By Stephen M. Walt

Stephen M. Walt is a columnist at Foreign Policy and the Robert and Renée Belfer professor of international relations at Harvard University.

It’s the holiday season in much of the world, when thoughts typically turn to visions of a better world. Hymns praising peace will be sung in churches, pious sentiments will ring out from pulpits, and religious and secular leaders alike will mark the new year with expressions of hope for the future. Such sentiments will sound hollow, however, if we reflect on the brutal carnage in Gaza, the relentless destruction in Ukraine, the senseless civil war in Sudan, and all the other bloodlettings that are underway around the world. Not to mention the vast resources that countries continue to spend finding more and better ways to kill other human beings.

Can we do anything about this? A few weeks ago, I attended a fascinating seminar on space exploration, and the topic of manned versus unmanned activities came up in the discussion. The speaker observed that sending human beings into orbit, to the moon, and someday to Mars might be worth doing because humans need new and difficult challenges to inspire them.

His comment got me thinking. I believe unmanned space exploration makes more sense than sending people into orbit or to the moon—for reasons my late father laid out here—but maybe we do need lofty and possibly unreachable goals in order to reach new heights of achievement. If so, why not strive for something equally miraculous but a little closer to home? Instead of humans on Mars, why not peace on Earth?

I’m aware of all the obstacles standing in the way of this utopian vision. In a world with no central authority, states will worry about security and take steps to protect themselves, and their efforts to do so will often threaten others and sometimes lead to violence. Uncertainty, ignorance, and various forms of cognitive bias can lead countries to blunder into wars that could and should have been avoided. Some leaders will launch wars to preserve their own power or to leave their mark on history. Nations with long-standing grievances sometimes use force to try to reverse them, and interest groups of various sorts may push for war to enhance their influence, pad their own profits, or advance some special cause of their own. Ideologues convinced that they have discovered the One True Way for societies to be governed will sometimes launch ambitious crusades to impose their beliefs on others.

War’s persistence across the millennia calls for humility, even as we grope for solutions. There’s no magic wand that can end the scourge of war, but here are a few modest ideas for building a (somewhat) more peaceful world.

First, world leaders (and publics) could start by taking realism’s lessons more seriously and cast a more skeptical eye on any ideology that claims to have found the key to ending war forever. Marxists thought overthrowing capitalism would remove incentives for war and usher us into a tranquil socialist paradise. Liberals think spreading democracy will accomplish the same miracle, even if they don’t know how to export democracy and even if it requires us to first fight “wars to end war.” Libertarians want to shrink the state; fascists tell us to worship the state; and anarchists want to destroy the state completely—and each group is convinced that all will be well if we just follow their advice. Some believers think peace will emerge once everyone worships the right god, and some atheists maintain we would have a more peaceful world if we stopped worshiping any gods. Because these proposals all require imposing political beliefs on others who may not want to accept them, they typically make the problem worse rather than better.

By contrast, realism encourages humility. It highlights human fallibility, the dangers of unchecked power, the limits of reason, and the ease with which the strong and privileged become arrogant and overconfident. It recognizes the unavoidable uncertainty that plagues political life and the tragic elements that are an inescapable part of human existence. Political realism depicts a world that is rarely black or white but typically contains many shades of gray, a world where unintended consequences abound and success today plants the seed for tomorrow’s troubles.

For this reason, most realists believe states should go to war only under direst necessity, i.e., when their own survival and/or vital interests are at stake. In recent decades, at least, a foreign policy based on realism and restraint would almost certainly have made peace more prevalent.

Realism also suggests that appeals to our common humanity will not bring the world closer to peace. Humans are social animals with a deeply engrained tendency to divide into groups and to cast a wary eye at those who are seen as different. When push comes to shove, most social groups put their own interests first, even if this requires harming others. Grassroots peace movements and other antiwar activities will not suffice, either, because even in democracies, decisions for war are made by a handful of people at the top. For this reason alone, one can only encourage peace by convincing leaders (and their followers) that going to war will not make their positions more secure and will not make their countries safer or richer.

It follows that a more realistic approach to peace would take balance-of-power politics to heart. By that I mean remembering that states in anarchy invariably worry when others grow too strong, and they will try to redress the balance to preserve their own security. For this reason, relentless efforts to enhance one’s power at the expense of others are usually self-defeating, because other states will eventually join forces to check a powerful state and contain its ambitions.

