For libertarians to promiscuously invite anybody and everybody to move in is like inviting drunks to join your AA chapter. Soon they'll outvote you and use your dues money to build stills and breweries, and supply booze stamps to the population at large. But a certain brand of ditzy libertarian insists that it would be immoral not to welcome them in. Logically, of course, that means that by their lights, libertarianism is impossible or at least not sustainable for more than a generation at best.
Matt Bailey alerted me to this piece by Eli Harmon:
Some, like Bryan Caplan [link], are fond of touting the benefits of immigration. These are real, but I think -- on the other hand --Caplan's treatment of the costs are, most charitably interpreted, naive and careless.
Wherever you look, xenophobia, in some form, and to some extent, appears close to a human universal.
Which hypothesis seems more plausible, that across time and space, human have consistently and persistently erred in precisely the same, costly (according to Caplan) way? Or that xenophobia might have some adaptive value?
I happen to think that America (in particular) and the west (in general) have peoples and cultures worth preserving. There are some distinctly beneficial features of these which would tend only to be attenuated by large-scale immigration of non-western foreigners. (Or even, in some cases, by western ones.)
But even setting this aside, there are benefits to homogeneity and costs to heterogeneity which probably should not be ignored.
One objection would be that to the extent that our institutions are democratic (which is somewhat) they're not capable of resolving conflicting imperatives but only of privileging some over others. "Multicultural democracy" is a joke.
(BTW, the interests that are privileged need not be those of the majority. See: the problem of concentrated benefits and diffuse costs.)
It isn't just a matter of democracy (for example) "not working." Democracy works fine for particular purposes. It's an eminently suitable form of government for a corporation because shareholders' interests are perfectly aligned towards maximization of profit (to the extent that shareholders are distinct from customers or employees.)
This is why democracy works relatively better in Denmark than in, say, Iraq. Denmark is less diverse, and the interests of Danes are more closely aligned.
So I feel pretty confidant in making the following prediction; among successful polities, the most "diverse" must be the most authoritarian or autocratic, while the most "democratic" or "liberal" (in either sense) must be the most homogenous. Which approach is better? Probably there's room in the world for all of these. But I don't think they can be combined into a single, successful, polity.
A more authoritarian regime may be able to realize the benefits of diversity and pass them on to its subjects (e.g. Singapore) by containing its costs where a democratic one would be plagued by rent-seeking or a libertarian one by free-riding if it were to permit the same.
Now, I like liberty. But it's empirically verifiable that it isn't most people's top priority. And even among those for whom it is, there are many different, sometimes incompatible, ways in which they may conceive of and prioritize it. So if I want to live in a stable polity that prioritizes liberty (in the way that I do) most people need to be excluded from it.
That just seems to be the way it is.
Quibcag: The excluder is one of the girls from K-On! (けいおん! Keion!)