While the origin and development of the just war tradition until the early modern period blended concerns, ideas, and practices from the moral, legal, political, and military spheres, from the mid-seventeenth century until the mid-twentieth it largely disappeared as a conscious source of moral reflection about war and its restraint. Beginning in the 1960s, however, American theologian Paul Ramsey initiated a recovery of just war thinking in a series of writings applying the principles of discrimination and proportionality, ideas he traced (...) both to Augustinian theology and to natural law, to the debate over nuclear weapons and later to the Vietnam War. Ramsey's work directly engaged both theological and policy debate over military force, initiating lines of reflection that have since developed further and become increasingly institutionalized. This brief essay examines the nature of Ramsey's just war thought and its influence over the last 40 years. (shrink)