A corollary to this principle is that threatening a great power’s vital interests—and especially near its home territory—is bound to provoke a harsh reaction. If more leaders appreciated these tendencies, then ill-considered attempts to gain enduring advantages would occur less often. Moreover, leaders who developed a keen sense of empathy—i.e., the ability to see things from another side’s perspective without necessarily agreeing with it—would be less likely to cross red lines by mistake, better equipped to find solutions that would leave all parties better off, and less likely to stumble into foolish wars of choice.

Second, although most political leaders gain and retain power by appealing to their fellow citizens’ sense of national pride, they often forget that similar forces exist in other countries, too. Russian President Vladimir Putin erred by discounting the power of Ukrainian nationalism and found himself in a war that has proved to be far more costly than he expected, whatever the ultimate outcome. The power of nationalism also explains why powerful countries cannot bomb others into permanent submission, and why weak and vulnerable states resist sanctions and other forms of coercion even when doing so is extremely costly. If more leaders appreciated this aspect of world politics, fruitless efforts to compel, weaken, or destroy others would be less common.

Third, leaders contemplating war should be reminded that once the fighting starts, they are no longer in control of their fate. Going to war unleashes a vast array of complicated and unpredictable elements that cause most wars to last longer, and cost more, than their initiators expect. British Prime Minister Winston Churchill was hardly a pacifist, but he did grasp this enduring feature of world politics. As he wrote in My Early Life, “The statesman who yields to war fever must realize that once the signal is given, he is no longer the master of policy but the slave of unforeseeable and uncontrollable events.” George W. Bush kept a bust of Churchill in the Oval Office while he was president, but I doubt he ever read that little kernel of wisdom. If he had, he might have thought harder before invading Iraq in 2003.

And while I’m on the subject of Churchill, the frontispiece to his multivolume history of World War II reads, “In War, Resolution; in Defeat, Defiance; in Victory, Magnanimity; in Peace, Good Will.” That’s not a bad catechism, and I call your attention to the last two phrases. Imposing a one-sided victor’s peace is a recipe for more trouble down the road, especially when one’s former opponents are likely to recover from their defeat. The United States didn’t help rebuild Germany and Japan after World War II out of a sense of philanthropy, but neither did it impose the Carthaginian peace that some officials advocated. The contrast with the punitive Treaty of Versailles that ended World War I could not be more striking. Similarly, treating Russia like a defeated power and paying scant attention to its legitimate fears for years afterward poisoned relations and helped pave the way to today’s troubles, as a number of prescient observers repeatedly warned.

Fourth, because war is always costly and unpredictable, wise leaders will exhaust every alternative before rolling the iron dice. No one knows if there was a diplomatic bargain to be had that might have forestalled Russia’s invasion of Ukraine, or if the mediation efforts that were underway in March 2022 might have ended the war quickly and saved Ukraine from dismemberment and vast destruction. But there is now a growing body of evidence showing that Western leaders—and especially top officials in the West—did not pursue alternative solutions as thoroughly as they should have. Such efforts might have failed, but a more serious effort to forestall the war, or to nip it in the bud, would have been preferable to the war that occurred.

Lastly, efforts to promote peace might be furthered if we asked aspiring leaders to explain what they intend to do to make peace more prevalent and robust. Those who aspire to lead a country usually have lots to say about how they will make it stronger, but the real question we should be asking them is how they are going to make their fellow citizens safer. Seriously, shouldn’t anyone who wants to be a president or prime minister have to explain what they are going to do to make war less likely and peace more robust? If they answer by saying the problem is everyone else’s fault and that peace will only be possible once the troublemakers are destroyed, then we’d know that this is someone who is not really interested in peace. If all they can utter are simplistic cliches (“peace through strength,” “remember Munich,” etc.), we should look for candidates with a more sophisticated understanding of how world politics really works. If the importance of peace has never occurred to them and they have nothing to say, reporters should ask them why this is the case. And if any of them try to tell us that war is a great and glorious activity that we should welcome, or insist that potential foes are paper tigers who will be easy to defeat, stock up your pantry or head for your local bomb shelter.

As I hope I’ve made clear, there are no easy solutions to the problem of war. But if humans really do need a new challenge, a sustained but realistic effort to reduce war’s likelihood and destructiveness would benefit humanity far more than sending a few brave humans to some distant celestial orb. And the place to start is by constantly reminding leaders that starting a war rarely produces the desired results and often leads to unexpected and very nasty surprises.

Perhaps that lesson would help them do better in 2024 than they did last year. I’ve set the bar low; let’s hope they can clear it.

Note: This article was originally published by Foreign Policy at https://foreignpolicy.com/2023/12/19/realist-guide-world-peace/.