PARIS — Pope Leo XIV opened a four-day visit to France on Friday with a warning that artificial intelligence could diminish human dignity and a call to reject nuclear deterrence, which he said risks intensifying the arms race. Speaking at the Élysée Palace alongside President Emmanuel Macron, then addressing diplomats and United Nations staff at UNESCO, Leo argued that technological progress should be judged by how it serves people. He said society increasingly treats computational systems as intelligent while measuring people by efficiency and discarding those deemed unproductive. “To avoid losing our humanity” as machines increasingly shape daily life, Leo said, people need education in ethical judgment and the ability to recognize moral good. He has urged AI developers and political leaders to ensure the technology serves the common good rather than profit. Leo told reporters he hoped dialogue between the Vatican and technology companies would continue, and said AI should remain a tool for people rather than displace or destroy them. The pope also reaffirmed the Vatican’s opposition to nuclear weapons as wars continue in Europe and the Middle East. “Peace is not a balance of power; rather, it is built day by day through dialogue and justice,” he said, calling nuclear deterrence mistaken because it encourages a new arms race. Leo invoked France’s Christian heritage and described the right to life as the foundation of other human rights. The comments land amid sharp disagreement between Catholic leaders and French lawmakers: abortion rights were added to the constitution in 2024, and lawmakers recently gave final approval to a measure allowing some adults with incurable illnesses to receive lethal medication. French Catholic leaders oppose both policies, reflecting church teaching that life must be protected from conception until natural death. The visit is the first official state visit to France by a pope in 18 years. Thousands lined Leo’s motorcade route, and he later led evening prayers at Notre Dame Cathedral, the first pope to celebrate there since the 2019 fire. Macron, who cannot seek a third term in the May election, is hosting Leo as his presidency nears its end. His approval ratings are near record lows amid public anger over living costs, government debt and strained public services.