CHRISTOPHER A. PREBLE: An abhorrence of war flows from the classical liberal tradition. Adam Smith taught that “peace, easy taxes and a tolerable administration of justice” were the essential ingredients of good government. War, on the other hand, is the largest and most far-reaching of all statist enterprises. It’s an engine of collectivization that undermines private enterprise, raises taxes, destroys wealth, and subjects all aspects of the economy to regimentation and central planning.

It also subtly alters the citizens’ view of the state. “War substitutes a herd mentality and blind obedience for the normal propensity to question authority and to demand good and proper reasons for government actions,” the late scholar Ronald Hamowy writes in The Encyclopedia of Libertarianism. He continues, “War promotes collectivism at the expense of individualism, force at the expense of reason and coarseness at the expense of sensibility. Libertarians regard all of those tendencies with sorrow.”

Nobel Laureate Milton Friedman stated the issue more succinctly. “War is a friend of the state,” he told the San Francisco Chronicle about a year before his death. “In time of war, government will take powers and do things that it would not ordinarily do.” The evidence is irrefutable. Throughout human history, government has grown during wartime, rarely surrendering its new powers when the guns fall silent.

Some might claim that a particular threat to freedom from abroad is greater than anything we could do to ourselves in fighting it. But that is a hard case to make. Even the post‑9/​11 “global war on terror” — a war that hasn’t involved conscription or massive new taxes — has resulted in wholesale violations of basic civil rights and an erosion of the rule of law. From Bush’s torture memos to Obama’s secret kill list, this has all been done in the name of fighting a menace — Islamist terrorism — that has killed fewer American civilians in the last decade than allergic reactions to peanuts. It seems James Madison was right. It was, he wrote, “a universal truth that the loss of liberty at home is to be charged to the provisions against danger, real or pretended, from abroad.”

But surely, some say, the United States is an exceptional nation that serves the cause of global liberty. The United States pursues a “foreign policy that makes the world a better place,” explains Sen. Lindsey Graham, “and sometimes that requires force, a lot of times it requires the threat of force.” By engaging in frequent wars, even when U.S. security isn’t directly threatened, the United States acts as the world’s much-needed policeman. That’s the theory, anyway.

In practice, the record is decidedly mixed. This supposedly liberal order does not work as well as its advocates claim. The world still has its share of conflicts, despite a U.S. global military presence explicitly oriented around stopping wars before they start. The U.S. Navy supposedly keeps the seas open for global commerce, but it’s not obvious who would benefit from closing them — aside from terrorists or pirates who couldn’t if they tried. Advocates of the status quo claim that it would be much worse if the United States adopted a more restrained grand strategy, but they fail to accurately account for the costs of this global posture, and they exaggerate the benefits. And, of course, there is the obvious case of the Iraq War, a disaster that was part and parcel of this misguided strategy of global primacy. It was launched on the promise of delivering freedom to the Iraqi people and then to the entire Middle East. It has had, if anything, the opposite effect.

Libertarians should immediately understand why. We harbor deep and abiding doubts about government’s capacity for effecting particular ends, no matter how well intentioned. These concerns are magnified, not set aside, when the government project involves violence in foreign lands.

In domestic policy, libertarians tend to believe in a minimal state endowed with enumerated powers, dedicated to protecting the security and liberty of its citizens but otherwise inclined to leave them alone. The same principles should apply when we turn our attention abroad. Citizens should be free to buy and sell goods and services, study and travel, and otherwise interact with peoples from other lands and places, unencumbered by the intrusions of government.

But peaceful, non-coercive foreign engagement should not be confused with its violent cousin: war. American libertarians have traditionally opposed wars and warfare, even those ostensibly focused on achieving liberal ends. And for good reason. All wars involve killing people and destroying property. Most entail massive encroachments on civil liberties, from warrantless surveillance to conscription. They all impede the free movement of goods, capital, and labor essential to economic prosperity. And all wars contribute to the growth of the state.

JIM ANTLE: I want to focus on the politics of what makes it difficult for there to be a libertarian foreign policy. There are a lot of political and structural impediments to the government doing less of anything. And there’s a strong bias among the American people that when you face some economic or social problem — from healthcare to education to welfare — the government should do something. When you say the government should do less or limit its response, many are skeptical.

When it comes to foreign crises, you’re constantly faced with bad actors on the international stage — from dictators to ayatollahs. The argument that we should restrict intervention or avoid projecting strength often doesn’t resonate. What’s interesting, however, is that you generally don’t get both of these attitudes — government activism at home and abroad — from the same person. Those most likely to grasp that government is not the solution to every domestic problem are the most likely to be skeptical of that argument when it’s presented in foreign policy. And that really means that those advocating a libertarian foreign policy are men and women without a country. In our binary political system, there’s no party or constituency that’s really speaking for that viewpoint.

You can see the evidence of that in the congressional vote for the Iraq War. Among Republicans, there were only seven who voted against authorization. What’s less well remembered is that half the Democrats in the Senate voted to authorize the Iraq War. The list includes Hillary Clinton, Joe Biden, John Kerry, Chuck Schumer, and Harry Reid. These are not “back-bencher” Democrats. They’re some of the most prominent figures, including the supposed Peace Party’s most likely next candidate for president of the United States.

That means that the parties really present an echo, not a choice. There’s this “me tooism,” even when it comes to Democrats. In some respects, that makes sense because they’re the party that believes in the government’s ability to keep us safe all of the time and in every situation. But some of it is also a relic of politics from the 1980s and 1990s, when a lot of these people came of age at a time when the Democratic Party was seen as weak on foreign policy. A lot of Democrats internalized that critique and regarded it as a political liability. Ultimately, they tried to counter that liability by becoming more hawkish.

