Holy Bayes! When a Math Guy Becomes Pope

Prelude: From Priors to Pontiff

When the white smoke finally curled above St Peter’s, statisticians everywhere refreshed their posteriors—and not just the ones sat on pews. The conclave had elected Robert Francis Prevost, O.S.A., Ph.D. (Mathematics)—author of a 1990 chapter on Bayes’s theorem—as Pope Leo XIV. Twitter promptly collapsed under the weight of jokes that the Church had converged on the MAP (Maximum Apostolic Pontiff) estimate.

So, dear reader, what are the odds of a Bayesian theologian becoming Bishop of Rome? One does not simply divide cardinalities of sets of Cardinals; one does a proper Bayesian update. Let

Since has historically been ≈ 0\%, this posterior was thought to be asymptotic to ε, where ε → 0 faster than Vatican wi‑fi. And yet here we are, posterior probability ≈ 1 —proving once again that rare events are just low‑density regions of the sample space, not impossibilities.

A Short History of Hyperpriors

Prevost’s road from Bayes to Basilica reads like a problem set in stochastic processes:

1. Define state space.
   Ω = {musician, coder, Augustinian friar, professor, Pope, …}.
2. Start at t = 0.
   State: Undergrad math major calculating conditional probabilities of divine providence.
3. Apply random walk with reflecting boundaries (every graduate student knows the feeling).
4. Absorb at Vatican City. The Markov chain hits a closed communicating class; state “Pope” is absorbing—unless you’re keen on Avignon 2.0.

Moral: with a solid grounding in mathematics you can indeed converge to any absorbing state you fancy. Some settle at FAANG; others at Fourier transforms; a lucky ε‑fraction put on the Fisherman’s Ring.

Liturgical L‑Functions

Rumor has it the new Pope is rewriting the liturgy in LaTeX, complete with commutative diagrams for the Sign of the Cross (“In the name of the †, let f : χ → ℝ⁺ be a prior…”). His first encyclical, Credo, ergo Bayes, allegedly proves that simplicity beats spaghetti code in both the Sermon on the Mount and on GitHub.

In Vatican corridors, abbreviations have changed:

One Swiss Guard was overheard muttering, “I signed up for swords, not sigma‑algebras.”

Papal Bull or Random Bull?

The Pontifical Academy of Sciences is thrilled; sports‑book algorithms are furious. Vegas set P(Pope | Bayesian author) at 6 × 10⁻⁷; parlays were annihilated harder than a poorly tuned learning rate. Traders now demand hierarchical models whenever a conclave convenes—no more flat priors on Cardinals under 75 with a Twitter handle.

The After‑Math (pun thoroughly intended)

π‑Times reached out for comment. His Holiness replied via encrypted Matrix (he doesn’t trust p‑values):

“Every belief is a prior; every act of charity an update.”

The papal seal on the message was, fittingly, a conjugate prior.

So the next time someone tells you a math degree is “impractical,” remind them that the job title “Supreme Pontiff of the Universal Church” is technically within the confidence interval. Granted, that interval is ≈ (0, 0 + δ), but as any Bayesian will preach: non‑zero probability plus enough iterations equals destiny.

Now, if you’ll excuse us, we must adjust our priors—because evidently, the Holy See just went open‑source.