[Epistemic Status: I suspect that this is at least partially wrong. But I don’t know why yet, and so I figured I’d write it up and let people tell me. First post on Less Wrong, for what that’s worth.]
First thesis: IQ is more akin to a composite measure of performance such as the decathlon than it is to a single characteristic such as height or speed.
Second thesis: When looking at extraordinary performance in any specific field, IQ will usually be highly correlated with success, but it will not fully explain or predict top-end performance, because extraordinary performance in a specific field is a result of extraordinary talent in a sub-category of intelligence (or even a sub-category of a sub-category), rather than truly top-end achievement in the composite metric.
Before we go too far, here are some of the things I’m not arguing:
- IQ is largely immutable (though perhaps not totally immutable).
- IQ is a heritable, polygenic trait.
- IQ is highly correlated with a variety of achievement measures, including academic performance, longevity, wealth, happiness, and health.
- That parenting and schooling matter far less than IQ in predicting performance.
- That IQ matters more than “grit” and “mindset” when explaining performance.
- Most extraordinary performers, from billionaire tech founders to chess prodigies, to writers and artists and musicians, will possess well-above-average IQ.
Here is one area why I’m certain I’m in the minority:
- I believe that Spearman’s G is a reification. At least one smart person has also expressed this opinion, but most experts disagree with him (this ties in with the First Thesis).
Here is the issue where I’m not sure if my opinion is controversial, and thus why I’m writing to get feedback:
- While IQ is almost certainly highly correlated with high-end performance, IQ fails a metric to explain or, more importantly, to predict top-end individual performance (the Second Thesis).
Why IQ Isn’t Like Height
Height is a single, measurable characteristic. Speed over any distance is a single, measurable characteristic. Ability to bench-press is a single, measurable characteristic.
But intelligence is more like the concept of athleticism than it is the concept of height, speed, or the ability to bench-press.
Here is an excerpt from the Slate Star Codex article Talents part 2, Attitude vs. Altitude:
The average eminent theoretical physicist has an IQ of 150-160. The average NBA player has a height of 6’ 7”. Both of these are a little over three standard deviations above their respective mean. Since z-scores are magic and let us compare unlike domains, we conclude that eminent theoretical physicists are about as smart as pro basketball players are tall.
Any time people talk about intelligence, height is a natural sanity check. It’s another strongly heritable polygenic trait which is nevertheless susceptible to environmental influences, and which varies in a normal distribution across the population – but which has yet to accrete the same kind of cloud of confusion around it that IQ has.
All of this is certainly true. But here’s what I’d like to discuss more in depth:
Height is a trait that can be measured in a single stroke. IQ has to be measured by multiple sub-tests.
IQ measures the following sub-components of intelligence:
- Verbal Intelligence
- Mathematical Ability
- Spatial Reasoning Skills
- Visual/Perceptual Skills
- Classification Skills
- Logical Reasoning Skills
- Pattern Recognition Skills
Even though both height and intelligence are polygenic traits, there is a category difference between two.
That’s why I think that athleticism is a better polygenic-trait-comparator to intelligence than height. Obviously, people are born with different degrees of athletic talent. Athleticism can be affected by environmental factors (nutrition, lack of access to athletic facilities, etc.). Athleticism, like intelligence, because it is composed of different sub-variables (speed, agility, coordination – verbal intelligence, mathematical intelligence, spatial reasoning skills), can be measured in a variety of ways. You could measure athleticism with an athlete’s performance in the decathlon, or you could measure it with a series of other tests. Those results would be highly correlated, but not identical. And those results would probably be highly correlated with lots of seemingly unrelated but important physical outcomes.
Measure intelligence with an LSAT vs. IQ test vs. GRE vs. SAT vs. ACT vs. an IQ test from 1900 vs. 1950 vs. 2000 vs. the blink test, and the results will be highly correlated, but again, not identical.
Whether you measure height in centimeters or feet, however, the ranking of the people you measure will be identical no matter how you measure it.
To me, that distinction matters.
I think this athleticism/height distinction explains part (but not all) of the “cloud” surrounding IQ.
Athletic Quotient (“AQ”)
Play along with me for a minute.
Imagine we created a single, composite metric to measure overall athletic ability. Let’s call it AQ, or Athletic Quotient. We could measure AQ just as we measure IQ, with 100 as the median score, and with two standard deviations above at 130 and four standard deviations above at 160.
For the sake of simplicity, let’s measure athletes’ athletic ability with the decathlon. This event is an imperfect test of speed, strength, jumping ability, and endurance.
An Olympic-caliber decathlete could compete at a near-professional level in most sports. But the best decathletes aren’t the people whom we think of when we think of the best athletes in the world. When we think of great athletes, we think of the top performers in one individual discipline, rather than the composite.
When people think of the best athlete in the world, they think of Leo Messi or Lebron James, not Ashton Eaton.
IQ and Genius
Here’s where my ideas might start to get controversial.
I don’t think most of the people we consider geniuses necessarily had otherworldly IQs. People with 200-plus IQs are like Olympic decathletes. They’re amazingly intelligent people who can thrive in any intellectual environment. They’re intellectual heavyweights without specific weaknesses. But those aren’t necessarily the superstars of the intellectual world. The Einsteins, Mozarts, Picassos, or the Magnus Carlsens of the world – they’re great because of domain-specific talent, rather than general intelligence.
