# Do IQ tests measure intelligence?

Okay, I am kind of skeptical about IQ tests. I think they only measures the speed of a person's reasoning abilities as well as a small portion of knowledge (or just knowledge). I kind of think that any person is capable of solving any problem by just having the main/neccessary knowledge of the problem. For example, in a question like this:

if x = 5 and y = 5. What is the value of x when multiplied by y?

The example above can only be answered if one knows what the word "multiplied" means. As you can see, that actually test your verbal and mathematical knowledge, it doesn't actually measures your intelligence.

Now assuming that one knows what the word "multiplied" means. One should be able to solve the problem, and it would just be a matter of time, in other words it would be a matter of how quick my reasoning abilities operate.

Disclaimer: I am not a philosopher, nor do I have a huge amount of knowledge in the subject. And I really hope I made sense.

• 1) There are people who know what multiplied means and still cannot solve that question, what about them? 2) what exactly do you use for a definition of intelligence?
– user2953
May 6, 2013 at 7:02
• This isn't a philosophy question as phrased, as far as I can tell. If you want to learn about IQ tests and what scores on them correlate with, and what various tests intend to and/or do measure, just read Wikipedia. Pay particular attention to g (or read the separate article on it). May 6, 2013 at 11:03
• @NeilMeyer That is not even remotely true. Claims about bias are hotly disputed; the existing evidence for bias ranges from weak to risible; and when efforts are undertaken to remove the purported sources of bias, it either doesn't change the results that were supposed to be the result of that "bias" or amplifies them. You can easily see this by going anywhere that these topics are commonly discussed, and seeing what people have to say about Raven's Progressive Matrices. If you can find a "bias" in those tests I have absolutely no idea what to tell you. Sep 18, 2022 at 10:08
• "It in no ways allows for any development difficulties that may lead to a false result and in no means test for the social skills that are crucial to many professions. It is at best a test for basic problem solving abilities." Well, yes; "basic problem solving abilities" are at the core of the concept of "intelligence", and "social skills" have nothing to do with that concept, so of course we should expect tests intended to measure "intelligence" to take interest in the former and ignore the latter. Understanding how this applies to "developmental difficulties" is left as an exercise. Sep 18, 2022 at 10:11
• @user48488 The "theory of multiple intelligences" is pseudoscience, and also in no way undermines the validity of IQ tests, which is one of the most replicated findings in psychology. Dec 7, 2023 at 1:49

The problem is that 'intelligence' is pretty much a recognise-it-when-you-see-it kind of attribute; as you say, there are plenty of indicators of intelligence that are highly culture-specific, and even fairly culture-neutral tests are very succeptible to scores increasing with practice.

So in one sense IQ tests (which are very varied, and range from tests of verbal reasoning through 'pick the successor' non-verbal tests through interviews with psychologists) only measure how good one is at performing that specific test. But a lot of effort is expended in trying to ensure that 'being good at this test' correlates as highly as possible with what we'd recognise as 'intelligence' generally. It's a specific instance of the general problem of measuring a fuzzily-defined feature.

So yes, you're right to be skeptical; IQ tests generally produce widely divergent scores (at two different tests in the same sitting I scored 124 and 161) and give a false perception of authority (to the extent that they are used in employment and academic selection processes); it's probably true that you're better off directly testing the skills you require than assuming IQ tests give you what you want. But you should also be aware that, while you think you might have a good notion of what 'intelligence' is, it's an extremely hard concept to pin down in any way more reliable than what IQ tests give.

• Thanks for the insight. I know intelligence is a hard concept but was referring to it as the general/everage view of it(the skilled use of reason). May 6, 2013 at 20:35
• " only measure how good one is at performing that specific test. " This is simply not true, and it is propaganda repeated by the critics. We know that Spearman's g is real because we can see how performance at "that specific test" correlates strongly with performance at all the other "specific tests", even when there is no reason why they ought to simply considering the actual test material. "at two different tests in the same sitting I scored 124 and 161" Those would be sub-scores for different types of reasoning; that doesn't refute the overall concept. Sep 18, 2022 at 10:17
• I know I must sound unreasonably put out by this. The reason is that there is a classic motte and bailey argument deployed here, wherein "IQ scores for a person might vary by several points in various test conditions" is the motte, and "the entire concept of intelligence is incoherent, and only promoted to invent a justification for racism" is the bailey. Yes, I have had to engage with this argument multiple times over multiple years. No, I am not misrepresenting anyone's opinion in the slightest. I bend over backwards to give them a chance to clarify. Sep 18, 2022 at 10:19

Of course the answer to whether IQ test measure intelligence depends on your definition of intelligence. (And on how the test-taker is feeling on the day of the test.)

But psychologists have broken down intelligence into various types of intelligence, and devised specific tests to measure specific types of mental abilities. It turns out, using a statistical technique called "factor analysis", that all different types of intelligence measures are positively correlated with IQ scores, some more than others, but all to a significant degree.

IQ tests certainly measure something, and that is correlated in populations with what we usually think of as signs of intelligence; academic and socioeconomic success.

