The Causes of Peace

The terms war and peace can relate to many dimensions of society. This essay examines very briefly the causes of peace in the international state system: war and peace within states (intrastate conflict) and between states (interstate conflict).

Political scientists normally do not ask the question what causes peace. They normally address the issue from the other end: What causes war? If we can learn more about this, then we are more apt to begin to answer the question about the causes of peace.

Traditional theory of international relations gives various explanations or theories about war and peace. The most famous is balance of power theory and what political scientists call political realism. In this theory of realism:

  • World politics is a world of anarchy. There is no world government which has sovereignty.
  • Because of this, states–the most important actors–must look after themselves.
  • The interests of the state, rather than moral principles, always come first. Survival is the most important self-interest.
  • They do this mainly by seeking power, by accumulating more power than other states.
  • In behaving like this, they normally follow the rule: the end justifies the means.

UN Security Council

This theory suggests that for war to break out, there must be an imbalance of power in the international system. A state accrues too much power, e.g., France under Napoleon in the early 19th C, or has too little power, e.g., Kuwait in 1990, when Iraq attacked and occupied it.

Then for peace to “break out,” the theory suggests that there must either be a state with overwhelming power, like Rome in the 2nd century or the U.S. in the 1990s, or a system of states where power among the states is relatively balanced, like the Cold War period 1947-1991, between the US-led NATO alliance and the USSR-led Warsaw Pact.

Achieving balance and stability is critical. In his book, The Peloponnesian War, Donald Kagan discusses the Thirty Years Peace, between Athens and Sparta in the 5th century BCE. He addresses three different types of peace treaties.

  1. Some end in one side being totally destroyed, e.g., Carthage in the Punic Wars, (and perhaps the native Americans in the war for the American West).
  2. Other treaties inflict harsh terms on a defeated enemy but do not extinguish it, e.g., Prussia’s defeat of France in 1871, the Allies defeat of Germany in World War I. The loser, in this case, may seek revenge. After the punitive Versailles Treaty the Allies forced Germany to sign after WW I, Hitler referred to this “dictated peace” often and used it to stir the emotions of the German people.
  3. The third type ends a long and costly conflict in which the sides have recognized the great costs of the war and in which there is no genuine victor, for example, the Peace of Westphalia in 1648 ending the Thirty Years War or the Congress of Vienna ending the Napoleonic Wars in 1815. This last type seeks to reestablish an enduring order and stability. While there were many wars and revolutions after 1815, there was no general war involving all the major European powers until World War I in 1914.

Recent scholarship on war and peace gives grounds for optimism. In his book , The Better Angels of Our Nature: Why Violence Has Declined, Steven Pinker presents such data. Interstate wars have declined. The last one was the US-Iraq War in 2003. Moreover, since World War II, the deadliness of wars has also declined. Pinker points out that in 1950, the average conflict (of any kind) killed 30,000 people. In 2007, it killed less than 1000. Also, intrastate conflict or civil wars and other conflicts have also declined. The annual rate of battle deaths has dropped from almost 300 per 100,000 of world population during WW II to fewer than one in the 21st century. And we have not seen an increase in civilian deaths with this drop in battle deaths. The ratio has remained the same:  about 50-50.

What are the causes of this drop? Pinker offers several reasons or theories. First, he says that war no longer pays. The costs outweigh the perceived benefits. Second, while there is no sovereign world organization or uniform set of international laws, happily we have a more regulated international system. The United Nations is a bigger player than in the 20th century and has sent peacekeeping missions to many areas. Third, we have witnessed in the past 60 years an increase in trade and prosperity. Today more wealth comes from trade than conquest. Lastly, there has been a “growing repugnance” to and rejection of “institutionalized violence.” Perhaps the human qualities of self-control, reason, and empathy are winning out over greed, revenge and the lust for power.

In an online article in Current Anthropology on October 13, 2017, Dean Falk and Charles Hildebolt challenge Pincker’s conclusions. In their study which cut across cultures and species and compared annual war deaths for 11 chimpanzee communities, 24 hunter-gathering communities, and countries that fought in WWI and WWII, they found that  overall battle-deaths in modern organized societies is exponentially higher than in hunter-gatherer societies of the past 200 years. They also found that humans have evolved to be more violent than chimpanzees. Pincker disputes these findings.

