John: Whether we should exclude immigration from certain regions of the world is an excellent question. To put it baldly: Large-scale Muslim immigration is a threat to the receiving society (for the latest, see this), so what should be the response? One possibility is to pick and choose among ethnic or national groups; this is an element of Larry Auster’s “Separationism” and is a view I frequently hear, often from immigration expansionists who just want lots more Mexicans (or Chinese or Irish), but no Arabs. The problem is that this goes against Americans’ basic moral universalism, which I share, and thus is, at the very least, politically untenable. Thus, the other option — reduce immigration overall (for which there are lots of other reasons, too), regardless of nationality. Non-discrimination and mass immigration are just not reconcilable.