When the Berlin Wall came down, the whole world rejoiced. Onlookers said, “At last, the East Germans will be free”—not “The West Germans are about to lose their freedom to a horde of communist immigrants.”1

Caplan believes that if someone wants to come to the US, our default response should be to let them. He clarifies the kind of “open borders” he supports as follows:

Critics occasionally equate “open borders” with “no borders,” but these are distinct proposals; an open borders regime could still have border checkpoints, require passports, and so on. The acid test, in my view, is that an open borders regime does not subject foreigners to any mobility restrictions more stringent than natives face. Thus, if a foreigner commits a crime warranting incarceration, an open borders regime could impose the lesser punishment of exclusion. Similarly, if a foreigner has a contagious disease warranting quarantine, an open borders regime could impose the lesser precaution of exclusion.2

There are two basic prongs to his argument, one ethical and one economic:

For me, the ethical reasons are the decisive ones. Immigration restrictions are fundamentally based on violence: people who do not adhere are forcibly imprisoned or deported. I think violence should be assumed to be wrong by default unless very compelling reasons for its necessity have been presented. Do we have compelling reasons to keep most people out of the US by violence?

Some arguments for keeping people out seem morally bankrupt even if you grant their empirical assumptions. Suppose that, contrary to Caplan’s economic arguments, more immigration would make current US residents much poorer and make our lives worse. That would suck, but it wouldn’t justify the use of force. I don’t get to tell people from a neighboring city that they can’t live in my city just because I’m afraid they’ll compete with me—or my (hypothetical) children—for jobs. It seems equally unjustifiable to tell people they can’t live in my country because I don’t want to compete with them. (There might be an argument that it’s even less justifiable: being kept out of the entire US puts you at a much greater disadvantage in life than merely being kept out of, say, Seattle would.)

Caplan addresses several other concerns, including:

One chapter is devoted to the notion that, even if you think some of the concerns motivating limited immigration are valid, there are other ways to address those concerns. We could charge immigrants an entry fee or make them pay higher tax rates; restrict their access to public services; make them pass language or cultural literacy tests; make them jump through extra hoops to attain citizenship and the right to vote; etc. Caplan’s not advocating for any of those policies, just identifying them as potential compromises that would be improvements over the status quo. Because the status quo is pretty extreme; lots of people simply have no legal route by which to live in the country they want to live in. Even offering them an unfairly shitty route would be an improvement.

The book is illustrated by the creator of SMBC, so there are some pretty funny jokes sprinkled throughout the drawings.