My goodness, I never imagined that posting a pointer to an article would cause such a kerfuffle! Dennis Bider doth protest too much, methinks but his protestations are a veritable smorgasbord of fallacious argumentation, so it's worth deconstructing. Let's see, we have...
Flynn is one of those people who helped identify something new and fundamental, and then go on living their lives denying the best explanation because they would like it to be different.
I've long since accepted that you won't be converted to the rational outlook. You are a believer; your spiritual well-being rests on whether a certain hypothesis is right.
Stop trying to persuade everyone how unbiased you are
(I have never tried to persuade anyone that I am unbiased. To the contrary, I have been very up-front about my biases.)
I'm not quite sure how to categorize this one:
People form a hypothesis based on what they would like reality to be; not based on what the naked facts tell them; and so they spend decades trying to find out that group selection for lower populations would favor individual restraint in breeding, only to eventually find out that group selection for lower populations leads to cannibalism victimizing especially young females.
How on earth did we get from the genetics of IQ to cannibalism? Argument by gibberish? Non-sequitur? Maybe I'll just call that one the razzle dazzle.
Here's another one that's challenging to categorize:
The Flynn effect is best explained by heterosis
Even if it were true, just because heterosis is the best currently available explanation doesn't mean it is correct. (Ironically, even Bider himself concedes in the post he links to that heterosis is a hypothesis that has not been adequately tested.) The history of science is rife with examples of "best explanations" that turned out to be wrong.
Bider's second comment is the most colossal straw man I have ever encountered (and that's saying something). I think it says something about Bider's insecurity in his position that he feels the need to not only put words in my mouth but thoughts in my brain and feelings in my heart. This one is particularly ironic:
You are a person who has been cursed with an intolerance for other people's suffering.
because people who actually know me consistently tell me that one of my problems is that I don't empathize enough with those around me.
Did desegregation of schools significantly narrow the black-white educational gap? [No, therefore] so much for environment.
This is another straw man, and a truly offensive one. I have never argued (and would never argue) that exposure to people with white skin is the aspect of the environment most responsible for anyone's academic success or lack thereof.
Don Geddis writes:
First of all, the article you link to doesn't support your summary.
My summary was that Flynn believes that "the evidence supporting the hypothesis that intelligence is primarily genetic is weak." I suppose I should have been more careful to distinguish, as Flynn does, between direct and indirect genetic effects. For example, there is no question that skin color is genetic, so if skin color interacts with some environmental factor (like societal bias) to produce some effect one could say that's a genetic influence. Technically it would be true, but I think that would be a perversion of what people generally mean when they say a trait is genetic. It's certainly not what I mean when I say that the evidence that IQ is genetic is weak, and I'm pretty sure Flynn would agree.
Once you get to average, US, major metropolitan levels of education, nutrition, etc., then the IQ variation due to genetics approaches 100%. It is not the case that the smarter kids were read to more, or went to the museum more often, or watched TV less. It is the case that the smarter kids typically had smarter parents.
If this were really true then that would convince me. But I doubt it's really true. In particular, as I have pointed out before, it is impossible to do a properly controlled study to test the effect of race on IQ because it is impossible to control for the societal bias to skin color. The only way to test the hypothesis is to use two racial groups whose IQ's supposedly differ but whose outward appearance is the same, like jewish and non-Jewish caucasians. (You'd need to have both groups raised in similar cultural circumstances, i.e. either all as Jews or all as non-Jews -- and preferably randomized across both cases.) Until you've done a study like that all you have is more pink flamingos.
Here's another Flynn example that is worth pondering: If on the basis of their genetic inheritance, separated-twin pairs are tall, quick, and athletically inclined, both members are likely to be interested in basketball, practice assiduously, play better, and eventually attract the attention of basketball coaches capable of transforming them into world-class competitors. Other twin pairs, in contrast, endowed with shared genes that predispose them to be shorter and stodgier than average will display little aptitude or enthusiasm for playing basketball and will end up as spectators rather than as players.
The trouble with basketball as an analogy to IQ is that height is an easily observable physical trait that obviously has a causal relationship with potential success as a basketball player. Furthermore, height has both genetic and environmental factors. All this is known and uncontroversial. The trouble is, whether or not externally observable and heritable traits are similarly correlated with intelligence is precisely what is at issue here. So there are no lessons to be drawn from the basketball analogy for the matter at hand (except that it is easy to oversimplify).
Just for the record let me make it clear where I stand. I do not dispute that IQ could be genetic. In fact, I think it almost certainly has some genetic component. The question is how much is genetic and how much is environmental, and, importantly, how much is due to complex interplays between genes and environmental and societal factors, and as long as we're being exhaustive, how much is due to the imprecision and multi-dimensionality of intelligence, and how much is just plain random. My position is merely that the currently available data do not justify the conclusion that direct genetic factors (i.e. the direct transcription of DNA into proteins that build bigger or more effective brains) are the dominant factor. Note that I do not say that this is not the case, merely that the data we have don't justify the conclusion. I will also say, as I have said before, that I do think it would be unfortunate if we did have conclusive data to support this position, and that the human condition would on the whole be the worse for it. And people's eagerness to adopt the conclusion that intelligence is genetic, and to vilify anyone who doesn't join them in their prejudice, even in the absence of conclusive evidence does nothing to dissuade me from this belief.