Notes on Pope Leo XIV’s encyclical on AI

Simon Willison’s Weblog

Subscribe

Sponsored by: exe.dev — ssh, root, https. Real VMs, not sandboxes. Edge-injected secrets so you can yolo. 0→1? ½→1!

Notes on Pope Leo XIV’s encyclical on AI

25th May 2026

Dropped this morning by the Vatican: Magnifica Humanitas of His Holiness Pope Leo XIV on Safeguarding the Human Person in the Time of Artificial Intelligence. This is a very interesting document. It’s some of the clearest writing I’ve seen on the ethics of integrating AI into modern society.

Pope Leo XIV chose the name Leo in honor of Pope Leo XIII, who is known for his 1891 Rerum novarum encyclical on “Rights and Duties of Capital and Labor”.

This story on Vatican News further clarifies the significance of that decision:

Meeting with the College of Cardinals for their first formal encounter after his election, Pope Leo XIV explained part of the reason for the choice of his papal name. "There are different reasons for this," he said, before going on to explain that he chose the name Leo "mainly because Pope Leo XIII, in his historic encyclical Rerum novarum addressed the social question in the context of the first great industrial revolution."

“In our own day,” he continued, “the Church offers to everyone the treasury of her social teaching in response to another industrial revolution and to developments in the field of artificial intelligence that pose new challenges for the defence of human dignity, justice, and labour.”

And now we get Pope Leo XIV’s own encyclical on the AI revolution. There’s a lot in here, but the writing style is very approachable, including to non-Catholics.

A few of my highlights

(I listened to most of the encyclical on a walk with our dog, my first time trying the ElevenReader iPhone app. It worked very well: I pasted in a URL to the document and it read it to me in a very high quality voice, highlighting each paragraph as it went.)

Here are some of my highlights. In each case below emphasis is mine.

Here’s a useful description of the interpretability problem for LLMs in section 98:

First, any statement regarding AI risks becoming quickly outdated, given the remarkable pace at which these systems are developing. Second, all of us, including those who design them, possess only a limited understanding of their actual functioning. Indeed, current AI systems are more “cultivated” than “built,” for developers do not directly design every detail, but instead create a framework within which the intelligence “grows.” As a result, fundamental scientific aspects — such as the internal representations and computational processes of these systems — remain, at present, unknown.

I liked section 83’s description of the relationship between development and dignity:

For individuals as well as for nations, development is both a duty and a right. Minimum conditions are required for enabling every person and people to flourish in accord with their dignity, without being kept in a state of dependence or excluded from access to necessary goods. Development is truly human when it places people at the center instead of the accumulation of wealth, and when it concerns peoples as well as individuals. Justice demands the recognition of the rights of society and the rights of peoples, and includes a responsibility toward future generations. Development is not truly human if it increases consumption for some while shifting costs and burdens onto others, or relegates entire regions to subordinate roles, preventing them from realizing their full potential .

Baked in cultural biases and sycophancy get a mention in section 100:

In personal use, three aspects in particular deserve careful consideration: the ease with which results are obtained, the impression of objectivity and the simulation of human communication. The speed and simplicity with which information, complex analyses, media content and practical assistance can be accessed undoubtedly makes life easier. Yet they can also encourage excessive reliance and the search for ready-made answers, and weaken personal creativity and judgment. The apparent objectivity of the responses and suggestions these systems provide can lead us to overlook the fact that they reflect the cultural assumptions of those who designed and trained them, with all their strengths and limitations . The artificial imitation of positive human communication — words of advice, empathy, friendship and even love — can be engaging and at times genuinely helpful. However, for less discerning users, it can also be misleading, creating the illusion of a relationship with a real personal subject . When words are simulated, they do not build genuine relationships, but only their appearance. The artificial imitation of care or support can become particularly risky when it enters contexts where real relationships and emotional bonds are lacking.

101 touches on the environmental impact:

Current AI systems require enormous amounts of...