In this, the first major philosophical study of contingent pacifism, Larry May offers a new account of pacifism from within the Just War tradition. Written in a non-technical style, the book features real-life examples from contemporary wars and applies a variety of approaches ranging from traditional pacifism and human rights to international law and conscientious objection. May considers a variety of thinkers and theories, including Hugo Grotius, Kant, Socrates, Seneca on restraint, Tertullian on moral purity, Erasmus's arguments against just war, and Hobbes's conception of public conscience. The guiding idea is that the possibility of a just war is conceded, but not at the current time or in the foreseeable future due to the nature of contemporary armed conflict and geopolitics - wars in the past are also unlikely to have been just wars. This volume will interest scholars and upper-level students of political philosophy, philosophy of law, and war studies.