From Vox:

Shutting down immigration won’t solve Europe’s terrorism problem

Updated by Amanda Taub on March 22, 2016, 4:09 p.m. ET @amandataub [email protected]

There's still much we don't know about Tuesday's terror attacks in the Belgian capital of Brussels, but one thing seems inevitable: There will be renewed calls for crackdowns on refugees and migrants in Europe and for limiting Syrian or even Muslim immigration here in the US.

… Such calls speak to deep, intuitive fears that many of us feel in the wake of an attack like this one. Terrorism, especially when linked to groups like ISIS, seems like a threat that comes from the outside. So it’s natural to conclude that if we could just keep dangerous outsiders from getting into our countries, we would be safe.

Natural, but wrong.

Europe’s terrorist threat, while rising, has come overwhelmingly not from foreigners but from fellow Europeans. And terrorism experts say it’s Europeans who’ve traveled to fight with ISIS and are now coming home, not refugees or migrants, who pose the real threat.

Closing borders and cracking down on refugees won’t make us safer, because that’s simply not where the problem comes from …

Okay … but the fact that many European terrorists are second or third generation Muslims suggests that continuing to import more Muslims into Europe in the future will make Europeans even less safe through the end of this century.

In general, moderns have a hard time grasping Will Rogers’ basic point that if you find yourself in a hole, the first thing to do is to stop digging.