I agree that IQ tests measure something.
But is it intelligence? Intelligence tends to be defined in practice as what is measured by IQ tests, as good an example of circular reasoning as I can think of.
FWIW, I signed up for Mensa some years ago. Took two IQ tests, and they came back with an over 40 point difference. Turned out the higher one was a test where the tester read a long complex essay about an obscure subject, in this case priests of the classical Greek (pagan) religion, and then I answered a lot of questions about the subject.
I guess I aced that one. What nobody asked me about was my reading habits. I’d read a book on the subject about a week before and could probably have gotten about the same IQ score if they hadn’t read me the essay!
BTW, attending Mensa meetings will do a dandy job of convincing a person that if IQ measure intelligence there are a lot of stupid intelligent people out there, or at least at Mensa meetings!
It’s not so much a case of circular reasoning as it is a matter of definition: intelligence is defined as whatever it is that IQ tests measure. But, (in the article) you can see that there are a bunch of things that correlate (and that anti-correlate) with IQ, that seem not directly related to whatever it is that IQ tests measure.