Sam Harris and the Myth of Perfectly Rational Thought

[Jim__]

66. No, you're misstating the issue.

From post #64:

At issue is whether or not there is any genetic component to IQ, so it’s not as if there’s any middle ground.

No, that's not the issue. I'm not sure there is any biologist or psychologist who denies that there is a genetic component to intelligence.

From the Turkheimer article:

Intelligence is heritable. To say that intelligence is heritable means that, in general, people who are more similar genetically are also more similar in their IQ. Identical twins, who share all their DNA, have more similar IQs than fraternal twins or siblings, who only share half. Half-siblings’ IQs are even less similar than that; cousins, still less.

Heritability is not unique to IQ; in fact, virtually all differences among individual human beings are somewhat heritable. Pairs of identical twins are more likely to be similar not only in height and weight and skin color compared with fraternal twins, but also in their marital status, their political views, and TV-watching habits.

Murray takes the heritability of intelligence as evidence that it is an essential inborn quality, passed in the genes from parents to children with little modification by environmental factors. This interpretation is much too strong — a gross oversimplification. Heritability is not a special property of certain traits that have turned out to be genetic; it is a description of the human condition, according to which we are born with certain biological realities that play out in complex ways in concert with environmental factors, and are affected by chance events throughout our lives.

Heritability is not unique to IQ. Turkheimer et al are not denying that there is a genetic component to IQ.

The issue they are taking is:

...

Genetic group differences in IQ. On the basis of the above premises, Murray casually concludes that group differences in IQ are genetically based. But what of the actual evidence on the question? Murray makes a rhetorical move that is commonly deployed by people supporting his point of view: They stake out the claim that at least some of the difference between racial groups is genetic, and challenge us to defend the claim that none, absolutely zero, of it is. They know that science is not designed for proving absolute negatives, but we will go this far: There is currently no reason at all to think that any significant portion of the IQ differences among socially defined racial groups is genetic in origin.

...

As to whether it’s not as if there’s any middle ground, I refer you back to my post #29. Five premises are listed as Murray's. A middle ground is accepting any or all of the first 4 premises and rejecting premise 5

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From post #64:

As far as Harris diving into the controversy, that was pretty much his whole point. At some level there has to be discussion with those who may be diametrically opposed politically.

Whether or not group differences in IQ are genetically based is not a political question. If Harris's point was to dive into the controversy, Turkheimer et al presented him with an excellent opportunity. He failed to join the debate at any substantive level.

Notice the similarity between the claim that you made in post #64:

At issue is whether or not there is any genetic component to IQ, so it’s not as if there’s any middle ground.

And the description in the Turkheimer article about Murray's rhetorical move:

... Murray makes a rhetorical move that is commonly deployed by people supporting his point of view: They stake out the claim that at least some of the difference between racial groups is genetic, and challenge us to defend the claim that none, absolutely zero, of it is. ...

Murray's challenge is not actually pertinent to the debate.