A reader sent me the following email:

In the article: ‘Do you need to be genius to be genius’ you said
greatness is not an exclusively property of 120+ IQ people. I think it
is. All the great people in the world have 120 or more. Even
subjective iq measurements of those among them whose IQ scores arent
known, have come out to 120 + iq…

I can think of many examples of eminent people who scored below 120 on an IQ type test:

JFK tested at 119

Bill Cosby’s SAT score equated to IQ 84 (though as a child he aced a formal IQ test)

JD Salinger scored IQ 104

Howard Stern’s SAT scores equated to IQ 115

Muhammad Ali’s army test score equated to IQ 85

Condoleeza Rice was told she wasn’t college material based on her PSAT scores (though she aced an IQ test as a toddler)

Rudy Giuliani’s 1073 SAT score likely equated to IQ 119 in his day

 

The problem is, any time you cite these, people immediately call the IQ score into question.  The score is dismissed because the person was tested during childhood, or the test did not measure the cognitive domains the person excels in, or the person wasn’t trying or had a learning disability preventing him from understanding the instructions etc.

In some cases these explanations are valid, but if no amount of evidence can convince you that an accomplished person doesn’t have a 120+ IQ, then  your view is unfalsifiable and thus unscientific.

There are four main reasons people think all accomplished people have 120+ IQs:

They don’t realize how high IQ 120 is

An IQ of 120+ means you’re smarter than 90% of (white) Americans your age.  A young adult who is taller than 90% of white Americans his age is 6’1″+ which is considered a very respectable height and yet an equally rare IQ is considered chopped liver.

They don’t appreciate IQ inflation

Because people  take many IQ tests that often give wildly different scores and then cherry-pick their best scores, an IQ below 120 sounds low to them.  Also, because there are so many elite colleges and high IQ societies accepting scores from so many different tests, it feels like there are so many communities with average IQs above 140, when in reality, many of these groups would regress to the 120s if given a test not used to select them.  Part of what admission tests select for is scoring higher on the admission test than you score on other intelligence tests.

They overvalue intelligence

Intelligence might be the single most important trait, but it’s dwarfed by the totality of other traits.  IQ is probably no more important to most types of success than height is to fighting ability.  On average the best boxers in the world will be well above six feet, but occasionally men of average height will dominate (i.e. Mike Tyson).  Even in fields where height is overwhelmingly important (i.e. basketball), you’ll find the occasional super-short guy (“Muggsy” Bogues), so even at the top of fields as IQ loaded as science, I’d expect a few not-smart people.

They don’t appreciate the bivariate normal distribution

Everyone knows that a super failure can have a super high IQ, but so many deny that a super achiever can have a super low IQ.  But the correlation between IQ and achievement is only meaningful if you believe in the bivariate normal distribution which means that for every high IQ person who is low on achievement, there must be a high achievement person who is low in IQ.

bivariate

Of course these statistical models are just abstractions that are never perfectly observed in nature so things are not quite as symmetrical as the graph implies,  but they’re pretty good approximations.

People have no trouble accepting that height can dramatically overpredict weight and weight can dramatically overpredict height, yet when it comes to IQ and achievement, they think only the former can greatly overpredict the latter and not vice versa.

 

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