IQ, Genes, Global Warming, and Prediction Markets

I view the blogosphere as a hyper-efficient idea-evaluating machine. As time passes, the ideas passing through this machine should become more refined. The good ideas should come to the forefront with the bad ones sinking to the murky depths. The discussion surrounding these ideas should become more intelligent. In my view this is what has happened over the past six years. The conversation is at a much higher level today than in the blogosphere's infancy.

I've been impressed with the discussion following James Watson's comments. People are writing about a difficult topic without calling each other names. Okay, maybe that isn't exactly true, but the fact that they're talking about it at all is impressive. A big part of the reason the discussion got off the ground is that some big names like Andrew Sullivan, Cato, and Will Saletan were brave enough to comment. Kudos to them.

The best commentary I've seen that's skeptical of the genetic explanation of racial IQ differences is from Jim Manzi at The American Scene. As he writes, the two ways to evalute the genetic hypothesis are to 1) find the mechanism that links genotype to phenotype or 2) what he calls the "econometric" technique, which basically means "do a controlled study" without necessarily knowing the mechanism behind any relationship that emerges.

The science behind the mechanistic approach is still too much in its infancy to provide any answers. The econometric approach is what most of the discussion has centered around. Manzi concludes with,

Historically, researchers first began investigating the potential genetic basis of racial disparities in IQ scores by evaluating whether “degrees” of racial membership corresponded with degrees of IQ difference. This work led to no compelling results. In more recent decades, researchers have analyzed various natural experiments relevant to this question. The most famous of these is the Minnesota Transracial Adoption Study in which various high-IQ white parents adopted biologically black, white and mixed race children. In theory, this should allow us to isolate the genetic influence on intelligence by evaluating the IQs of each group of children after they have all been raised in (approximately) equal environments. In fact, as opposing interpretations (pivoting on the potential confounding of age-of-adoption with racial group) demonstrate, it actually provides a good illustration of why it is so difficult to segregate genetic from environmental effects accurately by racial group – no natural experiment is sufficiently controlled to do this. Given our current datasets and analytical tools, when we use econometric methods to try to understand the causes of group differences in intelligence, we are like cavemen trying to figure out how a computer works by poking at it with sharpened sticks.

I sympathize with this point of view. It's very difficult to have true controls in sociological studies. Yet, the data from the MTAS are compelling to me, even after accounting for the shortcomings. The control group nullifies most of the confounding factors (environment) even if it doesn't completely isolate the independent variable (race).

If we similarly hold as skeptical a standard as Manzi's in other areas of science, we wouldn't be able to say much of anything on a lot of topics. As an example, I've argued in the past that the only way to truly prove that global warming is a man-made phenomenon is to have two Earths that are alike in every way except one has humans on it and the other does not, and then measure temperatures over time. That would be a truly controlled study. Of course, that's impossible so scientists have to use mechanistic techniques to make their best possible evaluations based on the available data. I don't know Manzi's views on global warming, but given his skepticism toward ever having appropriate controls in adoption studies, I would think he'd be even more skeptical about the possibility of ever proving anthropogenic global warming. Controls in adoptions studies are imperfect; a control to prove global warming is impossible.

I agree with Steve Sailer who in the GNXP comment thread linking to Manzi's post argues,

With any empirical question, all you can do is play the odds.

Personally, I've never been wholly convinced that the racial gaps in IQ have a genetic component (there's always the Flynn Effect to complicate matters). But I'd definitely offer five to one odds that at least half of the one standard deviation (15 point) black-white gap will turn out to be hereditary. I'd probably go as high as offering ten to one, but not, at present, to one hundred to one.

There are degrees of skepticism, degrees of plausibility. In the end, there's rarely ever a sure thing in questions like these. We deal in probabilities.

Wait a minute.... Did someone just say, "play the odds"? It's too bad there aren't prediction markets thriving today. I imagine a time in the future when anytime a blogosphere pundit makes an assertion about a controversial topic, he puts his money where his mouth is and bets a few bucks on his views. Next to the timestamp of his post, there would be a dollar amount linked to an online prediction market confirming the wager. The bloggers not willing to bet could be ignored. The signal-to-noise ratio in such a blogosphere would be far, far higher. "We'll fact-check your ass!" was just the beginning. As the blogosphere continues its evolution, the appropriate phrase will become, "We'll check your sorry ass's prediction market returns!"

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Causality and AGW


Thanks for the detailed and thoughtful comments on my article.

Actually I've written a lot about exactly this question vis-a-vis global warming. I wrote the cover story in National Review this summer that argued for accepting the reality of global wamring and moving on to policies for reducing risks.

I agree, and have argued extensively, that attribution of warming to causal drivers in the temperature record is not reliable for exactly the reason that you indicate. The irreducible fact, however, is that CO2 can be demonstrated in reproducible expermiments to be a GHG (that is, it absorbs and redirects infrared radiation, but not shorter-wavelength radiation). This is a direct analog of the missing "physical mechanism" in the IQ-Race-Genes debate.

The big open question for AGW that this does not resolve is the impact of feedbacks, and all of my work on this topic has really been to try to think through the implications of this uncertainty for policy.

You can see a lot of this at The American Scene.


Jim Manzi


Semi-agreement here: