I have noticed over the past decade or so that many anarchists have made opposition to national borders into their flagship issue. The reason for this is obvious. National borders demarcate the territory of national states, which are historically rooted in conquest and plunder. Plus, many anarchists associate immigration controls with racism (which has often been the case), another flagship issue for many anarchists. However, this leads to a theoretical problem. The abolition of states would result in more rather than less “borders” (for example, the Central American countries are small and have their own borders, but the USA is a massive territory where the central government imposed “open borders” internally between the 50 states). Of course, it’s possible for relatively small political units to have open borders between them (see the Schengen area), but the opposition to “borders” has actually led many anarchists to embrace political centralization (see here) even if they retain “anarchism” as a remote, abstract ideal. The logical outcome of such a theoretical position is to embrace a global state that imposes “open borders” everywhere (which would really amount to global house arrest). We see plenty of anarchists using such logic in other areas, with examples being Noam “I’d like to see the power of the federal government increased” Chomsky or Goofy “I’m thankful we have a world empire” Gillis.
Of course, the rejoinder is typically along the lines of “anarchism is not just mere anti-statism, anti-centralism, voluntaryism…” but that anarchists must also oppose market exchange, hierarchy, technology, industrialization, civilization, the laundry list of Isms/Archies/Phobia, exclusion, hegemonic interpersonal relations, religion, violence, microaggressions, adultism, and any number of other things, which range from the serious to the plausible to the absurd. However, anti-statism, decentralism, voluntaryism, free association, etc are certainly necessary prerequisites for anarchism, just as it is necessary to master algebra before moving on to infinitesimal calculus.