Why are citizenship and working bundled?

In re guest workers, Kerry responds:

Citizenships are club memberships you happen to be born with. Some clubs, like the Norway club, have truly awesome benefits. Others, like the Malawi club, offer next to none. Membership in each club is kept limited by club members, who understandably worry about the drain on resources that new members might represent. Wishing the U.S. would extend more memberships in 2008 isn’t going to get you very far.

Conceptually, for whatever reason, most of us are in a place where we think labor market access and citizenships ought to be bundled. A Malawian can’t come work here, we think, without the promise of a club membership, which is nearly impossible to get. This is an incredibly damaging assumption for two reasons: (1) memberships are essentially fixed in wealthy democratic societies (2) uneven labor market access is a major cause of global inequality. Decoupling the two leads to massive gains, as we see in Singapore, without the need to up memberships.

Question: what's the difference between outsourcing and immigration? To an economist, perhaps not much; they both cause relative adjustments in some wages while producing gains from trade. To the rest of us, however, there are large and noticeable differences. Immigrants produce substantial externalities, positive and negative, in the communities they inhabit. Citizenship doesn't come bundled with the right to work for American companies; it comes bundled with the right to work for American companies here. And it does so for the very good reason that one's neighbors have a very large impact on one's life. We may some day transcend geography, but right now we're all very much locked to a small patch of earth, and the people who happen to be inhabiting the patches next to us.

I am of the opinion that the positive externalities outweigh the negative ones, particularly when we consider, as I believe we should, the benefits to the migrants. But there are ways to amplify the negative externalities, and setting up a program that explicitly prevents assimilation seems like a big one. So does setting up a program which, in order to actually make it work as promised, would require massive changes to American institutions such as gender discrimination laws.

I don't think that most supporters of guest worker programs actually envision them working as promised; I think they anticipate substantial leakage from the program, rather than anticipating that we will, say, suddenly start discriminating against female immigrants. Probably they're right. But I get hopping mad every time I see a politician lowballing the cost of his latest healthcare boondoggle, so I don't feel entitled to work similar tricks on people I disagree with. And in the long run, I don't think it will work. Programs sold on exaggerated promises, like the Medicare subscription drug benefit, survive because they create their own constituency against changing them back. But if this program works as advertised, its major beneficiaries won't ever be able to vote.