just war theory is the doctrine that war may be morally permissible under stipulated condi tions. It is a centuries-old attempt to understand how war-an enduring form of systematic killing can be reconciled with our moral presumptionsagainst killing. lt specifies when resorting to war may be morally justified and how armed conflict houldbe conducted to meet the minimal demands of morality. Thomas Aquinas produced the most influential discourse on the doctrine, and
• it has been evolving ever since as both religious
and secular thinkers have tried to• improve it. just war theory has become the most widely used lens through which the ethics of war is viewed these days. As one theorist points out,