Charles Murray stakes out a moderate libertarian position on immigration policy at National Review Online. Regarding illegal immigration, he offers the following principles:

1. Making laws about who gets to become a citizen, under what circumstances, is a legitimate function of the state.

2. Protecting borders is a legitimate function of the state.

3. Enforcing the law is a central function of the state.

4. Immigration reform must begin first with enforcement of existing immigration law. If it takes a wall, so be it.

It’s hard to disagree with (1) or (3). Everyone of course agrees with (2) when it comes to protecting borders against terrorists and invading armies. But I’m not keen on “protecting borders” against tourists and workers. I would prefer the pre-1914 world without passports. A wall along the Mexican border isn’t helpful against terrorists or invading armies.

On legal immigration, Murray declares:

2. Massive immigration of legal low-skill workers is problematic for many reasons, and some of them have to do with human capital. Yes, mean IQ does vary by ethnic group, and IQ tends to be below average in low-job-skill populations. One can grant all the ways in which smart people coming from Latin American or African countries are low-job-skill because they have been deprived of opportunity, and still be forced to accept the statistical tendencies.

But why is immigration of low-IQ workers a problem? As Bryan Caplan points out, the Law of Comparative Advantage shows that we gain from hiring people whose human capital differs from ours.

Here is Murray’s key policy recommendation:

4. When it comes to the nitty-gritty, I would … make immigrants ineligible for all benefits and social services except public education for their children.

Privatize the provision of education, and I’m agreed. Immigrants who come to work, good; immigrants who come to sponge, bad. But sponging by US citizens is likewise undesirable. The more we reduce the incentives or eligibility to sponge by US citizens as well, the less different need be the eligibility rules for immigrants.

I like what William Leggett had to say on the topic long ago:

But with regard to these poor creatures who are flocking to our country as the boasted asylum of the oppressed of all the world, we ought to welcome them hither, not meet them with scowls, and raise a deafening clamour to excite unkindly prejudices against them, and drive them back from our inhospitable shores. For our part, we open our arms to them, and embrace them as brothers; for are they not a part of the great family of man? ... We are not bound to support them; they must support themselves. If they are idle, let them starve; if they are vicious, let them be punished; but, in God’s name, as they bear God’s image, let us not turn them away from a portion of that earth, which was given by its maker to all mankind, with no natural marks to designate the limits beyond which they may not freely pass.