Phlogiston and Albert Einstein’s IQ
Check out this article.
The article declares, without evidence, that Einstein had an IQ of 205-225.
The thinking seems to go like this: Most eminent physicists have IQs of around 150-160. Albert Einstein created a paradigm shift in physics (or perhaps multiple such shifts). So he must have had an IQ around 205-225. We’ll just go ahead and retroactively apply that IQ to this man who’s been dead for 65 years and that’ll be great for supporting the idea that IQ and high-end field-specific performance are perfectly correlated.
As an explanation of intelligence, that’s no more helpful than phlogiston in chemistry.
But here’s the thing: It’s easy to ascribe super-high IQs retroactively to highly accomplished dead people, but I have never heard of IQ predicting an individual’s world-best achievement in a specific field. I have never read an article that says, “this kid has an IQ of 220; he’s nearly certain to create a paradigm-shift in physics in 20 years.” There are no Nate Silvers predicting individual achievement based on IQ. IQ does not predict Nobel Prize winners or Fields Medal winners or the next chess #1. A kid with a 220 IQ may get a Ph.D. at age 17 from CalTech, but that doesn’t mean he’s going to be the next Einstein.
Einstein was Einstein because he was an outsider. Because he was intransigent. Because he was creative. Because he was an iconoclast. Because he had the ability to focus. But there is no evidence that he had an IQ over 200. But according to the Isaacson biography at least, there were other pre-eminent physicists who were stronger at math than he was. Of course he was super smart. But there's no evidence he had a super-high IQ (as in, above 200).
We’ve been using IQ as a measure of intelligence for over 100 years and it has never predicted an Einstein, a Musk, or a Carlsen. Who is the best counter-example to this argument? Terence Tao? Without obvious exception, those who have been recognized for early-age IQ are still better known for their achievements as prodigies than their achievements as adults.
Is it unfair to expect that predictive capacity from IQ? Early-age prediction of world-class achievement does happen. Barcelona went and scooped up Leo Messi from the hinterlands of Argentina at age 12 and he went and became Leo Messi. Lebron James was on the cover of Sports Illustrated when he was in high school.
In some fields, predicting world-best performance happens at an early age. But IQ – whatever its other merits – does not seem to serve as an effective mechanism for predicting world-best performance in specific individualized activities.
Magnus Carlsen’s IQ
When I type in Magnus Carlsen’s name into Google, the first thing that autofills (after chess) is “Magnus Carlsen IQ.”
People seem to want to believe that his IQ score can explain why he is the Mozart of chess.
We don’t know what his IQ is, but the instinct people have to try to explain his performance in terms of IQ feels very similar to people’s desire to ascribe an IQ of 225 to Einstein. It’s phlogiston.
Magnus Carlsen probably has a very high IQ. He obviously has well above-average intelligence. Maybe his IQ is 130, 150, or 170 (there's a website called ScoopWhoop that claims, without citation, that it's 190). But however high his IQ, doubtless there are many or at least a few chess players in the world who have higher IQs than he has. But he’s the #1 chess player in the world – not his competitors with higher IQs. And I don’t think the explanation for why he’s so great is his “mindset” or “grit” or anything like that.
It’s because IQ is akin to an intellectual decathlon, whereas chess is a single-event competition. If we dug deep into the sub-components of Carlsen’s IQ (or perhaps the sub-components of the sub-components), we’d probably find some sub-component where he measured off the charts. I’m not saying there’s a “chess gene,” but I suspect that there is a trait that could be measured as a sub-component of intelligence that that is more specific than IQ that would be a greater explanatory variable of his abilities than raw IQ.
Leo Messi isn’t the greatest soccer player in the world because he’s the best overall athlete in the world. He’s the best soccer player in the world because of his agility and quickness in incredibly tight spaces. Because of his amazing coordination in his lower extremities. Because of his ability to change direction with the ball before defenders have time to react. These are all natural talents. But they are only particularly valuable because of the arbitrary constraints in soccer.
Leo Messi is a great natural athlete. If we had a measure of AQ, he’d probably be in the 98th or 99th percentile. But that doesn’t begin to explain his otherworldly soccer-playing talents. He probably could have been a passable high-school point guard at a school of 1000 students. He would have been a well-above-average decathlete (though I doubt he could throw the shot put worth a damn).
But it’s the unique athletic gifts that are particularly well suited to soccer that enabled him to be the best in the world at soccer. So, too, with Magnus Carlsen with chess, Elon Musk with entrepreneurialism, and Albert Einstein with paradigm-shifting physics.
The decathlon won’t predict the next Leo Messi or the next Lebron James. And IQ won’t predict the next Magnus Carlsen, Elon Musk, Picasso, Mozart, or Albert Einstein.
And so we shouldn’t seek it out as an after-the-fact explanation for their success, either.
 Of course, high performance in some fields is probably more closely correlated with IQ than others: physics professor > english professor > tech founder > lawyer > actor > bassist in grunge band. [Note: this footnote is total unfounded speculation]
 The other part is that people don’t like to be defined by traits that they feel they cannot change or improve.
 Let me know if I am missing any famous examples here.