Bayesian Theology or: How I Learned to Loosen a Doctrinal Death Grip and Love Statistical Thinking

This one comes to us from Rob Munk. Halfway through 2017, I met the woman […]

Guest Contributor / 10.3.19

This one comes to us from Rob Munk.

Halfway through 2017, I met the woman I plan to marry. We bonded over pancakes at a greasy-spoon diner on our first date. She was Anglican; I was Lutheran. It was a match in high-church Protestant heaven. But like many Christian couples, we had our share of theological disagreements, most recently a disagreement on communion theology.

I learned much from the discussion, but my largest takeaway wasn’t even eucharistic in nature. It caused me to question a closely held belief: the belief in my rationality. I realized that I was holding too tightly to my doctrinal beliefs for the evidence available. This doctrinal death grip was a stumbling block to effective communication. After more than a couple exasperated conversations, thankfully I realized I should supplement my theology with Bayesian thinking.

Bayesian thinking is a mental model derived from Bayesian statistics, where hypotheses are expressed as probability statements. For example, a tossed quarter has a fifty-percent chance of landing heads up. This belief is predicated on two things: prior beliefs and data. Prior beliefs can be based on prior data—most quarters are fair. And in the absence of evidence, prior beliefs can be based on assumptions. A quarter has two sides, so maybe landing on either side is equally likely. New data informs our beliefs and allows us to update them accordingly. So while I am generally inclined to think a quarter is fair, suspicion is probably warranted after one-hundred straight tails.

I find Bayesian thinking a useful mental model in addressing theological questions because it allows for examining my beliefs with a degree of emotional detachment. This is important because evidence suggests that emotional attachments make us resistant to facts. So by providing emotional distance, Bayesian thinking allows for appropriate levels of confidence in my theological beliefs, with a greater willingness to correct them.

In the absence of emotional distance, I find myself clinging to even the least-supported doctrines with perfect certainty. In the past, this has blown up in my face and caused a crisis of faith, due to an inability to separate doctrine from faith. Bad theology is concerning, but bad theology held tightly is disastrous. So an appropriate distance from bad theology can help mitigate the damage.

This is not to say that emotions are bad. The shortest verse in the Bible—“Jesus wept”—is wrought with emotion. And the hymns I grew up singing continue to provide emotional support for my faith. But emotional distance allows the freedom to question a doctrine without questioning faith.

Nor do I mean that Bayesian thinking is easy. A lack of good data often leads to bad predictions, and thinking rationally is difficult. For example, two cognitive scientists have found that students are remarkably good Bayesian analysts of familiar topics, but less so of the unfamiliar. They were surprisingly good predictors of box-office grosses, but awful at predicting the length of Egyptian pharaohs’ reigns. And as three business researchers have shown, the human condition often makes rational thinking difficult. Judges are far less likely to grant parole before meal breaks; a judicial lunchtime delayed could be justice denied.

I was certainly not immune to these difficulties. In my better moments, I prayed for wisdom, talked with clergy, read 1 Corinthians 10 and 11 with a receptive mind, and had open conversations with my fiancée. And in my worse moments, I trawled the Internet for the one argument to “destroy” my “opponent,” imposed my own understanding on texts, and approached conversations as opportunities to condescend to the “irrational.”

But I believe persevering through these difficulties was worthwhile. I still hold a Lutheran view of the Eucharist. But I find myself with admittedly less certainty than I desire, which is humbling. This lowered certainty has enabled more fruitful conversations and a more charitable spirit, or so I hope. And by seeking some emotional distance from my theological beliefs, I find myself more able to have emotional connections with the ones I love.