Nature vs. Nurture: "Rationality"

==Pro’s Case==R1:Pro argues that the education system has declined, and that now, environments are too stimulating. While I think that our education system isn’t actually declining, but just declining relative to other countries, it is irrelevant. Surely, we can agree that whatever the overall state of education in the United States, it is good in some schools and bad in others. And yet, twin studies find that shared environment—which would include which school your parents send you—doesn’t matter that much. If schools were important, then family environment would certainly matter, because it affects what school you’re sent to. Same with how “stimulating” an environment is—surely, some family environments in the U.S. are more or less stimulating than others. Pro concedes my explanation of the Flynn effect—and while this shows that environmental influences used to have a significant impact, they no longer do, which is why the Flynn effect has stopped. R2: Pro argues that people with a genetically higher IQ might seek out environments that raise their IQ even further—presumably educational resources. But if this were the case, surely shared environment would have a closer relationship with IQ. Shared environment includes what school a person goes to, what opportunities their parents provide for them—and this appears to have very little effect. For twins, their IQs are correlated at .86 when they’re raised together, compared to .76 raised apart. It’s plausible that these factors Pro mentions are responsible for that .1 difference. High IQ twins raised together might both benefit from their parents sending them to a good school, while twins raised apart might be sent to different educational environments. But if such things were more important than genetics, it would show up in shared environment—being self-directed toward education isn’t the only way your education is affected, your parents play an important role. If ‘study habits’ were relevant, then shared environment would be relevant—parents have a significant effect on study habits.I do not ignore Pro’s evidence about high IQ variance during childhood—I merely point out that such changes are temporary. If a stimulating environment raises your IQ as a child, then it goes back down once you’re an adult.Exercise and meditation may help people, but showing that isn’t enough—Pro have to also show that the effect is significant relative to the effect of genes.Pro cites an article about a study showing that brain training tasks can improve fluid intelligence, but this study has been debunked. It only used 1 test of fluid intelligence, and the control and experimental groups were different in an important way—the experimental group had to come in regularly for training, while the control group just went home and did whatever in between tests. [1] The experimental group may have had more motivation than the control group. A new study, using the same brain-training techniques, but with 8 intelligence tests and better controls, found no evidence that this brain training has any effect. [2] R3:The higher IQs explain the other things Pro mentions—IQ is associated with all of those things. If one group had a genetically higher IQ than the other, then there’s no evidence that the intervention had any effect.The Norwegian study does show that education can have an effect, but I don’t think it shows a permanent effect. The measure was done 3 years after the schooling ended—the gains could have faded out since then. This is supported by the fact that people reach their peak intelligence at 26, not 19. [3] If schooling was a relevant causal factor, it would have also shown up in twin and adoption studies. The quality of schooling in America is very different depending on where you live—and yet, adopted siblings aren’t more similar to each other in IQ than any 2 random people, and twins raised together aren’t much more similar than twins raised apart. R4:Again, I concede that IQ may change quite a bit because of environment during childhood. But then it goes back to your genetic potential and stays there. Con’s evidence does not contradict this—in fact, it supports my conclusion. My theory would expect childhood intelligence to be different from adult intelligence, because the effects of family environment fade out.==My Case==C1: Since we haven’t found all of the genes responsible for intelligence, it would be impossible to find out exactly how much IQ is genetically determined using the kind of study Pro cites. That’s why we use twin studies. Pro fails to provide a substantive criticism of twin studies—saying correlation is not causation is not enough, you have to provide a more plausible theory of causation that explains the correlation. Surely IQ doesn’t cause genes—but what explains the correlation then, if not that genes cause IQ?C2:No, it shows that conscientiousness is more influenced by ‘something other than genes/family environment’ than genes. This is not necessarily environment.C3:I am not asking Pro to argue for “only one type of environment.” He can cite any environmental influence he wants—as long as it’s actually an environmental influence. I would like Pro to cite a definition of ‘environment’ that includes the choices of the person in question.A school (or parents) instilling values in the child that makes them more conscientious—teaching responsibility, for example. This is an environmental influence. A person choosing to save money rather than spend it as soon as they get it? This is not an environmental influence—and yet, it would be included under ‘unique environment’ because ‘unique environment' simply means ‘not genes or family environment.’ Identical twins raised in the exact same environment could still make different choices—have different levels of conscientiousness. For IQ, this doesn’t really apply, but conscientiousness is just how responsible and self-disciplined someone is—something people can choose to change regardless of their genes or environment.[1] http://www.smartplanet.com...[2] http://scottbarrykaufman.com...[3] McArdle, John J.; Ferrer-Caja, Emilio; Hamagami, Fumiaki; Woodcock, Richard W. (2002). "Comparative longitudinal structural analyses of the growth and decline of multiple intellectual abilities over the life span.". Developmental Psychology 38 (1): 115–42.