Suppose we lived in a society split between the following intellectual package deals:
Package #1: Water is wet, so we should drown redheads.
Package #2: Water isn't wet, so we shouldn't drown redheads.
What would happen if a lone voice of common sense emerged to say, "Water is wet, but we shouldn't drown redheads"? No doubt he'd be attacked from both sides. Believers in Package #1 would shake their heads and say, "Once you admit that water is wet, you'd have to be a fool to oppose the drowning of redheads." Believers in Package #2 would say, "Once you admit we shouldn't drown redheads, how can you continue to maintain that water is wet?" Believers in Package #2 might even accuse you of being a troll: "You're feigning sympathy for redheads in order to lure us into the absurd view that water is wet."
This scenario captures the way I felt when Noah Smith tweeted:
I strongly suspect @bryan_caplan of being an opponent of immigration, and his "open borders" thing of being a false flag/satire/troll.
I see where Noah's coming from. Our society is split between the following intellectual package deals:
Package #1: IQ is real, so we should exclude immigrants with below-average IQ.
Package #2: IQ is fake, so we shouldn't exclude immigrants with below-average IQ.
When I talk about ("harp on") IQ research, then, my support for open borders is understandably hard for Package #2 folks to take at face value. At the same time, my support for open borders makes it hard for Package #1 folks to believe that I genuinely grasp the realities of IQ.
As I've argued repeatedly, though, both popular packages are silly - scarcely better than the imaginary packages about the wetness of water and the drowning of redheads. In particular:
1. You don't need an above-average IQ to be a valuable member of society. See here, here, and here for starters.
2. Even if you aren't a valuable member of society, Third World exile is not a morally permissible response. See here, here, and here for starters.