Nor is this is just the oddball notion of some eccentric former staff member. As far back as August 2015, Mr. Trump himself has trotted out similar ideas, telling CNN, “the 14th Amendment is very questionable as to whether or not somebody can come over and immediately that baby is a citizen.” He also suggested that “you can do something fast” to end birthright citizenship. It may be time to revisit Arendt’s proposal.

For Arendt, the prospect of mass statelessness was particularly alarming. Since states are the only institutions able to guarantee rights, she wrote, “A stateless person is not just expelled from one country, native or adopted, but from all countries — none being obliged to receive and naturalize him — which means he is actually expelled from humanity. Deprivation of citizenship consequently could be counted among the crimes against humanity, and some of the worst recognized crimes in this category have in fact, and not incidentally, been preceded by mass expatriations.”

Arendt, a refugee from Nazi Germany who had been for a time stateless herself, had observed how, during the Holocaust, Jews had first been rendered stateless and how this had prevented their escape and facilitated their mass killing.This may seem like a remote possibility today, but it’s important to remember the stakes and meaning of statelessness.

It should be noted that it’s currently extremely difficult to denaturalize an American citizen, and it almost never happens. Even during McCarthyism, when there was the political will and legal machinery to expatriate people, the process was slowed down considerably by procedure and the courts. And in 1958, the Supreme Court ruled in Trop v. Dulles that denaturalization as a penalty for crimes was a violation of the Eighth Amendment’s prohibition of cruel and unusual punishments, with Earl Warren sharing some of Arendt’s sentiments about its horrors: “It is a form of punishment more primitive than torture, for it destroys for the individual the political existence that was centuries in development.”