How much do human beings differ from each other? I am not sure that either answer to this question– people differ a lot or people are fairly similar— systematically favors either answer to the question of open borders, but it affects how the case for or against open borders should best be made. Thus, one might plausibly argue any of the following:
1. Large Human Differences => Pro Open Borders. People are very different, so they have a lot to gain by trading with and learning from each other. Immigrants bring very different habits and cultural outlooks, which enables them to see entrepreneurial opportunities that natives miss, enjoy jobs that natives hate, and make art, cuisine, and music that will surprise and fascinate natives. Competition from immigrants is an overrated problem because immigrants won’t like the same things or have the same skills as natives do.
2. Large Human Differences => Anti Open Borders. People are very different, and cooperation works best in fairly homogeneous cultures. Cultural differences make it hard for people to understand each other, leading to conflict and/or alienation. A lack of trust will lead to higher transactions costs, weaken institutions, and make political order hard to sustain.
3. Small Human Differences => Pro Open Borders. People aren’t that different, so a developed country that embraces open borders will find it fairly easy to assimilate people from all over the world. They’ll find the local rules and protocols understandable and easy to adapt to, and other than there being a greater variety of skin colors on the street, countries will look pretty much the same after as before open borders.
4. Small Human Differences => Anti Open Borders. People aren’t that different, so open borders won’t really give rise to a rich diversity, because foreigners are basically just more of the same. The fun of learning about foreigners’ art, music, cuisine, ideas, etc. will be quickly exhausted, because the differences just aren’t that important. They’ll like the same things we do, and have or quickly acquire similar skills, so the main effect of open borders will be more competition for scarce resources, such as spots in Harvard’s entering class, or California beachfront land.
Those are just a few examples to illustrate why views of human differences should not be expected to map into views on open borders in any straightforward way. But views on human differences will tacitly or explicitly condition the open borders debate, so I want to offer an answer of sorts to this important question.
My answer takes the form of a mnemonic metaphor, summarizing a wide variety of impressions, which I think– though of course I can’t prove it, or even propose a way to test it– gives a pretty good idea of just how much human beings differ, namely: Human souls differ about as much as dogs’ bodies do. Which is to say, a lot, but we can still recognize a common human nature in all human souls, just as we can recognize canine features in all sorts of dogs, from the tiny Chihuahua…
… to the enormous Newfoundland…
Dogs come in colors from white to rust to grey to yellow to chocolate to black, but they all have four paws, nose, two ears, two eyes, and a mouth with sharp teeth. All dog breeds have tails and fur, though both of these vary in length. It’s really rather incredible that canis lupus familiaris is one species, and that such potential for phenomic diversity turned out to inhere in a certain European wolf a few thousand years back. What would the originals of that species think of the enormously varied descendants they would have, as a result of befriending a certain clever primate? Yet no one doubts that “dog” refers to a coherent category of things, or has much trouble distinguishing a dog from a cat. Likewise, one can recognize a common humanity in its manifold and extremely diverse manifestations.
Human appearances differ, I think, much less than those of dogs. No race of human beings is 10+ times larger than another race, as Newfoundlands are 10+ times larger than Chihuahuas. Facial features, e.g., nose length and ear shape, vary less. But these surface similarities mislead, and between the mild, celibate scholar and the swaggering pirate; the ascetic saint and the sultan in his harem; the decadent poet and the toiling Christian peasant; the Wahhabist fanatic and the urbane atheist; the illiterate Somali farmer and the Norwegian petroleum engineer and the Japanese salaryman; Achilles and Socrates; Genghis Khan and Samuel Johnson; King Tut and Saint Peter; Queen Victoria and Lady Gaga; the spiritual differences are, I think, roughly as great as the physical differences between a Chihuahua and a Newfoundland.
