I am not surprised that Bernie Sanders is opposed to open borders. There is a long tradition of socialists, labor unions, and Marxists opposing open borders in the United States. Many left-wing intellectuals oppose liberalized immigration, let alone open borders, because it will destroy political support for redistribution and state control of the economy – and they might be right.
However, I was surprised by the poor arguments made by Richard Eskrow in defense of Sanders. On how immigrants affect Americans, there is little difference between the expressed opinions of Senator Sanders and Senator Sessions (see here for a rebuttal I wrote to Senator Sessions, some of the following is borrowed from it). Senator Sanders, at least, wants to legalize the unauthorized immigrants who are here and probably doesn’t want to seriously limit future immigration.
Below I will block quote Eskrow’s arguments and respond to each one.
“Like many libertarian ideas, ‘open borders’ is bold, has superficial intellectual appeal – and is incapable of withstanding thoughtful scrutiny. It would benefit the wealthy few at the expense of the many, here and abroad.”
One of the main criticisms of immigration by restrictionists is that poor immigrants gain far more than Americans do. Harvard professor George Borjas’ famous paper on the wage effects of immigration found that Americans benefitted very slightly from it while almost all of the gains go toward the immigrants themselves. Even excluding the economic benefits to the immigrants themselves, poor Americans just aren’t hurt by having more people here. Borjas did find that immigrants decrease the wages of lower skilled Americans relative to higher skilled American, but his work is the most negative in the economics literature and should be taken with several big grains of salt. In that paper, he holds the supply of capital as fixed – an assumption that may be fine for an academic publication but it is not useful for making an argument against immigration in the real world. The stock of capital is dynamic and increases with the population. Ignoring that important effect would make any increase in population decrease wages. It should further be noted that Borjas, like other economists, admits that immigration does help Americans more than it harms them, but with some distributional consequences.