What is the point of U.S. immigration law?

That might seem like a stupidly simple question. But the Trump administration is now shattering families at the border and placing terrified children in kennels in the name of enforcing that law.

This was a choice by the White House to use maximal cruelty as a way to deter immigration. But to give more sober conservatives their due, it might also mark the beginning of the end for an American immigration system that has been plagued by self-contradictions and reversals. Trump's cruelty is a difference of degree rather than kind from previous administrations.

Which gets us back to the question of what exactly we're trying to achieve here.

You often hear that we must crack down on illegal immigration because lawbreaking should not be tolerated. But that's entirely circular. We get to decide the content of immigration law, and thus what sort of immigration is or isn't lawbreaking. From Prohibition to the modern war on pot, there are plenty of examples of laws that caused far more damage than they prevented. It's at least possible that immigration law falls into the same category.

There's also a popular refrain from Trump and other conservatives that "if you don't have a border, you don't have a country," as the Washington Examiner put it. I've never understood what this means. Let's say we just granted legal residency to everyone the second their feet hit U.S. soil. That would still be an immigration policy. The border would still be there. It would still demarcate the realm where the U.S. Constitution and American governance applies. U.S. citizens would still have privileges residents wouldn't. None of that would change.

Once you clear out the clutter, there are usually two remaining justifications for tightly controlling immigration into the country: Too much immigration or the wrong sort can harm jobs and wages for people already here. And immigration can strain social cohesion, leading to a more alienated and distrustful society. (There's also, of course, Trump's own racist insinuation that immigrants bring crime and drugs and so forth, nevermind the clear data that they actually commit less crime than the native born population.)

Let's take these two in order.

Many Americans fear that new immigrants will compete with workers who are already here, driving down job opportunities and wages for everyone. (Even Bernie Sanders called open borders a "Koch brothers proposal.") It's certainly possible, but actual evidence of this effect is hard to come by because economists have few natural experiments to test the theory. So they wind up statistically slicing and dicing rare events like the Mariel boat lift beyond all recognition, trying to draw sweeping national conclusions from how wages or jobs changed for tiny numbers of people.

More to the point, even if the problem is real, we know how to fix it: Make sure the jobs supply always outpaces the combined labor supply of U.S. citizens and immigrants. It's hard to overstate all the ways American economic policymaking already grossly fails to generate enough jobs — and how many options we have for fixing the problem that don't involve brutalizing people just trying to improve their families' lives.

To take a dramatic example: Some Democrats are advocating for a national job guarantee. If we passed that and allowed all immigrants to participate, it would solve the whole problem at a stroke. We'd set a floor under everyone's compensation, and make sure the supply of workers never outpaced the supply of jobs. But there are plenty of other options we could try too, from reforming monetary policy to expanding public investment to strengthening the welfare state and other stimulative fiscal policies.

Critics might respond that this scenario would absolutely flood the country with immigrants. But just physically getting to America is an expensive and arduous process, especially for the poorest immigrants who need these jobs the most. Plenty of people don't want to leave their homes and communities and families even if a better job offer is on the table. We're also a vast and wealthy country, able to absorb far more people than we do now if we'd just redirect our economy away from its focus on further enriching the 1 percent.

That leaves the idea that immigration threatens community stability. A lot of this comes from a decade-old study by Robert Putnam that found increased diversity in neighborhoods correlates with lower social trust. But studies since have complicated Putnam's data, and other studies have contradicted his findings entirely.

More importantly, if immigration does harm social trust, it's once again not hard to understand how — or how to fix it. America has become a vertiginously unequal society, with stagnating wages and a huge underclass forced into subpar jobs. If more recent immigrants aren't assimilating at the same rates (as measured by economic status or education) it's because they're arriving to a country that's far more stratified than it used to be. Often being non-white and poor, they're being pushed to the very bottom of that hierarchy. If they become angry and alienated from their adoptive home, well, who wouldn't?

Immigration law also inflames this. Undocumented immigrants know they could be caught and deported, so they stick to their own communities and languages and keep their heads down. They accept low wages under the table, which depresses everyone else's pay even further. These are the behaviors that immigration hawks point to when justifying crackdowns, but they're also how any sane person would respond to the threat of a crackdown.

I don't want to imply that fixing all this would be easy, or that the only answer is completely open borders. But the problems we associate with immigration are not inherent to immigration. They exist independently of it and are merely inflamed, at worst, when migration levels spike. Thus far we've tried clamping down on the immigration side of the equation, but that hasn't worked. And as Trump is ably demonstrating, the effort is turning us into monsters.

Perhaps it's time to focus on the other side of the problem.