Pope Leo urged governments to slow down the development of AI systems in the first enyclical of his papacy, warning that they spread misinformation, prioritize conflict and risk leading the world down a path of unending war.
Leo called for ownership of AI data not to be left solely in private hands, for policy-makers to protect the rights of workers and keep children safe from the technology, and urged the cooling of competition between AI companies.
“What is needed is a more active political involvement that is capable of slowing things down when everything is accelerating,” said Leo in the text, entitled Magnifica Humanitas, or, Magnificent Humanity.
The Pope called for “robust legal frameworks, independent oversight, informed users and a political system that does not abdicate its responsibility.”
Invoking the biblical story of the Tower of Babel — where a human tribe is driven by pride to try to create a tower tall enough to reach Heaven, angering God — the Pope said the story shows the risk of any enterprise that “aspires to reach heaven without God’s blessing.”
“With the heart of a shepherd and a father, I ask everyone to abandon the construction of yet another Tower of Babel and to join forces in building up the common good,” he stated.
Leo urged the world not to give up on addressing the possible risks of AI systems.
“A subtle temptation may emerge, namely the thought that the problems are too big and we are too small, and that our choices, therefore, cannot make a difference,” he wrote.
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Spreaking in the Vatican at Pope Leo’s presentation, Anthropic’s Canadian co-founder Chris Olah said the development of artificial intelligence cannot be left solely to technology companies, urging greater oversight from religious leaders, governments and civil society.
Olah said there was “a real possibility” that AI will displace human labour “at very large scale.”
“If that happens, supporting those displaced will be a moral imperative of historic proportions,” said Olah.
Anthropic has been adamant that its Claude AI model not to be used for lethal autonomous warfare without human oversight, or for mass surveillance of Americans. That has led to litigation with Pentagon officials in Donald Trump’s administration
The Pope said any use of AI in warfare “must be subject to the most rigorous ethical constraints” and called it “not permissible” to entrust AI systems with lethal decisions.
Leo, the 14th pope to choose that name, cited centuries of prior papal teachings on social justice issues before addressing the ethics of AI systems.
He specifically invoked his predecessor Leo XIII, who published a famed encyclical in 1891 that called for better pay and conditions for labourers during the Industrial Revolution.
Leo decried what he called “new forms of slavery” endured by people tending AI systems and factory workers who produce the technological devices, such as computers and smartphones, on which AI is used.
“In some regions of the world, children and adolescents work in dangerous conditions, crushing the materials from which rare earth elements are extracted,” he wrote.
“The bodies of these people are scarred, injured and worn down so that computational flow may continue uninterruptedly,” he said. “This reality deeply challenges the moral conscience of our time.”
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Repudiates ‘just war’ theory
Encyclicals are one of the highest forms of teaching from a pontiff to the church’s 1.4 billion members.
The document, which addressed AI as its main theme, also decried the number of wars roiling the world, lamented the weakening of multilateral organizations and warned that arms industry profits were a driving force behind conflicts.
“The past 60 years have been marked by conflicts of astonishing brutality, often affecting civilian populations on a massive scale,” stated Leo, in the English-language text.
“Humanity is slipping into a violent culture of power, where peace no longer appears as a responsibility to be taken on, but as a fragile interval between conflicts,” he said.
U.S. President Donald Trump took shots at Pope Leo XIV on Truth Social after the pontiff criticized Washington’s role in the war in the Middle East. Andrew Chang explains how Trump’s issues with Pope Leo are reaching a new public boiling point.
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Leo also made one of the clearest statements yet from a pope repudiating the “just war” theory, a doctrine the church has used since at least the fifth century to evaluate global conflicts.
The doctrine, which generally says that wars should only be waged in order to defend against aggression, has also been invoked by members of U.S. President Donald Trump’s administration, including Vice-President JD Vance, a Catholic convert, to defend the Iran war.
“The ‘just war’ theory which has all too often been used to justify any kind of war, is now outdated,” wrote Leo.
“The use of force, violence and weapons reflects a relational poverty that always has disastrous consequences for civilian populations.”
Leo also expressed concern that leaders could start wars to distract citizens from domestic issues.
“We cannot rule out the possibility that some leaders may consider armed conflict as an effective way of diverting attention from domestic problems and a cynical tool for managing difficulties,” he stated.
Apology for Vatican’s role in slavery
The Pope also acknowledged that the Catholic Church did not forcefully condemn transatlantic slavery until the 19th century, and made a personal apology.
“This constitutes a wound in Christian memory,” he wrote. “For this, in the name of the Church, I sincerely ask for pardon.”
The Vatican has formally repudiated the 15th-century Doctrine of Discovery, a legal and religious theory that was used for centuries to justify colonial conquests for the sake of spreading Christianity. Indigenous people in Canada have long demanded the move, but some say the church is playing with words.
Past popes have apologized for Christians’ involvement in the trans-Atlantic slave trade. But no pope has ever publicly acknowledged, much less apologized for, the role that past popes themselves played in giving European sovereigns explicit authority to subjugate and enslave “infidels.”
In 2023, the Vatican formally repudiated the Doctrine of Discovery — based on a series of 15th century papal bulls, or decrees, but it never formally rescinded, abrogated or rejected the bulls themselves.
