Christopher Freiman has a paper coming out called “The Marginal Cases Argument for Open Immigration.” I’ll briefly summarize it here. I probably have lots of typos. Oh well.

Freiman wants to argue for open borders using a move Peter Singer made when discussing animal rights. Singer says to readers (this is a paraphrase, not a real quotation): “Okay, so you believe it’s permissible to eat animals and perform medical experiments on them, but not permissible to eat humans or perform experiments on them (without their consent). Fine. Give me some feature F that humans have, which non-human animals lack, that plausibly explains why it’s prohibited to eat and perform experiments on one but not the other. And you can’t just say F = is human, because that’s the very thing we’re asking about. What it is about being human that makes it wrong to treat them the way everyone thinks it’s okay to treat non-human animals?”

The reader/hypothetical dialogue partner then offers a range of possible Fs, such as “possesses free will” or “is a moral agent” or “has autonomy” or “has the capacity to reason” or “has the potential to develop the capacity to reason”.

But for every putative F that people identify, Singer responds, “Okay, but here’s the problem for your putative explanation. I can point to a bunch of non-human animals that have more F than a bunch of humans. For instance, this cow might have more autonomy or capacity to reason than this mentally disabled person. This chimp might have more potential to develop the capacity to reason than this terminally ill toddler. So, if F–the explanation you supplied–really were what explains why we can eat or perform certain invasive medical experiments on non-human animals, then you ought to agree that I can eat or perform those invasive experiments on these people.” So, it seems, Singer catches people in a trap. They must either bite the bullet and say, “Yes, eat the mentally disabled person if you so desire,” or admit that F isn’t really a good explanation of the difference. After all the plausible Fs run out, Singer thinks you’re stuck admitting that maybe we shouldn’t eat animals or perform certain invasive experiments on them.

Freiman makes a similar move. Freiman says to readers (again, a paraphrase, not a real quotation): “Okay, so you believe it’s permissible to prohibit foreigners from moving to your country (even when there’s someone who wants to hire them or let them lease a house), but it’s not permissible to deport current citizens. Fine. Give me some feature F that citizens have, which non-citizens lack, that plausibly explains why it’s permissible to exclude one but not to deport the other. Or give me some feature G that non-citizens have, but citizens lack, that explains why it’s permissible to exclude foreigners but not deport citizens. Let’s confine ourselves to cases where the harm done to the foreigner by excluding him is equal to the harm done to the citizen by deporting her. And, no, you can’t just say F = is a citizen or is a member of the social contract, or that G = is a foreigner or is not a member of the social contract, because that’s the very thing we’re asking about. What is it about natively-born people that they count as having certain rights while foreign-born people don’t?”

The reader/hypothetical dialogue partner then offers a range of possible Fs, such as “enhances our culture” or “speaks our language” or “improves our wealth” or “is a net taxpayer.” Or the reader offers a range of possible Gs, such as “will be a net tax consumer” or “may depress domestic wages” or “belongs to a religious group more likely than average to produce Charlie Hebdo-type attacks” or “might sully our culture” or “belongs to a demographic more likely to commit crime” or whatnot.

For every such putative F or G that people offer, Frieman responds, “Here’s the problem for your putative explanation. I can point to a bunch of foreigners who have more of good thing F than most or many citizens. I can point to a bunch of foreigners that have less of bad thing G than many or most citizens. Etc. So, for instance, if “might commit crime” is a reason to exclude Mexicans, then we should deport most poor domestic-born citizens, regardless of race, since as a matter of demonstrable fact, they are statistically more likely to commit crime then Mexican-immigrants. If “they might consume more taxes than they pay” is a reason to exclude Haitians, isn’t it also a reason to deport American citizens who are likely to be net tax-consumers? If “will vote for religious rules as law” is a reason to exclude Arabs, isn’t it also a reason to deport many conservative Christians? “They might vote badly” is a reason to deport almost every American. “They might consume too much welfare” is a reason to deport all these damn baby-boomers who wrongfully chose not to save enough for their retirements. And so on.

So, Freiman catches people in a trap. They must either bite the bullet and say, “Yes, let’s deport all white people from Mississippi born to families with incomes lower than…,” or they must admit that F and G weren’t good grounds for treating foreigners and domestic-citizens differently. After all the plausible Fs and Gs run out, Freiman thinks you’re stuck admitting that we shouldn’t exclude foreigners.