Principles of the Just War

Reference: Mount Holyoke College

By Vincent Ferraro

  • A just war can only be waged as a last resort. All non-violent options must be exhausted before the use of force can be justified.
  • A war is just only if it is waged by a legitimate authority. Even just causes cannot be served by actions taken by individuals or groups who do not constitute an authority sanctioned by whatever the society and outsiders to the society deem legitimate.
  • A just war can only be fought to redress a wrong suffered. For example, self-defense against an armed attack is always considered to be a just cause (although the justice of the cause is not sufficient — see point #4). Further, a just war can only be fought with “right” intentions: the only permissible objective of a just war is to redress the injury.
  • A war can only be just if it is fought with a reasonable chance of success. Deaths and injury incurred in a hopeless cause are not morally justifiable.
  • The ultimate goal of a just war is to re-establish peace. More specifically, the peace established after the war must be preferable to the peace that would have prevailed if the war had not been fought.
  • The violence used in the war must be proportional to the injury suffered. States are prohibited from using force not necessary to attain the limited objective of addressing the injury suffered.
  • The weapons used in war must discriminate between combatants and non-combatants. Civilians are never permissible targets of war, and every effort must be taken to avoid killing civilians. The deaths of civilians are justified only if they are unavoidable victims of a deliberate attack on a military target.

Vincent Ferraro is the Ruth C. Lawson Professor of International Politics at Mount Holyoke College.

Additional Readings:

Russell Shaw, “A just pre-emptive attack? Morality of U.S. strike option on Iran debated,” Catholic Online, 3 May 2006

Peter Steinfels, “The Brutality of War, and the Innocents Lost in the Crossfire,” New York Times, 20 November 2004

Garry Wills, “What Is a Just War?,” New York Review of Books, Volume 51, Number 18, November 18, 2004, review of Arguing About War by Michael Walzer
Yale University Press, 208 pp.

George Weigel, “Moral Clarity in a Time of War,” First Things, December 2002

Bishop Wilton D. Gregory, United States Conference of Catholic Bishops, Office of Social Development & World Peace, Letter to President Bush on Iraq, September 13, 2002


MONA FIXDAL, Department of Political Science, University of Oslo, and DAN SMITH, International Peace Research Institute, Oslo, “Humanitarian Intervention and Just War,” Mershon International Studies Review (1998) 42, 283-312

The Internet Encyclopedia of Philosophy, “Just War Theory”

National Public Radio, “A Just War? Asking the Age-Old Question about the Pursuit of Terrorism,” 25 January 2002

J. Bryan Hehir, “What Can Be Done? What Should Be Done?” AMERICA for Oct. 8, 2001

National Conference of Catholic Bishops, “The Church’s Teaching on War and Peace,” 17 November 1993

Kathryn Jean Lopez, “Justice in War: Just-war theory,” National Review Online, 15 October 2001

The Pew Forum on Religion and Public Life, “Just War Tradition and the New War on Terrorism,” 5 October 2001

Richard Falk, “Defining a Just War,” The Nation, 29 October 2001

Howard Zinn, “A Just Cause, Not a Just War,” The Progressive

Peter Steinfels, “Questioning the Morality of Military Attacks on Civilians,” New York Time, 6 April 2002