Can Lethal Autonomous Weapons Be Just?

Lethal autonomous weapons inaugurate a third era of warfare, releasing soldiers from both physical presence and the mental decisions of the battlefield. Their capacity for self-determined action makes them uniquely effective and uniquely unpredictable. Just as the advent of nuclear weapons caused twentieth-century theologians to reassess what constitutes a “just war,” the advent of autonomous weapons in the twenty-first century calls for another such assessment. We will examine four questions which suggest that the use of such weapons is inconsistent with Christian just war theory. First, do such weapons make warfare too easy, and thus militate against it being a last resort? Second, would an AI be capable of acting ethically? If an autonomous weapon is involved in a war atrocity, who is responsible? Finally, how might such weapons be used in situations short of warfare? While a ban on such weapons would be ideal, it is unlikely. In such a case, we can use the traditions of just war theory to ensure autonomous weapons are deployed in a limited and morally responsible manner.