Paul Krugman exemplifies the standard progressive position on immigration.  He strongly supports amnesty for existing illegal immigrants, but strongly opposes open borders.  His case for amnesty is not novel:

[T]oday’s immigrants are the same, in aspiration and behavior, as my
grandparents were — people seeking a better life, and by and large
finding it.

That’s why I enthusiastically support President Obama’s new immigration initiative. It’s a simple matter of human decency.

Krugman’s case against open borders, in contrast, is uniquely his own.  How so?  Most thinkers who explicitly reject open borders are convinced it would be an absolute disaster.  Krugman, in contrast, opposes open borders for the mildest of reasons.  Read his sentences carefully:

The New Deal made America a vastly
better place, yet it probably wouldn’t have been possible without the
immigration restrictions that went into effect after World War I. For
one thing, absent those restrictions, there would have been many claims,
justified or not, about people flocking to America to take advantage of
welfare programs.

Krugman hardly sounds convinced that immigrants would have flocked to the U.S. to take advantage of the New Deal.  “Justified or not” is awfully agnostic.  While Krugman says the New Deal probably wouldn’t have been possible without immigration restrictions, he doesn’t say that immigration restrictions were required to have some version of the welfare state.  Nor does he sound convinced that fear of “flocking” would have a high probability of substantially curtailing the welfare state in some form or other.  “Many claims”?  Name any major social program that fails to inspire “many claims” about its dangers before, during, and after its adoption.

Krugman continues:

Furthermore, open immigration meant that many of America’s worst-paid
workers weren’t citizens and couldn’t vote. Once immigration
restrictions were in place, and immigrants already here gained
citizenship, this disenfranchised class
at the bottom shrank rapidly, helping to create the political
conditions for a stronger social safety net. And, yes, low-skill
immigration probably has some depressing effect on wages, although the available evidence suggests that the effect is quite small.

Notice: Krugman doesn’t say that exclusion of immigrants was an essential political condition for the welfare state to arise.  He only says that it helped create political conditions for a stronger welfare state. 

So let’s sum up Krugman’s case against open borders:

1. It’s unclear whether immigrants would have flocked to the U.S. to take advantage of the welfare state.

2. But many would hastily assume such an effect, somewhat reducing domestic support for the welfare state. 

3. Also, excluding non-voting poor immigrants somewhat altered voter demographics in the welfare state’s favor.

Personally, I think that mass immigration does far more good for the truly poor than the welfare state ever has.  This isn’t just a weird libertarian view; Brad DeLong agrees with a few caveats:

Increased immigration is superior to strengthening the welfare state. I
just don’t think it will or can happen, so I will advocate the next
best thing. From a cosmopolitan world perspective, almost all of the
costs of maldistribution come from income gaps between nations and very
little come from within-nation inequality. Development is far more
important from a world welfare perspective than social insurance within
rich countries. And immigration is a powerful tool for world

But maybe Brad and I are wrong.  Suppose that if we faced an either-or choice between the welfare state and open borders, we should choose the welfare state.  Krugman still fails to provide any decent argument against open borders.  How so?  Because marginalism.  Krugman claims nothing stronger than, “Open borders would have somewhat reduced the strength of the safety net.”  Why then is he so convinced that this marginal policy change outweighs the massive harm inflicted by making almost all immigration illegal?

This is no hyperbole.  Joel Newman shows that the cost of immigration restrictions were already catastrophic by the end of Roosevelt’s second term, when the U.S. turned away hundreds of thousands of people desperately struggling to escape the clutches of the Nazis.  And far more would have applied if they had any hope of getting in – as millions did before World War I.

About a month ago, Krugman ridiculed lingering right-wing fear of democratic expropriation:

For the political right has always been uncomfortable with democracy. No
matter how well conservatives do in elections, no matter how thoroughly
free-market ideology dominates discourse, there is always an
undercurrent of fear that the great unwashed will vote in left-wingers
who will tax the rich, hand out largess to the poor, and destroy the

Krugman’s right.  This is a silly fear.  Why?  Many reasons, but the most obvious is that voters are far from selfish.  Most poor voters would consider full-blown expropriation of the rich to be deeply unfair, all incentive effects aside.

What the history of immigration restrictions shows, however, is that decent folk should nevertheless be deeply uncomfortable with democracy.  Why?  Because most voters are nationalists, and nationalist voters consistently do to foreigners what low-income voters almost never do to the rich: Strip them en masse of their basic rights to work, reside, and travel.  Why?  For the flimsiest of reasons.  Flimsy reasons like: Trapping millions of foreigners in dire poverty and bloody repression probably makes our safety net somewhat stronger.

To quote GMU econ prodigy Nathaniel Bechhofer: Paul, you’re better than this.