The odd thing about that is that it doesn’t reflect many of the trends in public opinion, particularly those of rank-and-file Democrats. But politicians tend to stick with the ideas they adopted during their formative years. So you have a generation of hawkish Democrats leading a party of people who are hesitant to see such an outsized U.S. role in the world, and particularly in the Middle East. Thus a lot of the core assumptions that are being batted around by both parties in discussing the potential nuclear threat from Iran are very similar to the core assumptions that led us into the Iraq War.

So what do we do about this? There was a period when we were seeing real growth in the libertarian wing of the Republican Party, and some chastened conservatives seemed to be moving in that direction. But, again, it’s easier to make those arguments when everything is going well. As soon as there’s any significant instability in the world, it becomes much harder to make non-interventionist arguments in foreign policy. The Republican Party seems at the moment to be reverting to form.

But I don’t think all is necessarily lost. True, the political incentives for even the best-intentioned libertarian-leaning Republicans are bad. They will be punished by the loudest voices on the right if they say anything that deviates from the idea of aggressively projecting strength. At the same time, there’s been a lot of success framing a libertarian non-interventionism as President Barack Obama’s foreign policy. Now I find it interesting that a president who escalated one war, launched two more without congressional approval, and proposed a fourth is any kind of non-interventionist. But there you have it. Our binary political system makes it difficult to have these debates in a nuanced fashion.

On the positive side, I’ve always argued that we need to get people who are engaged in economics — those conservatives and libertarians who specialize in fiscal areas — to be a little more vocal on foreign policy. In private, you often hear a lot of conservative budget experts express their doubts about an ever-expansive military footprint abroad. There of course still needs to be some foreign policy expertise that comes from a less interventionist perspective on the right.

But, in the meantime, as we cultivate those voices, there’s a vacuum that needs to be filled by people who are philosophically sympathetic to less intervention and yet specialize in other issues. They shouldn’t let the wall of separation between budget gurus and defense hawks dictate what the Republican Party’s foreign policy is going to be.

JUSTIN LOGAN: I want to start off by asking: What do people want from foreign policy? And I want to first consider whether or not the foreign policy judgments of libertarians, conservatives, and liberals flow from their respective political philosophies.

In a basic sense, what we want from foreign policy is the efficient production of national security. We want to make sure that Americans are safe, that our sovereignty is protected, and that we have the ability to live our lives without coercion from some external threat. Simply put, if someone has a good way of achieving these ends, everyone should support it — libertarians, liberals, conservatives, whomever. Thus, the first-order considerations about foreign policy turn on questions about how dangerous the world is and how to effectively interact with it.

In terms of what libertarian foreign policy scholars believe, on those first-order considerations, most think that the United States is the most secure great power in modern history. We’re not in Shangri-La or the Garden of Eden, but we’re pretty close. Libertarians also think that if the United States defended fewer countries on their behalf, they would defend themselves to a greater extent than they do now.

In a recent academic article, it’s mentioned that the United States has formal treaty commitments to countries comprising 75 percent of the world’s gross domestic product. That is a striking figure. To what extent has Uncle Sam become Uncle Sucker? The U.S. government is paying for other people’s defense, forcibly taking money from taxpayers in order to spend it on other countries. To be more provocative, I think the greatest threat to U.S. national security in recent decades has been the ideas that have sprung from the minds of the American foreign policy elite — not al Qaeda, not Iran, not China, not Russia. Rather, the wreckage that the American foreign policy elite has produced in carnage and in trillions of dollars squandered has been most damaging to Americans’ well-being.

But it’s on second-order considerations where I think we can draw a straight line from libertarian principles to opposition to ambitious foreign policies. For instance, war makes the government bigger. War is very damaging to civil liberties. War costs lots of money, damages lives, and leads to corruption. But unless you’re a pacifist, those second-order considerations really are subordinate. If we could never do anything to violate civil liberties, or if we could never do anything to get our fellow citizens killed in large numbers, if we could never do anything that spent lots of money on overseas adventures, then we would never have any security commitments. If the cost of protecting civil liberties were an ISIS amphibious landing in Miami, many libertarians would support abrogating civil liberties. So what we’re trying to figure out is when a libertarian would support damaging liberty and favor intervention. But that goes back to those first-order considerations about the nature of the world in which we live, how states relate to one another, and how secure the United States is.

A belief in the value of a system of government that embraces individual liberty doesn’t necessarily tell you how much to worry about China. All political philosophies need help in thinking about how to craft foreign policy.

To recapitulate, what’s libertarian about our foreign policy is a concern for those second- order implications. As to the first-order judgments about how dangerous the world really is, a political theory that prioritizes liberty is only so much help. Only in extreme circumstances — one example being the Iraq War — could we say that a foreign policy is blindingly anti-libertarian.

So what do libertarians (or conservatives or liberals) need to bring to the table in order to think about these first-order considerations? They need theories of international politics and foreign policy. They need an understanding of how states relate to one another, what causes conflicts, and how to judge those threats. With some exceptions, libertarian foreign policy scholars embrace a school of thought called realism. Realism is a pessimistic view of the world. It holds that states jealously compete with one another for power and position. It’s skeptical about how states use and in many cases abuse power against one another.

There’s also an emphasis on balancing power in realism. If you think about the debate around the separation of powers during the Founding period, it wasn’t so much that the Framers thought that any particular president or any particular legislature or any particular judiciary was going to be wicked and venal. They thought that concentrated power itself was dangerous, and the only way to ensure that people would be free from the rapacious use of that power was to check it with countervailing powers. This notion permeates the theory of realism.

The political scientist Hans Morgenthau, for instance, approvingly cites John Randolph’s statement that “you may cover whole skins of parchment with limitations, but power alone can limit power.” This is one element of how most libertarian and realist foreign policy scholars think about international politics.