Well, apart from the Gulf states – thanks in large part to coming from such a low base that even subcontinental coolies are an improvement over the natives. Otherwise, the cognitive impact of immigration – at least as proxied by the differences in performance on the PISA tests between the national average, which includes immigrant children, versus only native children – is almost entirely negative for its supposed beneficiaries across the entire world. Even those few countries with expressly “cognitively elitist” immigration policies see only the most modest of benefits: Singapore: +0.7; Canada: -0.1; Australia: -0.2. Otherwise, the only countries...