MARK KRIKORIAN: Debating Open Borders at Reason. On Bryan Caplan: “His argument was that treating foreigners in any way differently from Americans was invidious discrimination, morally identical to ‘mandatory discrimination against blacks, women, or Jews.’ He seemed to confine his comments to employment, but if not allowing a foreigner to take a job in the United States is morally impermissible, then isn’t denying him the vote also impermissible? If welfare programs exist, how can he be barred merely because he came here last week?”

This sounds like a good debate tactic for use against Caplan and those who agree with him — good ol’ reductio ad absurdum.