Pacifism is popular. Many hold that war is unnecessary, since peaceful means of resolving conflict are always available, if only we had the will to look for them. Or they believe that war is wicked, essentially involving hatred of the enemy and carelessness of human life. Or they posit the absolute right of innocent individuals not to be deliberately killed, making it impossible to justify war in practice.

Peace, however, is not simple. Peace for some can leave others at peace to perpetrate mass atrocity. What was peace for the West in 1994 was not peace for the Tutsis of Rwanda. Therefore, against the virus of wishful thinking, anti-military caricature, and the domination of moral deliberation by rights-talk In Defence of War asserts that belligerency can be morally justified, even though tragic and morally flawed.