The classical list of seven virtues– courage, justice, temperance, prudence, faith, hope, and love– provides a useful key to both the unity of human nature, and the diversity of its expressions. I am not such a cultural anthropologist as to have checked the following claims against every human culture (nor is anyone else) but I’ll nonetheless assert the following without much fear of informed and convincing contradiction:
1) Every culture admires people who can face peril or pain when they believe it is right, and disdains those who always give way to their fears. (Courage)
2) Every culture has some form of the notion of rights and/or property, of what is due to each individual, and distinguishes deserved from undeserved suffering. (Justice)
3) Every culture is familiar with the experiences of addiction and short-sighted pleasure-seeking, and encourages and applauds the willpower and self-control that enables some people to govern their passions and appetites. (Temperance)
4) Every culture respects thinking, planning, weighing evidence, and careful determination of the best means to pursue a given end. (Prudence)
5) People in every culture project certain desires onto the future, aim at them, and labor with a view to bringing them about, while regarding despondency and despair with aversion and disapproval. (Hope)
6) People in every culture hold and value beliefs not logically provable, and feel loyalties related to their own past or that of their family, their country, and/or some other community to which they (feel they) belong. (Faith)
7) People in every culture delight in contemplating, and will the good of, certain other people, as well as many other things, such as mountains, stars, trees, hearth and home, food, songs, stories, holidays and festivals, and/or God. (Love)
While all humans share courage, justice, temperance, prudence, faith, hope, and love, they clearly differ greatly in the degree to which they possess these virtues, and in the ways they express them. One man has the courage to frame a bold new theory; another to speak to a crowd; another to charge into battle; another to scale the rocky face of El Capitan. Some, perhaps, are brave in all these respects; some, certainly, are brave in none of them. Some people are cynics and skeptics, and some have fewer loyalties than others, while among those who have strong faith, it often happens that what one holds sacred, another abhors, and one man’s dogma is another’s absurdity. One man thinks it just to execute the king’s orders, another to execute the king; one, that property is nine-tenths of the law, another that it is theft. Self-control might mean no sex, but a little wine and plenty of beer, to a medieval monk; no alcohol, but plenty of sex, albeit within marriage, to a modern Mormon; and free love and booze, but no animal products, to a contemporary vegetarian leftie.
While mortals ought not to judge particular cases, experience probably has made us all vaguely aware that some people are just rather deficient in virtue, not accomplishing much or even really trying, stewing in petty resentments, without many scruples about sex or money or lying, full of baseless pride and easily offended. Beware: there but for the grace of God go we, and we are probably much closer to that wretched state than we suppose. Others have more solidity about them, and can be relied on to tell the truth, to face dangers, to think clearly, to admit faults, to be fair, to give the largest share to others, to enjoy and to praise, to resist discouragement in difficulties, and/or to work hard. Virtue shines most in the course of stories and in the face of challenges. Virtue– this is the heart of the matter– makes us more real, and it is through the exercise of virtue that we become most characteristically ourselves. The saints are gloriously different, the tyrants tediously alike. Yet while virtue brings out what is uniquely valuable in each of us and makes it shine, it also makes us converge, grow more like, make contact, and understand each other. This point is so subtle– indeed it is a kind of pinnacle of wisdom, and I would never have seen it on my own, but am borrowing it from others like David Bentley Hart and C.S. Lewis and Alasdair MacIntyre and my sister Rachel Lu, the Catholic philosopher— that I am hardly up to the challenge of giving an example. But suppose the greatest jurists from the ends of the earth were brought together: wouldn’t they be able to explain and understand one another’s systems with a degree of ease and profundity that would baffle less wise and more dogmatic minds schooled in those systems? And wouldn’t the great minds across the ages, the John Lockes and the Aristotles, understand one another better than the myriad “Aristotelians” and “Lockeans” who fill in the gaps?
Now, there are two opposite errors into which people can fall with respect to human differences. On the one hand, one may exaggerate them, and become a cultural relativist like Clifford Geertz or Margaret Mead, or in a different vein Jean-Paul Sartre, denying that there is any essential human nature, and insisting that everything we take to be fundamentally natural or true or right is simply the artifact of a particular symbolic environment, and ultimately arbitrary. No. People have much more in common than that, and human nature and virtue are objective realities.
The other error is the one I think Bryan Caplan and Michael Huemer make in trying to found a political philosophy on “common-sense morality.” The problem with this project, in a nutshell, is that common sense is not common. To elaborate on that, what the phrase “common sense” will mean to the kind of typical Westerner who is the target audience of Caplan’s blog and Huemer’s book, is not actually something that all human beings as such have in common, but is heavily informed by the historical experiences of the West, which have given rise to certain values, ideas, and assumptions. In some respects, for example in its ideas about freedom of conscience and human rights, the West really represents the best that man has been and done and thought, and Western common sense really represents a truer view of reality, including moral reality, and a fuller human flourishing, than other cultures have attained. But even then, as other cultures have not attained to Western common sense, an argument from Western common sense is premature, as it does not appeal to premises they accept, and a prior task must be to raise them to the level of Western common sense through instruction and exhortation. In other respects, for example in much of what it says about “equality” and “democracy,” as well as in its weakness for philosophical materialism, Western common sense is a tangle of pious thinking and willful confusion that can’t stand up to serious critical scrutiny, and the modern West is inferior in wisdom and insight to the best pre-modern and non-Western thought.
If men’s souls are as varied as dogs’ bodies, and if one wishes to craft arguments that can appeal to all men, appeals to common sense morality are too local and facile. One must probe deeper and cast one’s net wider in order to learn better what human beings are, and what values and beliefs they really have in common. Only then will it be possible to make a truly universal case for open borders. I still have a doubtless very biased notion that a decent sketch of what that case would look like is contained in my book, Principles of a Free Society.