Karl Barth and H. Richard Niebuhr both attempted to understand the Second World War in theologically realistic fashions. Barth has been termed a critically realistic thinker in recent scholarship, most notably in Bruce McCormack's book: Karl Barth's Critically Realistic Dialectical Theology. Barth uses both realism and idealism to argue against anthropocentric theology, and ethics including traditional just-war theories. He maintains that God must always be primary, the one who determines good and evil; therefore theology and ethics must always to theocentric not anthropocentric. Good is, according to Barth, that which God commands. This leads him to argue for a divine-command ethic in which God speaks to concrete persons in concrete situations. H. Richard Niebuhr, who belonged to the Christian Realists in the United States, argues from a very similar theological basis as Barth, but ends up with an ethics of responsibility rather than a divine-command morality. According to Niebuhr, human beings are responders, who respond in answer to prior action upon them. The primary question for ethics is therefore what is happening, to what must I respond in this situation and how must I respond to it. In attempting to determine the fitting response, one must also attempt to understand what the response to my responding action will be. This model assists in understanding the events that lead up to and occur during war and can help to build a move stable peace. Both Barth and Niebuhr attempted to understand the particular events of the Second World War in a theological and Christian way. Their insights provide assistance in our response to situations that may require the governmental use of force, i.e. military action, peacekeeping missions and humanitarian missions. The world situation, however, has changed since World War II; there are now more and conflicts between non-State groups, such as civil and ethnic wars. Therefore, both Barth and Niebuhr's ethics of the war from that time require some modification to deal with current events. Barth's theological rejection of anthropocentrism remains the framework for any Christian ethic dealing with contemporary uses of military force, but his divine-command morality leaves little room for moral debate and discussion, especially in a multi-cultural setting.