If the concept of intelligence were nonsense, no test that claimed to measure intelligence would predict anything.
??? Of course it would. That's the entire point of some of the commentary from Jensen that you posted.
Let's take a step back here. One of the central issues with IQ testing is that the evidence for it is correlational. IQ correlates with exam scores, with interview scores, and with various cultural success factors such as income and social class. The battery of tests contained within IQ, when combined, correlated strongly with these criteria. Now there are two possible explanations for this.
The first is that there is a real thing, called g, that IQ tests measure. This actual biochemical value then directly effects the various performance characteristics that are associated with it.
The second is there is no real thing, called, g, that IQ tests measure. Instead g is an abstraction made up of various different measures. Intelligence isn't a thing, it's just the average of the performance on a variety of related cognitive tests.
Through the kinds of correlational studies that IQ researchers use, you can't prove you're looking at one or the other.
So when you ask:
Are you now suggesting that intelligence does not exist?
I'm not sure what you're asking. Jensen and others have been quite vocal in arguing that it doesn't matter whether intelligence exists (is a thing, is reified) or not. It's manifestly not true that intelligence has to be an actual thing, has to actually exist, to be a reliable indicator of future performance. IQ tests could just be an abstract average of a basket of related abilities, function perfectly well as an approximate measure of performance on those abilities, and g, or general intelligence, would not exist at all.
If you have a cloud of points on a graph, and you draw a line of best fit through those points, to show the correlation, that doesn't in itself show that there is a hidden factor that controls all the other results that is represented by the line.
I don't understand what on earth you mean by the shoe size analogy. Your last sentence is incomprehensible.
The last few words should have been 'about whether it's valid.
The point being made is that there are many things in life that are strongly and reliably associated with each other. The shoe size of a child is very strongly correlated with the distance between the Moon and the Earth, because both increase over time. The moon drifts (very slowly) further away from the earth, and child's feet (quite quickly) grow in size. That doesn't mean the two are causally related in any way.
I'm sorry, what do the test conditions of a particular intelligence test (there are very specific rules about how they are administered) have to do with 'culture'?
Culture is just 'the way things are done around here'. Formal testing in an exam hall or similar is not normal for everyone, and people who are used to the cultural set up of a formal test environment may do better than those that aren't.
It strongly suggests you're not that familiar with these effects, since you seem to be assuming that practice effects would hit a cealing by retaking the same test.
On the WAIS-IV, it does.
No, it doesn't. 'Practice effects' is a term referring to wide variety of factors known to influence cognitive testing, from familiarity with the equipment through to boredom with the task, of which immediately retaking the same test is merely one.
People who come up with these issues are not exercising their imaginations - these are well-established problems around experimental design in cognitive psychology, that scientists spend years learning about and trying to control. That's why you can't just decide that because you've taken a few elementary precautions any effect you discover must be something fundamental to the human condition. The science doesn't work that way, and is known not to work that way.
Who said anything about 'fundamental' to the human condition? Are you talking about intelligence (which certainly is fundamental), or the Black-White IQ score gap?
I'm talking about IQ tests, and the claim that they measure something called g (general intelligence). The Bell Curve relies on the idea that IQ testing measures something fundamental to the human condition, whether that is g or something similar to g. IQ testing in general, does not.