Just as the state shouldn't regulate imports and exports of goods, services and capital so it is wrong for the state to regulate immigration. The same principle is involved.
Of course I'd have made the usual caveats about the necessity of abolishing the welfare state before opening the borders, but opened they should be.
However, I'd have forgotten what had been written earlier by Murray Rothbard:
However, on rethinking immigration on the basis of the anarcho-capitalist model, it became clear to me that a totally privatized country would not have "open borders" at all. If every piece of land in a country were owned by some person, group, or corporation, this would mean that no immigrant could enter there unless invited to enter and allowed to rent, or purchase, property. A totally privatized country would be as "closed" as the particular inhabitants and property owners desire. It seems clear, then, that the regime of open borders that exists de facto in the U.S. really amounts to a compulsory opening by the central state, the state in charge of all streets and public land areas, and does not genuinely reflect the wishes of the proprietors. Under total privatization, many local conflicts and "externality" problems-not merely the immigration problem-would be neatly settled. With every locale and neighborhood owned by private firms, corporations, or contractual communities, true diversity would reign, in accordance with the preferences of each community. Some neighborhoods would be ethnically or economically diverse, while others would be ethnically or economically homogeneous. Some localities would permit pornography or prostitution or drugs or abortions, others would prohibit any or all of them. The prohibitions would not be state imposed, but would simply be requirements for residence or use of some person's or community's land area.This approach has been developed further by Hans-Hermann Hoppe here and here. Specifically, Hoppe denies that there is a similarity between movements of goods and movements of people:
Free trade and markets mean that private property owners may receive or send goods from and to other owners without government interference. The government stays inactive vis-à-vis the process of foreign and domestic trade, because a willing (paying) recipient exists for every good or service sent, and hence all locational changes, as the outcome of agreements between sender and receiver, must be deemed mutually beneficial. The government’s sole function is that of maintaining the trading process (by protecting citizen and domestic property). However, with respect to the movement of people, the same government will have to do more in order to fulfill its protective function than merely permit events to take their own course, because people, unlike products, possess a will and can migrate. Accordingly, population movements, unlike product shipments, are not per se mutually beneficial events because they are not always necessarily and invariably the result of an agreement between a specific receiver and sender.Complete private ownership of property would have radical implications:
Clearly, in this kind of society, there is no such thing as freedom of immigration, or an immigrant’s right of way. What does exist is the freedom of independent private property owners to admit or exclude others from their own property in accordance with their own restricted or unrestricted property titles. Admission to some territories might be easy, while to others it might be nearly impossible. Moreover, admission to one party’s property does not imply the “freedom to move around,” unless other property owners have agreed to such movements.In other words, under an anarcho-capitalist system the immigration question does not arise.
What about a society that does have a state, even a limited one?
...if the government admits a person while there exists no domestic resident who wants to have this person on his property, the result is forced integration.And his solution:
At all ports of entry and along its borders, the government, as trustee of its citizens, must check all newly arriving persons for an entrance ticket — a valid invitation by a domestic property owner — and everyone not in possession of such a ticket will have to be expelled at his own expense.Furthermore:
Hence, the admission implies negatively — similarly to the scenario of conditional free immigration — that the immigrant is excluded from all publicly funded welfare. Positively, it implies that the receiving party assumes legal responsibility for the actions of his invitee for the duration of his stay.That's pretty radical isn't it? But only a little more so than DK's proposal:
I repeat, you are not blocking the borders, merely vetting the people coming in and only blocking those whom you consider undesirable, i.e. economically or socially damaging.