When Americans talk about foreign policy, we don't talk about much.

To be sure, we have plenty to discuss: Limiting our conversation to the past two decades alone, we might address the ongoing wars in Afghanistan, Iraq, Somalia, Syria, and Yemen; plus additional military intervention in Pakistan, Libya, Niger, and a whole host of other African countries; as well as permanent military bases abroad in South Korea, Japan, Europe, and beyond. We might discuss our rivalries with Russia and China or our enmity with Iran, North Korea, Venezuela, and Cuba. Or we might talk about our extensive sanctions regime and its consequences for innocent people.

We should and (sometimes) do talk about all that. But what we don't talk about is the debate itself — about why we think some risks and costs are justified and others aren't, or why, exactly, it would be unthinkable to act on President Trump's recent suggestion that "kill[ing] 10 million people" is the fastest route to victory in Afghanistan. For though its topics are many, our foreign policy debate's boundaries are close and its concerns are few. Our conversation is narrow in the extreme.

I think about that narrowness a lot, because I'm always bumping into it. I write on foreign affairs regularly, both here at The Week and for Defense Priorities, a policy shop where I'm a fellow. As you'll gather if you click some of those links, I'm a harsh critic of our foreign policy as it has functioned under the administrations of Presidents George W. Bush, Barack Obama, and now Donald Trump. What you might not get from many of those links, however, is why.

The arguments against the United States' aggressive, interventionist foreign policy which matter to me most are humanitarian. But that's rarely the case I make. See, for example, this piece from April on Trump's veto of a bill to end U.S. backing of Saudi Arabia's war in Yemen. About two thirds of the way through I get to constitutional, practical, and strategic arguments, and though I do think those are important and correct, they aren't what I find most compelling. They aren't what had me writing in a mad fury that this moral horror will continue with American support. But they are where the great bulk of our national debate is located.

That location is the tradition known as just war theory. You may not know the name, but if you are American (or European), there is a strong chance your thinking about matters of war and peace operates within that paradigm. Just war theory has its origins in Christian theology, but it has spread far beyond any religious association to inform national and international law and frame the foreign policy conversations of the Western world.

The basic assumption of the theory is that though war is an evil, it's sometimes the best option available to us. Our task, then, is deciding when war is therefore justified. We make this determination using two sets of questions.

The first — jus ad bellum, Latin for "right to war" — covers when we can enter conflict. Here we ask things like: Are we attacking or defending? Has a legitimate authority authorized us to fight? Is war a proportionate response to whatever offense we suffered? Have we exhausted all other possible responses? Going back to that Yemen piece, my discussion of how the Constitution assigns war powers to Congress, not the president, is a classic jus ad bellum argument. The just war framework says part of what made it illegitimate to help Saudi Arabia bomb a school bus full of children is that the bombing wasn't greenlit by a legitimate authority.

The second set of questions just war theory asks — jus in bello, "right in war" — is about how we conduct a war once it's started. These are questions like: Is our use of violence proportionate? Will we promptly accept our enemy's surrender to avoid unnecessary bloodshed? How do we treat prisoners of war? Are we avoiding civilian casualties when possible? Is the cost in blood and treasure worth what it's buying us? Are we on the lookout for unintended consequences of our actions? My argument in the Yemen article that the U.S. intervention is disproportionate to the realistic threat posed to Americans is a typical jus in bello claim. In this paradigm, the limited damage Yemen's Houthi rebels can realistically do us doesn't justify their country's mass starvation.

The thing I like about just war theory is that, if strictly applied, it's a rigorous standard. In fact, if strictly applied, I think it would require the United States to end all her present military interventions immediately and pursue a dramatically more restrained foreign policy. In practice, however, just war theory is almost never used that way. Its questions, intended to avert foolish and unethical war-making, are more often massaged into justifying exactly that. This is a big part of why I reject just war theory — and yet you will often find me writing within its framework, because it's the only framework our national conversation really allows.

The range of acceptable vocabulary and argumentation in U.S. foreign policy — "acceptable" as in it stands a chance of being published by reputable outlets and taken seriously by people with any degree of influence over policy development — is very small and basically contained within the just war tradition. So when I'm writing about foreign affairs, if I want to do more than preach to the anti-war choir, I have to speak that language.

I have to talk about national interest, grand strategy, deficit spending, congressional authorization, burden sharing. These are all important things to consider, absolutely, and I think they militate against our foreign policy as it stands. I am not making arguments I don't believe, but I am making — and feel I am required to make if I want my work to wield any significant influence — arguments that matter much less to me than the straightforward moral case.

In a conversation where even modest arguments for restraint must fend off accusations of isolationism and naivete, no one takes seriously a stringently humanitarian approach. And that's to say nothing of my Christian commitment to nonviolence, which would be laughed right out of the room. (Remember when Ron Paul tried to bring the Golden Rule into foreign policy back in 2012? He was booed.) If I want to introduce that theological conviction to the foreign policy conversation (and, to be clear, I don't expect the state to renounce violence), it isn't enough to translate it for public consumption in a pluralist society, which is a reasonable obligation. I also have to link it, as in a weird game of Jeopardy!, to a question just war theory asks.

You may share some or all of my ideas about war and peace and wish that I would do less of this repackaging in an effort to expand the tiny Overton Window. I agree that's a worthwhile aim and sometimes write accordingly, as in the first part of my article on Yemen. The reason I don't write that way all the time is I recognize the reality of the window, and I consider ending these wars a more pressing concern than improving how we talk about them, as important as that is. If a just war argument could help end our contribution to the tragedy in Yemen, for example, I will make that argument until I'm blue in the face.

If you don't share any of my ideas about war and peace — if you think I'm an isolationist and naïve about American security — I would encourage you to still consider it worthwhile to hear me and others who substantially vary from the foreign policy consensus speaking our own language. It would help dismantle strategic and ideological stagnation and make space for Washington to learn from its mistakes. Whatever you think a better foreign policy would look like, the narrowness of our conversation makes it more difficult to improve. Our boundaries of debate do no one any good.