In particular I noted the line, when CNN asked "You wish to give illegal immigrants and refugees free health care and education, how does that not make every person want to travel to the United States and become a citizen?" and he deflected and dodged the question. I don't necessarily think it was the wrong move, because the question is a bait question by CNN, but it would have been more interesting to hear him rebut that in some way. I think the question itself had merit, as I don't personally believe that open borders is the ideal solution right now (long term it is absolutely the best way for society to progress but the United States simply cannot be expected to carry the burden of every refugee from Latin and South America, as well as Europe and elsewhere, and the load has to be distributed so as not to create further poverty). Warren stood out more than Sanders for this as her "I have a plan for that" is good press.
So Bernie's views on immigration are in some ways far left of the field and in others right of the field... In that he believes in eliminating the vulnerability of immigrants within the boarders, but believes in strong borders and limited immigration. On access to healthcare, education, social services, path to citizenship and even voting Bernie is far left in giving them to undocumented people, but there's going to be less coming in under a president Sanders than Castro or probably Warren. In the past (and I believe even now) he's been an advocate for rolling back migrant worker visas and overall restricting immigration-- you heard it in the debate too, when he answered "because we'll have strong border protections." I agree he didn't flesh out the reasoning, but he didn't mis-characterize his beliefs.
So what is the reasoning? I've never heard Bernie outline the reasoning for it anywhere, but I've heard Socialist professor Richard Wolf argue for a set of policies that are quite aligned with Bernie's-- strong boarders, but full access for all people in the boarders.
TLDR:
-Immigrants are a subsidy to employers, by inflating supply of labor which depresses prices (wages).
-Immigration has always increased or decreased based on policies decided on by politicians owned by the wealthy. They control the mechanism that sets the level of immigration.
-In particular, VULNERABLE labor (undocumented people) can be easily co-erced into awful conditions, which further subsidizes the employer and depresses wages.
-SO to prevent this from happening, you guarantee economic rights for EVERYONE. Healthcare, education, citizenship, housing, a decent income and opportunity to work.
-How will we make these services or pay for the projects that will employ all living in the boarders? We tax the rich.
The result: In these circumstances, increasing immigration does not deflate wage prices or standards of living for citizens. Instead new immigrants then represent new tax burden for the rich.
Summary
So instead of workers being obligated to fight poor immigrants or fight for their economic rights, it becomes the job of the bosses of the country to make sure that when they let anyone in, it's because they
need more people and are willing to treat their new employees well.
Bernie's immigration policy is aimed at creating a stable market back home, that delivers economic justice for the people in the boarders... but only within the boarders.
Now, this position itself, this logic itself has its own moral quandries because it is ungracious to people outside the country. Spelled out, I think the American people will take issue from all sorts of angles (right and left, good and bad faith). It's definitely not even fully agreed on within Democratic Socialists, and there are people like AOC, more radical than Bernie and likely sympathetic to going straight to open boarders and international worker solidarity, without patience for what ultimately amounts to incrementalism within socialist thinking. That said, if you want the rationale for Bernie's views on immigration, this is probably what it is.
Frankly, I think that this type of incrementalism is required. I think Bernie ultimately believes in worker solidarity across boarders, and in one day executing a massive foreign aid program to help rebuild places around the world-- this is how he's outlined his views on foreign policy. But he is a man of the people under his democracy, and you can tell that Bernie prioritizes them... if you don't have the people on your side to begin with, you cannot do anything else; especially if like Bernie you believe so heavily in democracy. So his policies on immigration come from a socialist ideology, but have incrementalism inbedded-- you have to make the American workers wealthy and generous to the world, first get their mandate, before you can open the boarders or massively invest abroad.
Not fully laying it out in these terms, is probably a political calculation on Bernie's part. Bernie is an honest man, but in terms of academic explanation for what he believes, it often feels like he purposefully avoids it. But if you listen to tapes of young Bernie, or you listen to academic discussion between socialists elsewhere, you can learn the logic that doesn't get spelled out like a term paper from Sander's own lips.