Regrettably, we need look no further than the news to realize that violence still certainly persists. The newest country in our international system, South Sudan, gained independence in July 2011 after five decades of ethnic conflict and 2 million deaths. However, eventually there came troubling reports of renewed ethnic conflict. A mere three hundred yards from the UN compound in South Sudan, the corpses began. Hundreds, perhaps thousands, died in ethnic conflict between the Nuer and Murle tribes. Syria’s civil war continues with other regional and major powers fighting proxy war there. ISIS, essentially defeated in the Middle East, is morphing and continuing its violence in other regions of the world. We all watch the stand-off between North Korea and the United States with anxiety.

Picasso’s Guernica

What can you and I do? How can you and I “wage peace?” Let me offer several ways.

  1. Develop more empathy. Learn another person’s language but also learn about her/his history and culture. Try to put yourself in the other person’s shoes and see the world as that person sees it. If you already know another language, learn still another.
  2. Listen to each other more; respect each other more. Look for and build on our common interests. War is possible but so is peace. You may have seen the Hollywood movie “War Horse.” In the scene on the Western Front, British and German soldiers stop fighting for a few minutes to free the war horse from the barbed wire between the trench lines in No Man’s Land. A British and a German soldier jointly free him from the wire and flip a coin to see who will take the horse. In this case the life of this remarkable horse that had made it through the night in No Man’s land served to give the enemies a common purpose.
  3. Study and learn the essentials of Power and Influence in this world. Examine and learn about power and influence between individuals, groups, companies, states, and other international actors. Your goals for peace and stability probably cannot be achieved by kindness alone. Learn to operate in this world of power and influence while compromising your own principles as little as possible. To help you understand blunt, hard-nosed, Machiavellian power politics, watch the movie: “Elizabeth.”
  4. For peace to prevail, compromise among competing groups is necessary. In your group, distinguish the essential and vital from the not-so-essential. Be ready to compromise. To help you understand the negative consequences of the persistent striving to dominate and be Number 1, watch the movie: “A Beautiful Mind.”
  5. If we wish for a better world, you and I must strive to make the various episodes of life end well—with goodness and justice winning over malice and evil.
  6. Lastly, we must all enhance our inner capacities for peace and reconciliation. Challenge yourself to enhance the “better angels” of your nature.

As one of my heroes, Abe Lincoln, said famously in his first inaugural address: “I am loathe to close.  We are not enemies, but friends.  We must not be enemies… The mystic chords of memory, stretching from every battlefield, and patriot grave, to every living heart and hearthstone, all over this broad land, will yet swell the chorus of the Union, when again touched, as surely they will be, by the better angels of our nature.” (Please see Part II.)

(Note: See President John F. Kennedy’s “Peace Speech” in June 1963:


Brodie, Bernard. War and Politics. NY: MacMillan, 1975.

Claude, Inis L. Power and International Relations. NY: Random House, 1966.

von Clausewitz, Carl. On War. Translated and edited by Michael Howard
and Peter Paret. Princeton, NJ: Princeton University Press, 1976.

Kagan, Donald. On the Origins of War and the Preservation of Peace. NY:
Doubleday, 1995.

________ . The Peloponnesian War. NY: Viking, 2003.

Mearsheimer, John J. The Great Delusion: Liberal Dreams and International
Realities. New Haven: Yale University Press, 2018.

________ . The Tragedy of Great Power Politics. NY: W.W. Norton, 2001.

Morgenthau, Hans J. Politics Among Nations: The Struggle for Power and Peace.
NY: Alfred A. Knopf, 1973.

Stoessinger, John G. Why Nations Go to War. NY: St. Martin’s Press, 1974.

Sun Tzu. The Art of War. Translated by Samuel B. Griffith. London:
Oxford University Press, 1963.

Waltz, Kenneth N. Theory of International Politics. NY: Random House, 1979.

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