When disaster looms, governments routinely evacuate their citizens.  At minimum, they urge them to leave the danger zone.  They normally supplement this cheap talk with stronger nudges like the Emergency Alert System and official door-to-door warnings.  Governments occasionally even require their citizens to get out of Dodge.

Evacuation policy blends humanitarian and pragmatic motives.  If you care about people, getting them out of harm’s way is common sense.  But even when governments feel little sympathy for disaster victims, they try to evacuate them anyway.  As long as you’re under pressure to “do something” in the face of disaster, it’s vastly cheaper to prevent people from becoming disaster victims than it is to rescue them after they’ve already become disaster victims.  Better still, evacuees foot most of their own rescue bill; the government installs the “Evacuation Route” signs, but the population flees in their own cars with their own gas.  People who stay and lose everything, in contrast, are in no position to practice self-help. 
On reflection, the moral and practical logic of evacuation doesn’t stop at national borders.  (Logic rarely does).  From a humanitarian point of view, letting people leave dangerous countries is only common sense.  The fewer people who experience a disaster, the better.  From a pragmatic point of view, moreover, allowing an anxious foreigner to emigrate at his own expense is far cheaper than bailing him out after tragic events leave him a desperate refugee.  Better for the international community to let people save themselves from minor tragedy than rescue them from major tragedy.

In practice, of course, the world’s governments brutally discourage cross-national evacuation.  Suppose you foresee natural or social disaster for your country.  If you wisely try to get out Dodge, the world’s immigration restrictions dog you at every turn.  Once disaster hits, you might be able to apply for refugee status.  But as we’ve seen, that’s a long shot.  The safe countries may eventually take you in if the mood strikes them.  But it’s an uphill political battle.  Whatever you think about immigration in general, desperate refugees look like a big burden on taxpayers. 

The root problem, of course, is that governments spurn the logic of international evacuation.  Instead of encouraging non-citizens to leave dangerous countries post-haste, they impose deadly bureaucratic delays.  And when a refugee crisis emerges, safe countries are shocked – shocked! – by the horror.  Their complicity – the fact that their own immigration restrictions prevented the refugees from saving themselves back when there was still time – never enters their minds. 

My point, as usual, is that open borders is justice, not charity.  Saving perfect strangers may be a matter of charity.  But letting strangers save themselves with the willing assistance of people other than yourself is a matter a justice