No test measures intelligence. A test only measures you relative to the persons that wrote the test. – loosely quoting Asimov.
2007 is ancient history now. It is an interesting graph that one might correlate with a lack of meritocratic structure in society, but I’m on the low end cause I say this without looking up and reading the study. Pretty pictures evoke emotional blabbering bias and all that.
You don’t know people who are clearly dumb?
The average ACT score for college bound seniors in Florida is 18. The test costs money, which means they’re at least trying. It’s childishly easy. My cat, who is illiterate, can score almost as high (answering at random).
What kind of conversations can you have with folks who can’t do arithmetic or read simple sentences?
I want to stress that Americans, uniquely, are really weird about testing mental ability, probably because of their history of racism. Nevertheless, intelligence is a real phenomenon.
A high IQ doesn’t make you a good person, and it clearly has very little to do with accumulating wealth. But it does make life a hell of a lot easier. It enables you to do second order reasoning and engage in abstract deliberation, which is indispensable for ethics and science. Or do you think it’s a coincidence that average IQs rose 30 points in the last 100 years exactly in tandem with moral progress?