I am very pleased that the new Bryan Caplan and Zach Weinersmith open borders graphic novel has hit #1 on The Washington Post non-fiction bestseller list. I am also pleased to see Garett Jones examine the idea in a new short paper, here is part of his critique:
I use the same constant returns to scale framework as Caplan, in which the migration of every human being to the United States would increase global output per capita by about 80%. I then estimate that in the benchmark model, where IQ’s social return is much larger than its private return, the per-capita income of current U.S.residents would permanently fall by about 40%. This is not an arithmetic fallacy: this is the average causal effect of Open Borders on the incomes of ex-ante Americans. This income decline occurs because cognitive skills matter mostly through externalities: because your nation’s IQ matters so much more than your own, as I claim in 2015’s Hive Mind. Therefore, a decline in a nation’s set of average cognitive skills will tend to reduce the productivity of the nation’s ex-ante citizens.
I will be sure to link to Bryan’s reply when it comes.