Pope Leo XIV Calls for New Moral Rules on AI-Driven Warfare

In his first encyclical, Pope Leo XIV argues that autonomous weapons threaten human dignity and urges that lethal decisions remain under accountable human control.

Pope Leo XIV’s inaugural encyclical, Magnifica Humanitas, confronts the ethical hazards posed by autonomous weapons and artificial intelligence in modern conflict, asserting that such technologies erode human rights and dignity. The text references a Holy Week visit by a priest to a Ukrainian drone unit near Zaporizhzhia, where holy water was sprinkled on a Gara strike drone before it was piloted against Russian positions, highlighting the uneasy fusion of faith and machine.

Leo critiques the traditional just-war framework as outdated, urging a revised doctrine that accommodates mediated warfare while preserving core principles like legitimate authority and proportionality. He calls for a verifiable chain of responsibility linking designers, trainers, and commanders, mirroring the Pentagon’s Responsible AI Strategy but demanding stricter human oversight. The encyclical also warns against allowing speed and efficiency to dominate lethal decision-making, insisting on a “moral timeframe” for accountability.

At an extraordinary consistory, Cardinal Víctor Manuel Fernández reported that some cardinals view just-war theory as a justification for conflict, prompting discussion of a narrower “proportional defense” concept, though Leo stressed further theological refinement is needed. The document seeks to engage military ethicists, engineers, and policymakers to embed ethical safeguards before autonomous systems are fielded.