We’re going to soon talk more about “IQ” and “intelligence”. I’m working on a more in-depth article on the subject to carefully explicate the vast over-certainties I see on “both sides” in the debate. Consider this small post nothing but a throat clearing. I do not answer all questions here.
Because of a recent Twitter battle, it’s clear there are two sides in the debate, which we may call the Sailerons, who follow Steve Sailer and who regularly commit the Deadly Sin of Reification of IQ with intelligence, and the Talebites, who follow Nassim Nicholas Taleb, a group which dismisses IQ scores of being of any real interest.
Briefly and incompletely, here is why I believe IQ is not intelligence. Those who tout IQ never bother to define intelligence except as ability to do well on certain kinds of tests. How do we know these tests measure intelligence? Because those who score high are smart. This is circular. Why this circularity exists and what extra-test definitions of intelligence are, I save for the other article. I do not mean this paragraph as a proof, so no histrionics, please.
The Talebites wave aside test results, saying, for instance, that they’re not especially useful in discerning differences in successful people. This misses that idea that the pool of people who are not a success probably didn’t score well on those tests. Even if IQ properly measures intelligence (which it does in some aspects, but as through a glass darkly), we would expect there to be no correlation of IQ and success at the bottom of professions (among just those people there) and at the top.
This next proposition should be uncontroversial: IQ tests are useful at predicting the ability to answer questions or to complete tasks that are like the questions used in IQ tests. This is almost tautological (leaving out that testing environments are different than real life). An equivalent proposition is: Baking tests are useful at predicting the ability of people to be successful bakers. It is obvious that it takes more than mere baking skills to be a successful baker; that one number is insufficient at describing baking ability. Yet that number will correlate well (in the statistical sense) with other standard measures of success, such as income, and even health.
Now you will hear from the Sailerons that, of course they don’t believe one number can capture all there is to a person’s intelligence. In practice, they violate that commitment routinely, reifying with wild abandon, especially when it comes to differences in populations. Yet I nowhere among the Talebites find the absence of reification, either. Everybody, with rare exception, says people “have” an IQ or that IQ is “real”.
No. Most people do not have an IQ. Only the people who have taken an IQ test have an IQ score: IQ is only a score on a test. All people have intelligence—of varying degree (I reject categorically any hint of Equality or blank-slatism). Intelligence, as I will prove later, and which anyway should have always been obvious, is much more than a test score.
Here, then, is just one small example from an army of examples of how things go wrong when people do not begin with solid foundations. What happened (a multi-cars-on-the-highway-in-the-blizzard wreck) would not have happened if the folks responsible would have begun with a multifaceted, metaphysically sound definition of intelligence. And if they eschewed p-values.
The peer-reviewed paper, published in the International Journal of Epidemiology, by Arden et al. (“authors”), is “The association between intelligence and lifespan is mostly genetic.”
Wow! What a title!
Given my vast cognitive abilities, which are plain to all, but especially to me, I should live forever!
Just look at what is claimed, at least tacitly. At least that the authors have an unambiguous definition of intelligence. A first for this field. And that the same genes which cause big brains also cause long lives. Deep and important.
And silly. The Deadly Sin of Reification has struck. IQ test scores have become intelligence.
Well, so what. So change the title to “The association between IQ scores and lifespan is mostly genetic” and all is fixed. Alas, no. First, because the reification of IQ scores as intelligence is so ingrained, everybody will see “IQ” but believe “intelligence”. Second, and damning, we have wee p-values, outrageous data selection, and shades of the epidemiologist fallacy.
Jay S Kaufman and Carles Muntaner (“critics”) where so aghast at what the authors claimed, they submitted a rebuttal, which is must reading. They did such a marvelous job listing the authors’ many shortcomings and mistakes that there is no reason for me to repeat their words. I shall assume you (yes, even you) are among the minority who will read them.
A couple of highlights. The critics said the authors relied “on null hypothesis significance testing rather than reporting of effect estimates and their imprecision”. The rebuttal by the authors was to say they did not, at least in the abstract (ceding that they did in the paper).
The authors studied twins’ life spans, relying on a bizarre method of data inclusion.
If at least one twin died by the time of the study assessment, then the pair was included in the analysis, but the survival difference could not be calculated if the second twin was still alive, which was true in about half of the pairs analysed. In that case the authors imputed the death date for this surviving twin by using the national average for a person of the same birth year and sex.
Industrial-grade over-certainty there. But it’s even worse. “Moreover, in some instances, the authors found that the person had already reached their life table estimated survival, and so they assigned this person to die in the same year…” Dude. And what about measures of genes themselves and the causal pathways to actual lifetime and actual intelligence, or even just IQ scores? Didn’t happen. More assumptions were inserted for measurement.
Next we need this headline, from a different paper (in New Scientist, the ex-communist magazine, now suitably morphed). “Exclusive: A new test can predict IVF embryos’ risk of having a low IQ.”
Did they say risk of “low IQ”, as if IQ were intelligence and having low intelligence was like having a disease? Yes, sir, they did. Isn’t that sad and stupid? Yes, sir, it is. But it is representative of what happens when you never bother to define intelligence except circularly.
The authors (in the rebuttal) say “Cognitive epidemiology is the field of study that explores links between intelligence, health and mortality.” Health and mortality we can define with only some ambiguity (mortality is certain). But what is their definition of intelligence? IQ. With no idea that IQ is just as well seen as a measure of cultural achievement as intelligence (I mean this only a loose sense; don’t have palpitations). Cultural achievement is, after all, how the questions in IQ tests are picked. (This is not to claim IQ scores have nothing to say about intelligence, suitably defined. And if IQ is predictive, however loosely, with cultural achievement, it is still useful when considering Diversity.)
We can now see why the critics said “To consider IQ, as a marker of a disease or variation in test scores, as a condition to be prevented or treated is absurd.”
There is no more a cognitive epidemiology than there is a memory, perception or emotional epidemiology. These are basic psychological processes, not diseases, therefore not targets of prevention or treatment. A loss of functional cognition, such as occurs in dementia, can be studied as a disease outcome, but variation in intelligence test scores in the population is not such a quantity. Nor is IQ a well-defined exposure even if it were relevant to public health. The misconception of using IQ or other markers of cognitive performance as causes of disease or death, to be prevented or treated at the population level, has had devastating effects in the past century.
As apt and true as that warning is, the hunger for certainty and the mania for measurement assures that we will see many similar mistakes in the future.
CEO of Olive Garden: the average customer eats 5 breadsticks with a standard deviation of 2, which means–
Nassim Taleb: *crashes through the window* YOU IMBECILE. UNLIMITED BREADSTICKS FORM A LEVY STABLE DISTRIBUTION WITH A FAT TAIL. THE VARIANCE IS INFINITE AND IMMEASURABLE.
— Visual Basic for Applications Engineer (@ryxcommar) January 2, 2019