> I don’t really know any 70 year olds who are “all there.”
You are almost certainly wrong, but it's also possible that your thereness measurement scale is still calibrated to the briefest and least knowledgeable period of your life.
"But global IQ is an amalgam of different kinds of intelligence, the most popularly studied being fluid intelligence and crystallized intelligence which together—along with abilities called working memory and processing speed—are combined to yield global or Full Scale IQ. Fluid intelligence or fluid reasoning (abbreviated Gf) reflects the ability to solve novel problems, the kind that aren’t taught in school, whereas Crystallized intelligence or crystallized knowledge (Gc) measures learning and problem solving that are related to schooling and acculturation. And they have very different aging curves.
Gc averages 98 at ages 20-24, rises to 101 by ages 35-44, before declining to 100 (ages 45-54), then 98 (55-64), then 96 (65-69), then 93 (70-74), and 88 (75+).
The decline with age in Gf—solving novel problems—is even more precipitous. Gf peaks at ages 20-24 (100), drops gradually to 99 (25-34) and 96 (35-44) before starting a roller coaster plunge to 91 (45-54), 86 (55-64), 83 (65-69), 79 (70-74), and 72 (75+).
These values are just averages for the entire US population of adults, with the mean IQs for each age higher for more educated individuals. But the same rate of decline across the age range seems to occur for all adults, on average, whether they are semi-skilled workers or university professors. "
When it comes to solving novel problems, the population of 81 year olds is more than two standard deviations worse than the population of 22 year olds. Alternately, the average 81 year old is poorer at solving novel problems than 95% of 22 year olds, and the average (100-IQ) 22 year old is better at solving problems than 95% of 81 year olds; I am including the 22 year olds that you rarely meet because they are silo'd off in a special needs caretaking system.
There is an EXTREMELY PRONOUNCED decline of global IQ with age LONG before dementia, that it is almost completely verboten to admit exists because it combines our fear of our own mortality with our fear of a corporeal self with our fear of being alone with our fear of being useless with the minimum baseline of respect for our elders. Nobody wants to say, or be forced to admit, "I am not as smart or capable as the man I used to be," and many of us would rather eat a bullet or put our fist through someone's face, but it is true nonetheless. By the time any of us have the authority to start forming conventional wisdom (eg, writing textbooks, or doing interview shows, or helping our children raise our grandchildren), this story is not one we want to tell others or ourselves, and so most people cannot accept it.
Sure, but how relevant or predictive of performance is IQ for the "being president" task beyond some functional baseline?
The user interface for a president to influence the operation of a country is people and relationships. The president doesn't need to solve novel problems, they need to select the right people to identify, prioritise and solve problems (occasionally novel but probably mostly boring and universal human problems), bounded by political constraints.
I guess there is also a major performance element to the role, where "thinking on feet" is very important. Probably something like "IQ" is very helpful with that.
Politician is an interesting role because it's selected primarily by emotions rather than how a large corporation would go about selecting an executive officer.
That being said, I really hope we'd all agree a high IQ president would be favorable to a low IQ president.
Basically you’re calling me young and dumb, charitably. You don’t know how old I am.
I know that I was far more capable when I was younger. I have gained wisdom but that wisdom wouldn’t help me if I was fighting jet lag on a global diplomatic mission aboard Air Force One.
I know that my retired parents who are still intelligent shouldn’t work a day job. They can barely operate Google Maps let alone be commander and chief to the most technologically advanced military in the world. And they’re about 10 years younger than Joe Biden.
You are almost certainly wrong, but it's also possible that your thereness measurement scale is still calibrated to the briefest and least knowledgeable period of your life.
I intend this charitably.