Although many citizens in the developed world rarely question whether their national borders can be justified, the situation is the opposite in immigration scholarship—in which borders are seen as (at the least) a source of difficult ethical problems, if they are justifiable in the first place. Skepticism about border control is sometimes cited as the classic example of an idea that is popular among experts and unpopular with most other people. For that reason, it’s intriguing that there have recently appeared not one, but two sweeping arguments for open borders in Vox and the Atlantic.

The two arguments are strikingly similar. Vox made its case in late July, after Bernie Sanders criticized the idea of open borders as “a Koch brothers proposal.” In response, Dylan Matthews cited research pointing to the economic benefits of increased immigrations—not only for migrants who move from poor countries to wealthy ones, but even for workers in receiving countries. “The humanitarian gains of letting everyone who wants to make that leap do so,” Matthews wrote, “would be astounding.”

George Mason economist Alex Tabarrok’s new piece in the Atlantic, excerpted from a forthcoming book, echoes these points. “When a worker from a poorer country moves to a richer one, her wages might double, triple, or rise even tenfold,” Tabarrok writes. “Immigration is the greatest anti-poverty program ever devised.” “What moral theory,” he asks, “justifies using wire, wall, and weapon to prevent people from moving to opportunity?”

The recent prominence of migration in the news surely accounts for some of the polarities in related policy debates. This is the summer of a refugee crisis in Europe and Trumpism in the United States. These are high-stakes issues that generate powerful humanitarian urges among some and great fear of dislocation and disruption among others—which may help explain why the conversation is polarizing around giant new walls and open borders. I don’t mean to suggest that fearful nativism has either the empirical basis or the moral force of open borders advocacy, but it’s hard not to be struck by the sharp contours of the debate.

Still, clarification would be helpful. It may be true, for one thing, that increased migration is a powerful weapon against global poverty, but there’s a difference between saying that wealthy countries are obligated on that basis to allow more immigration and saying that they should have open borders. In fact, even an answer on that point requires addressing a still-more important question: What are “open borders,” anyway? Recent scholarship has argued that border openness is a matter of degree, and that it occurs along a variety of dimensions: how easy it is to enter a society, how easy it is to participate in it, and how easy it is to become a member. This means that any argument for or against open borders has to specify not only what should happen to would-be entrants when they arrive at territorial boundaries, but also how long they are permitted to stay; whether there are any qualifications (however minimal) for entry; and what social services, rights, and obligations they assume after entering (and when). It’s not clear that all of the foregoing issues are of the same ethical consequence, or that the humanitarian duties highlighted in these two pieces generate obvious answers to all of them. Yet if the world’s border guards suddenly vanished tomorrow, these questions would still remain.

That these basic questions would be left unresolved is a sign that arguments about the border need to consider issues beyond welfare. Vox’s piece devoted considerable space to debunking Sanders’s empirical claim that open borders would depress Americans’ wages, and it challenged his normative argument about privileging the interests of co-nationals. Still, while taking note of his insistence that open borders are a “Koch brothers proposal,” the piece did not discuss what he said next: “That’s a right wing proposal which says, essentially, there is no United States.” Similarly, the Atlantic piece makes oblique reference to a seminal article by claiming that “no standard moral framework, be it utilitarian, libertarian, egalitarian, Rawlsian, Christian, or any other well-developed perspective,” can justify closing borders to those who would like to enter. It then continues: “Nationalism, of course, discounts the rights, interests, and moral value of ‘the Other,’ but this disposition is inconsistent with our fundamental moral teachings and beliefs.” Condensing the familiar “to be sure” paragraph to one sentence, the article swiftly dispenses with potential objections.

Yet if the reference to “moral frameworks” reflects admirable engagement with the academic debate over this issue, the abrupt dismissal of nationalism unhelpfully sidesteps it. Nobody doubts that there are violent, dangerous forms of nationalism, and flatly “discounting” other people obviously runs contrary to all of our well-developed ethical theories. But even a brief engagement with the scholarly debate over open borders—a debate which informs both of these articles—reveals widespread skepticism that nation-states can be done away with so easily. Whether boundaries of some sort are a prerequisite of democracy and distributive justice is a hotly debated question, and approaches grounded in some reference to nationalism are not uncommon. As soon as we confront questions of distribution—what are we distributing, and how much of it, and to whom, and for what purpose, and on what basis—we must describe the scope of the community in question, and what unites it such that it should distribute these particular goods in this particular way. Rather than a hoary mysticism that encourages belligerence against imagined others, nationhood has been reformulated by many thinkers as one way of grounding answers to this basic question of democracy and distributive justice. There are important objections to this approach—but the assumption that nationhood amounts to little more than wall-fetishizing Trumpism leaves too many issues unaddressed.