Sometimes you’ll hear people who are generally free market friendly make statements like the following: “I support open borders in principle, but we can’t have both free immigration and a redistributive state so I reject open borders in practice.” The idea, roughly, is that while the standard arguments in support of free markets also support free immigration all else being equal, all else isn’t equal: closing our borders is justified as a means of preventing an overconsumption of state-provided benefits.
It’s worth mentioning that I think we should implement a redistributive program like a negative income tax or a universal basic income if it turns out to be the best institutional means of alleviating poverty. And although I believe that the evidence indicates that free immigration would be a net economic positive for receiving countries, I’ll set that claim aside for the sake of argument.
So, should we reject freedom in immigration in practice?
No, and here’s why: if preventing an increase in the consumption of state-provided benefits justifies restricting freedom in immigration, then it also justifies restricting freedom in, well, anything.
Consider that libertarians oppose laws restricting people’s ability to do things like consume drugs and sugary beverages, gamble their savings on professional sports, ride motorcycles without helmets, etc. But note that a major argument made on behalf of supporting these laws is that they prevent an increase in the consumption of state-provided benefits. People who ruin their health and their finances are more likely to avail themselves of state assistance. Still, libertarians reject these laws—not just in principle, but here and now.
I see no reason to treat free immigration differently. (Indeed, if anything, we have far stronger reason to permit free immigration because it would produce significantly greater gains in human well-being than, say, helmetless motorcycle riding.) Now, you might zig where I zag: you could support ending the drug war, legalizing gambling and helmetless motorcycle riding, etc. only in principle but not in practice. This view reduces civil and economic libertarianism to a project without much real-world import. And maybe this is the view you take (although I doubt it). But if you don’t, then you should support people’s right to immigrate in the real world at least as strongly as you support their right to drive a car without wearing a seatbelt.