But I thank Will Wilkinson for calling that to my attention.
More seriously, I think Will is slightly misreading my original post, in which I was setting forth what I think are many liberals' unspoken premises about policies that allow for large-scale immigration - namely, that they're a form of de facto humanitarianism, and thus to be supported. I do not believe myself that "voluntary trade between American employers and Mexicans workers [is] equivalent to 'humanitarian spending.'" Rather, I believe that many people on the left think this way, at least in some sense (at the very least, it seems clear to me that most liberals don't support immigration for the same "voluntary trade 4Ever" reasons as Will and the Wall Street Journal), and so I was trying to argue with them on those grounds.
But Will is of course right that I don't share his premises either. For instance:
That Ross is liable see the issue in this weird, mistaken way does indicate that he thinks some sort of nationalism is the legitimate moral baseline. The liberal (in the broad sense) presumption of freedom, on the other hand, has it that unrestricted voluntary cooperation between human beings is the moral baseline. Deviations from this require special justification.
I suppose I prefer to think that constitutionalism and Judeo-Christian ethics are the moral baseline where government action is concerned. That is, I believe that the government of the United States should strive to "form a more perfect union, establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity," and do so without trampling on any of the liberties enumerated in the Constitution; at the same time, I would prefer that America's leaders pursue policies that are broadly consonant with the Judeo-Christian tradition. (No wars of aggression, for instance.) And I'm pretty sure that "unrestricted voluntary cooperation between human beings" isn't a liberty that the Constitution protects, since the Congress is explicitly granted the power to regulate both interstate and international commerce. (In the final chapter of Atlas Shrugged, we encounter one of Rand's Supermen rewriting the Constitution to include a clause reading "Congress shall make no law abridging the freedom of production and trade," but I don't believe that amendment has been ratified.) I certainly prefer that this power be used prudently, and I'm open to persuasion that policing the borders of the United States is an imprudent application of government power. But preventing American businesses from importing their workforce from abroad simply isn't a "basic violation of liberty" under our political order in the way that, say, restrictions on religion or political speech would be. Of course Will is entitled to make "unrestricted voluntary cooperation between human beings" his moral and political baseline - he just isn't entitled to pretend that this principle is a baseline that everyone who participates in the liberal order is required to share.
The question of whether restrictions on immigration from poor countries to rich ones violate Christian teaching - since they clearly don't run afoul of the American political order - is a much more complicated one, touching on all sorts of debates too involved for this blog post. Suffice it to say I think that the answer is no; a rich Christian country should be favorably disposed toward immigration, I would argue, but I don't think Christianity provides any sure guide to exactly how favorably disposed it should be. There are all sorts of variables that the government of a Christian society should weigh when deciding how many migrants to admit, chief among them the effect of migration on civil peace and political stability, both of which are taken somewhat for granted in contemporary America but which have historically been rather fragile things. How to weigh these variables is a point on which intelligent people, Christian and otherwise, can disagree. The Economist's blog (or Maybe Megan McArdle) recently suggested, for instance, that America's foreign-born population could grow by 50 percent or more from where it is today without causing any unacceptable risks to the body politic; I'm not persuaded, but it's an argument worth having. What isn't an argument worth having is whether admitting, say, only 300,000 newcomers a year to our political and social order, rather than over a million, is the moral equivalent of Jim Crow.
As for whether I wish the U.S. to be "less Mexican," I would like to associate myself with Daniel Larison's comments and leave it at that.