Last year Pope Francis visited the United States and addressed Congress. A significant portion of his speech was devoted to how people should respond to immigrants. While not appealing for specific immigration policies, Pope Francis reminded his listeners that immigrants deserve to be treated humanely:

“… thousands of persons are led to travel north in search of a better life for themselves and for their loved ones, in search of greater opportunities. Is this not what we want for our own children? We must not be taken aback by their numbers, but rather view them as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation. To respond in a way which is always humane, just and fraternal. We need to avoid a common temptation nowadays: to discard whatever proves troublesome. Let us remember the Golden Rule: ‘Do unto others as you would have them do unto you.’ This Rule points us in a clear direction. Let us treat others with the same passion and compassion with which we want to be treated. Let us seek for others the same possibilities which we seek for ourselves. Let us help others to grow, as we would like to be helped ourselves.”

Open borders supporters can highlight certain remarks that appear to support our cause, especially the sentence “Let us seek for others the same possibilities which we seek for ourselves.” For immigrants from developing countries to enjoy the same opportunities as people living in developed countries, they must be allowed to enter and remain in advanced countries. And it seems impossible to treat immigrants in a way that is “humane” and “just” under a policy of restrictions. (The group No One Is Illegal states that “the achievement of fair immigration restrictions… would require a miracle.”) At the same time, those opposed to open borders could reference a remark in the Pope’s speech (not quoted above) in which he states that the world refugee crisis “presents us with great challenges and many hard decisions.” One might infer that those decisions might involve accepting some migrants into destination countries and refusing others.

But what about the Golden Rule itself? Is it a foundation for open borders? One approach to the Golden Rule would seem to support open borders. Consider Bryan Caplan’s remark that all that we really owe strangers is to leave them alone. If this is applied universally, “Do unto others…” could mean that you wouldn’t have anyone block you from shopping, living, or working where you please, even if it’s in another country, so you shouldn’t interfere with others’ ability to do the same, regardless of their nationality. This seems to be what the Pope means when he says, “Let us seek for others the same possibilities which we seek for ourselves.”

The Golden Rule also could be seen as supporting a limited version of open borders. It would support open borders for citizens of countries with comparable economic prosperity. For example, Argentina, Chile, and Uruguay have roughly the same per capita GDP.  It would make sense that citizens of any one of these countries would have the other two countries allow them to migrate freely to those countries to pursue economic opportunities, so they should have open borders for citizens of the two other countries to enter their country.

However, the Golden Rule’s support for open borders could founder when applied to citizens of countries with wide economic disparities. This is because citizens of the Third World generally have much more to gain from moving permanently to the First World than citizens in the First World have to gain from moving permanently to the Third World. Citizens of developed countries, who generally have little desire to migrate to developing countries, probably wouldn’t have developing countries open their borders to them, especially if it meant they would have to, under the Golden Rule, reciprocate. Therefore, they wouldn’t be obligated to open their borders to citizens from developing countries. For example, most Canadians likely would be okay with Bangladeshis telling them that they couldn’t migrate to Bangladesh, so Canadians wouldn’t have to open their borders to Bangladeshis. On the other hand, most Bangladeshis probably would have Canada open its borders to them, so they would have to open their borders to Canadians. This difference in perspective reflects a weakness that others have noted about the Golden Rule: the difficulty of applying it to “differences of situation.”

Pope Francis’ comments about treating immigrants with compassion are inspiring. However, I disagree that the Golden Rule “points us in a clear direction” about how to respond to immigration. It is too malleable to provide a moral foundation for immigration policy.

In a previous post, I noted that, in my opinion, the best argument for open borders is that it would allow people, not their birthplace, to control their lives. Open borders would offer people who had the bad luck of having been born in poor and/or unsafe countries the opportunity to escape their unfortunate circumstances and find a better life in a safer, more prosperous country. It is wrong for the lucky who were born in the developed world to deny this opportunity to the unlucky who were born in poor countries, to paraphrase the ideas of several other critics of immigration restrictions.

How persuasive is this argument? Research on the role that awareness of one’s luck has on one’s generosity suggests that the argument, by reminding people of their good fortune in having been born in the First World, could be effective.

A recent article in The Atlantic by Robert Frank of Cornell University focuses on this connection between being aware of one’s good luck and a willingness to help others. Mr. Frank notes that when people disregard the role luck plays in their success, they are less generous. However, “… when people are prompted to reflect on their good fortune, they become much more willing to contribute to the public good.” He cites experiments in which subjects who are induced to feel grateful or consider factors outside their control that have helped them are more generous towards strangers than subjects in control groups.

It would be interesting to see what the results would be if a similar experiment were conducted in which some subjects were prompted to consider their good fortune at having been born in an advanced country and then asked their views on open borders, while other subjects were not given such prompts. The results of the aforementioned studies, even though the generosity was directed at strangers who were presumably fellow citizens, suggest that the subjects in the hypothetical experiment who were led to consider their good fortune would be more favorable towards open borders than the other subjects. (While he doesn’t express his views on immigration policy, Mr. Frank states that “the one dimension of personal luck that transcends all others is to have been born in a highly developed country.”)

As open borders advocates consider which arguments are most likely to convince more people in advanced countries to embrace open borders, this focus on making individuals aware of the huge role that their place of birth has had on their lives could be potent. Of course, this message would be received better by those who are prospering more than others. As the Brexit vote has shown, many of those who are struggling in the developed world are in no mood for increased immigration.

Mr. Frank observes that successful people in the First World tend to overlook the role luck plays in their success: “Most of them are vividly aware of how hard they’ve worked and how talented they are. They’ve been working hard and solving difficult problems every day for many years! In some abstract sense, they probably do know that they might not have performed as well in some other environment. Yet their day-to-day experience provides few reminders of how fortunate they were not to have been born in, say, war-torn Zimbabwe.” If the open borders movement can provide more such reminders, it could be significantly strengthened.