Matthew Yglesias scorns the notion of building a double wall on the Mexican border to reduce illegal immigration:

My colleague Andrea Nill notes that this is a fairly costly endeavor:

U.S. government investigators have indicated that it will cost taxpayers $6.5 billion over the next 20 years to maintain the fencing already in place and the Congressional Research Service estimated in 2007 that building and maintaining a double set of steel fences along 700 miles of the U.S.-Mexico border would add up to $49 billion over the expected 25-year life span of the fence.

That’s a lot of money to spend on an enterprise that, if successful, would reduce GDP and lower wages for most native-born Americans.

There's a general tendency among people of all ideological stripes to adopt a can't-do posture toward activities they just don't want the government to do. And some things are genuinely difficult for governments to do. Building a border wall isn't one of them. $49 billion over 25 years, or $2 billion a year, isn't that costly.

Yglesias argues that illegal immigration helps America's economy. But maintaining lax borders isn't really a good solution to immigration policy. If we want more immigration than the law allows -- and I think we should -- then we should raise the legal amount of immigration. Letting people in on the basis of their willingness and ability to evade border guards is not a rational approach. Yglesias argues:

Beck and Liddy, by contrast, are talking about a wall to keep out Mexicans who want to reach voluntary agreements to perform work in exchange for money. It’s about the least-nefarious plot of all time.

Sure, but that's an argument for unlimited immigration. It's not like liberals think absolutely any agreed-upon contract between two adults should be allowed. I can't sell Bill Gates my kidney because he'd like to have a spare one on ice just in case. Nor could I go work for Yglesias as his full time assistant for three dollars an hour. Just because an agreement isn't nefarious, it doesn't follow that it can't be prohibited or that the prohibition can't be enforced. Maybe we do want unlimited immigration. If we are going to have some limits on immigration, though, you're going to have to enforce them in some way.

I think the strongest argument against a serious wall on the Mexican border is that it would send a terrible message about America's openness to Mexico and the world. The costs of that symbolism might well be worth any benefit of reducing illegal immigration. Still, I could imagine some kind of deal that involved the construction of serious barrier to stop illegal immigration along with an increase in legal immigration and some amnesty for illegal immigrants. The proper grounds for liberals to fight on immigration are on immigration levels and humane treatment of legal and illegal immigrants, not on enforcement of the law.

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