Last week, on the same day that McSweeney's Books published a new, paperback edition of my book The End of War, I argued that we must and can end war and militarism, our most urgent problems.

In a thoughtful response to my column, my fellow science writer Keith Kloor suggests that "at first blush," the quest to end war seems "quixotic and naïve." Kloor poses a couple of questions for me that others have posed too—and that I struggled with while researching and writing The End of War. In this post, I'll respond to Kloor's queries and see if I can make him a bit more optimistic.

Kloor quotes me saying: "Sometimes violence is morally justified, even necessary, to thwart greater violence. So the question is, how should we react to lethal group violence when it erupts in the world today?"

"But is that the right question?" Kloor asks. "I would think that the greater challenge is eliminating the main reasons why one group of people sets out to kill another group. All through history wars have been fought over land, religion, flag, and ethnicity, to cite just a few of the major triggers."

When I started researching war, I also assumed that to get rid of war, we have to get rid of its root causes. The trouble is, scholars have identified countless causes of war. One pseudo-explanation (which I'm glad Kloor does not mention, and which I rebut early on in my book and in posts such as this) is that war stems from a compulsion bred into our ancestors by natural selection. Biology underpins war, as it underpins all human behaviors. The crucial question is, why does war break out in certain places and times and not others?

The most popular non-biological explanations of war are what I call the Malthusian and Marxist hypotheses. The first posits that war stems from our tendency to over-reproduce and hence fight over land and other resources. The second holds that war stems from inequality, the tendency of societies (especially capitalist ones) to divide into haves and have-nots.

Scholars have also blamed wars on religion, racism and nationalism, which Kloor mentions above, as well as such fundamental social traits as hierarchy, sexism and injustice. If you cherry pick, you always find evidence to support your favorite theory.

But as scholars such as Lewis Fry Richardson (whom my friend David Berreby recently profiled) have shown, neither the Malthusian and Marxist theories nor any of the other explanations above can account for the vast diversity of wars. Moreover, some factors that provoke conflict, such as religion, can also inhibit it. Religion has inspired some of our greatest antiwar leaders, notably Gandhi and Martin Luther King.

I have found only one theory of war that fits the facts. The theory holds that war is a self-perpetuating, contagious meme, which can propagate independently of other social and environmental factors. As anthropologist Margaret Mead put it in a famous 1940 essay, "Warfare Is Only an Invention—Not a Biological Necessity."

In other words, the major cause of war is war itself, which has a terrible tendency to spread even to societies that would prefer to remain peaceful. I make this point in my book and in a 2010 blog post, "Margaret Mead’s war theory kicks butt of neo-Darwinian and Malthusian models." Here is an edited excerpt:

In his 1997 book War Before Civilization, anthropologist Lawrence Keeley notes that war among North American Indians often stemmed from the aggression of just a few extremely warlike tribes, "rotten apples that spoiled their regional barrels." He added, "Less aggressive societies, stimulated by more warlike groups in their vicinity, become more bellicose themselves."

Societies in a violent region, the political scientist Azar Gat emphasizes in his 2006 book War in Human Civilization, have a strong incentive to carry out preemptive attacks. Societies may "attack the other side in order to eliminate or severely weaken them as a potential enemy. Indeed, this option only makes the other side more insecure, rendering the security dilemma more acute. War can thus become a self-fulfilling prophecy. The fear of war breeds war."

Many people are pessimistic about ending war because they assume it will require radical social engineering. World peace will require eliminating poverty, inequality, sexism, racism or [fill in the blank]. We will need to eradicate religion, or all embrace the same religion. We will need to get rid of all nation states and become anarchists, or form a single global government.

My analysis of war suggests that if we want to end war, we don't need to create a society radically different from our own, let alone a utopia. If we want to end war, we should focus on ending war and the culture of war rather than on supposed causal factors. If we can do that, we will take a major step toward solving many of our other social problems, as I argued in my previous post.

And that brings me to Keith Kloor's final challenge to me. He devotes much of his column to a discussion of how extremists on both sides of the conflict between Israel and Palestine have "hijacked the peace process. Horrific spasmodic cycles of violence and death is the result." He asks me how we can "rid the world of extremist groups that sow the seeds of war."

Kloor has his causation backwards. Just as war promotes poverty, tyranny, inequality and resource depletion at least as much as vice versa, so war promotes fanaticism. Once militarism seizes hold of a society, it can transform vast populations into virtual sociopaths. It turns decent, ethical, reasonable people into intolerant fanatics capable of the most heinous acts.

Breaking out of what Kloor calls "spasmodic cycles of violence and death" can be extraordinarily difficult, but history offers many examples of societies that have done just that. Germany and France were bitter, bloody rivals for centuries. But it is now inconceivable that Germany and France—or any members of the European Union--would go to war against each other.

One of my favorite examples of a nation that has renounced militarism is Costa Rica. Like many of its neighbors in Central American, Costa was once wracked by terrible violence. But after a bloody civil war in the 1940s, Costa Rica disbanded its army, freeing up more funds for education, health care, transportation and tourism. It is often ranked as one of the most peaceful, healthy, "happy" nations in the world.

Transcending a lethal stalemate often, although not always, requires courageous, imaginative leadership, such as that shown by Menachem Begin and Anwar Sadat when they agreed to a peace treaty between Israel and Egypt in the late 1970s, or by Nelson Mandela and F.W. de Clerk when they negotiated the end of apartheid in South Africa in the early 1990s.

One way to promote peace is to point out to groups with grievances that nonviolence usually produces better outcomes than violence. This is the theme of the work of political scientist Gene Sharp, which I discuss at length in The End of War.

But to my mind, the U.S. remains the key to fostering peace today, both in the Mideast and worldwide. The U.S. preaches peace to the Israelis and Palestinians, just as it preaches to the Russians, Ukrainians, Iranians, North Koreans and other people around the world. But the preaching of the U.S. rings hollow.

To adopt Kloor's language, the U.S.--more than any other nation or group--sows "the seeds of war" around the world through its militaristic behavior. Just look at the "cycles of violence and death" we have triggered in Iraq and Afghanistan, which have become breeding grounds for ISIS and other violent groups. The U.S. has the potential to become a moral exemplar and lead the world to peace. But if we want to rid the world of lethal extremism, we should start with ourselves.

Image:, Wikimedia Commons