> Haven't we reached the point yet where the whole idea of IQ testing is pretty discredited?
No, the opposite! Throw together any list of questions requiring intellectual ability, on any subjects you choose (making sure to have a wide range of difficulty). Use the list to test a few thousand people selected at random from the same society. Perform principal components analysis (a type of statistical cross correlation) on the answers. The answers will turn out to correlate with a single characteristic of the individual test takers. This common factor is labeled g, general intelligence. There is virtually no sign of multiple intelligences or other factors, just one honking big signal for the g factor.
> And adjusting for IQ, meaning that someone is smart therefore they are expected to earn more money?
There have been large studies of people from the general population, with the scientists measuring every data point they can lay their hands on. It turns out the only factor that significantly affects adult income is IQ. Earned income is almost totally uncorrelated with race, skin color, culture, family wealth, family social rank, location of residence, school system, characteristics of siblings, and so forth. IQ also strongly predicts criminality.
Studies of twins separated at birth show huge IQ correlations between identical twins, but IQ correlations between fraternal twins are no greater than for sibling pairs from different pregnancies. So IQ is mostly inherited, and mostly fixed by the time of conception. In other words, genetic.
No, the opposite! Throw together any list of questions requiring intellectual ability, on any subjects you choose (making sure to have a wide range of difficulty). Use the list to test a few thousand people selected at random from the same society. Perform principal components analysis (a type of statistical cross correlation) on the answers. The answers will turn out to correlate with a single characteristic of the individual test takers. This common factor is labeled g, general intelligence. There is virtually no sign of multiple intelligences or other factors, just one honking big signal for the g factor.
> And adjusting for IQ, meaning that someone is smart therefore they are expected to earn more money?
There have been large studies of people from the general population, with the scientists measuring every data point they can lay their hands on. It turns out the only factor that significantly affects adult income is IQ. Earned income is almost totally uncorrelated with race, skin color, culture, family wealth, family social rank, location of residence, school system, characteristics of siblings, and so forth. IQ also strongly predicts criminality.
Studies of twins separated at birth show huge IQ correlations between identical twins, but IQ correlations between fraternal twins are no greater than for sibling pairs from different pregnancies. So IQ is mostly inherited, and mostly fixed by the time of conception. In other words, genetic.