

Even if, say, the Scientific Revolution has proliferated doubts not just about governmental overreach but about superstition, theocracy, and all things religious, using that historical fact as a reason to think theists have the greater epistemic burden is to presuppose atheism. Anyone who’s been sufficiently affected by modernity to agree with that difference in the burden of proof would already be an atheist, in which case there would no longer be a dispute about God’s existence.

Of course, theists are precisely those who, for one reason or another, have been sheltered from those modern influences. They don’t begin their reasoning from a standpoint of skepticism towards religion as such — even if they make a dubious exception of their home religion and dismiss all the others as demonic parodies.

The Irrelevance of Proof in Nature

Returning, then, to the point of logic, the difference is supposed to be that proving a negative would be practically impossible since you’d have to confirm there’s no X by checking everywhere in the universe.

But as I explain elsewhere, that kind of proof is irrelevant in determining whether something exists in the real world. We must be content with playing the odds based on induction, and with accepting something’s existence as probable at best, because the real world isn’t game-like. We don’t get to stipulate the rules that nature has to live by, so when confronting nature, we’re in no position to reach for the definitive judgments we’re used to making when playing games like chess or when we’re reading a novel.

We know exactly what happens in a fictional story because the author gets to stipulate the content. By contrast, our mental models of what’s out there in nature are crude humanizations of a domain that evidently outstrips the limits of our intuition. Concepts don’t mirror natural facts so there can be no absolute agreement between the two. The relationship between intelligent organisms and the rest of nature is far messier than that happy arrangement of mirroring or of agreement would suggest.

Yet perhaps that distinction between fiction and reality also begs the question. If the theist were to agree that nature seems mostly inhuman, with respect to the astronomical scale of outer space and of deep time, wouldn’t she already be in danger of losing her religious faith? Isn’t the theist committed to saying instead that the universe’s evolution is just a story told by God, that “nature” is artificial because God made it all?

The Atheistic Upshot of Commonplace Scientific Revelations

Here, though, we seem to arrive at some troubling common ground, after all. Only the most remote theists, such as perhaps those living in Afghanistan who reportedly were unaware even in 2011 that the 9/11 attacks occurred in the US — only such lamentably uninformed theists would be unaware of the earth-shaking scientific discoveries of the universe’s inhuman scale. Surely almost all adults in 2021 are aware that the universe extends far beyond our solar system, that there are many galaxies that exist just like ours.

Yet that independently established fact alone does tilt the scales in atheism’s favour. The obvious theistic response is that the universe’s inhuman, literally unimaginable scale is consistent with God’s magnificence. But notice that if God were so magnificent that “he’d” be in no way like a mere human person, believing that this “God” exists would be consistent with atheism!

Theism requires some similarity between humans and the universe’s ultimate source; as the Book of Genesis says, we were made in God’s image. Yet that similarity is just what commonplace scientific discoveries have undermined. The upshot of science has been an overturning of anthropocentrism. So if we can learn about God’s nature from his handiwork, and the universe is inhumanly vast and complicated, God must be likewise inhuman — which is to say that this “God” is no God at all, or at least no deity worth trusting.

Why establish a religion on trust in a wholly alien being whose creation is unfathomably superhuman and whose nature is beyond our comprehension in all respects, making nonsense of every religious metaphor and myth? That Lovecraftian religion would be only a step away from atheism.

The point is that if atheists have a lower burden of proof not because their claim is logically negative but because scientific advances have changed the default assumptions in epistemology, this does amount to saying that atheists no longer need to work so hard because science has already discounted at least the more naïve, literalistic theists’ conceptions of God.

The God that created the universe that’s studied by modern scientists would not be the deity worshipped by most religious people in history. Their deity is an anthropocentric projection, whereas the natural universe is an ongoing belittlement of human nature. Instead of pretending that reality can fit inside our head, our existential burden is to cope with the traumatic realization that we evidently don’t belong in the universe.

We’re preoccupied with relatively small-minded, social affairs, as mammals that evolved for that purpose, whereas the universe is on a mind-boggling trajectory that makes human history in its entirety seem like a knock-knock joke or like a trivial game of Tic Tac Toe. We’re like the first quasi-fish that began to walk on land. We awoke to the wider world, thanks to the accidents of our consciousness, intelligence, and autonomy. As people rather than animals on earth, we’re interlopers, aware now that reality ranges far beyond anything we can reasonably call “home.”

Theists, too, must reckon with those newly established, commonplace empirical facts. They must reconcile themselves to the evident monstrosity of their so-called “God.”