You say X <-->Y? Well what about not-X! What then!

Well, then not-Y, right? Isn't that obvious?

Very odd criticism of my Richwine post from commenter on Brad DeLong's blog:

"Having gone to the link you supplied, I can firmly answer, yes, it seems completely off-base. For example: What If there is positive migrant selection? What if factors others than you mentioned can raise IQ, and those factors are more likely to be present in immigrant families in their new environments? What if statistically the positive or negative effects on countries both sending and receiving are negligible?

Were the populations of countries from which waves of immigrants previously came to the U.S. noticeably smarter and the U.S. population noticeably dumber after these waves?

I can't imagine, Mr. Kuehn, what motivated you to get into this issue from the angle you did. Perhaps you suffered from Blogger's Disease, which is characterized by writing the first thing that pops into your head and then publishing it rather than reconsidering before publication."

If there's positive selection then Latino immigrants ought to have higher IQ than the native white population. Isn't that the obvious conclusion?

If other factors raise IQ then IQ will be raised.

If the effects are negligible then it's negligible.

I'm having a hard time understanding what Fred thinks is off-base. I would guess he agrees that if there is positive migrant selection Latino immigrants will have higher IQs than natives (assuming there's no real racial differences in IQ - which I think is plausible), right? If he thinks that, then what is so off-base about noting that if there is negative selection immigrants will have lower IQs than natives? It's an empirical question at that point.

He asks why I posted it. I posted it because I see a lot of bad reasoning in the critics of Richwine when the criticism ought to be "we should not be so obsessed with IQ or with classifying groups and making immigration policy on the basis of IQ".