If IQ tests did not measure any aspect of intelligence, then surely there's no such thing as e.g. "working memory". How could a measure of working memory like the digit span test, even if it is not a very reliable measure, not be correlated with "intelligence"? That does not mean that "intelligence" is only measured by IQ tests, which is either absurd or vacuous. However, "intelligence" presumably does involve cognitive powers, like Short Term Memory.

Personally, I'd like an "intelligence" test to reliably test memory, short and long term, and then add something more qualitative or person centered. Comprehension, facility, etc., at what the subject is best at. So a combination of IQ and 'multiple intelligences'.

• "multiple intelligences" are a sham theory promoted by people who want to wedge in concepts like "physical intelligence" and "emotional intelligence" so that they can claim that people who are unusually sympathetic to the feelings of others, or who have good proprioception and balance, belong in the same category as those who solve difficult conceptual problems and thus enable technological progress. The core concept is not that hard to understand, and we don't have to invent our own weighting for memory/recall/etc. Please read e.g. en.wikipedia.org/wiki/G_factor_(psychometrics). Sep 18, 2022 at 10:23

I would say personally it all depends on the test, though that is just a guess as I have only taken one. I assume one could make a fairly accurate IQ test, but even then you would only be testing for certain elements of intelligence.

For example of the WAIS test that I took, I do not think it was a fair measure of a persons reasoning skills at all. Some of the methods used where in comparing words and asking how they were similar. I have a problem with this not because of what is being tested, but how it was tested at least for myself. It was clear the instructor was looking for one specific relation between the two words, and they didn't give a clear meaning of what they were looking for. They never said if they wanted an abstract or a direct comparison. So when asked I just threw answers out there, and what I saw was the instructor waiting til I gave one specific example. Which I think is bullshit. If a person can give you hundreds of comparisons, and someone else can only think of one; Yet the one they think of is the comparison you are looking for then the person who could only think of one would get a higher score. Which I think is just plan silly. This was how it was for any word analysis on the test. While the instructor didn't pick up on it, I was watching her very carefully. I was monitoring her actions to be sure how she was testing me.

There was also the issue with each category that was tested for being only tested for individually. We know the Corpus Collasum is responsible for the interaction between the two hemisphers of the brain. A person can have strengths in this area, so shouldn't we also do tests which rely on multiple categories to get an indication of how they put everything together?

Another complain was how knowledge was integrated into the test. While I do know Crystalline intelligence is based on knowledge I do think it is based on wither you know a particular word. I think it is based on the amount of knowledge you have stored in your head to refer back to. So when you just test for a persons understanding of certain words you are being bias. A kid who has studied physics and math, biology, and various other aspects. Yet did not study literature might have a lot more information to refer back to, than one who just studied literature. The test however would give different results. Which again I just think is silly. In honest regarding testing of knowledge, I think you should test for as many words as possible. You should test for a persons understanding of the word, not just their ability to give you one definition. Can they describe how it functions, can they describe certain aspects of it? This wasn't tested for. I also think if something isn't know it should be stricken from the test, and the category should be measure the same way, as if the person had answered all questions. We would then have to have difference confidence levels for each person taking the test, but I think it would be more accurate. Though I need to do more research to be sure, as others have said intelligence is not simple at all.

I am going to stop now, I could right a full length article on the problems with test. Which considering my grammar and sentence structure is poor would be a bad idea. The point is I did not think the test accurate. And I must acknowledge that I can't know for certain if I would have done better or worse had it been more accurate, as all those aspects that impair it's accuracy would effect other test takers as well. I think where these tests shine is pointing out if someone is mentally handicapped or not. That would be something I feel the processing speed and working memory categories could to some degree measure accurately. Though focus can also impact those scores, so even then it wouldn't be perfect, but it would be alright I think.

At the end of the day it doesn't really matter too much anyways. I say aim for the stars, try and go as far as you can. If you don't make it well at least you tried. May an IQ test be accurate at measuring intelligence? Some of them likely are, but even so what matters is can you do what you want to do. If you want to be a physicist or a philosopher will an IQ test tell you that you are cut out for it? I don't think so, what will is actually trying to go into a field and seeing how well you perform.

IQ tests measure intelligence, if we circularly redefine intelligence to mean an IQ test score or rating.

Alfred Binet, the originator of IQ tests, devised them only to help show which school children needed tutoring. Other psychologists soon made the tests into a societal medusa which set intelligence in stone; low scores were employed to justify educational neglect or worse.

Higher scores would glorify the status quo. In the 1920s psychologists Catherine Cox Miles and Lewis Terman, published a list of 300 posthumous IQ scores of historically eminent people. Since Binet tests couldn't be given to the dead, Cox and Terman's test consisted of various points and scaled ratings being applied to biographical details. The study circulated in the popular press for decades, and it is still sometimes taken at face value online even in 2020.

• This is a terrible argument. "Test results were interpreted by a certain group in a certain way, and thus used to enact policies that had a harmful effect" is not even remotely related to the question of whether the test measures the thing it claims to measure, nor to the question of what that thing actually is. Sep 18, 2022 at 10:27
• @KarlKnechtel, Here it's not necessary to know what the thing "actually" is, it's enough that a representative set of given famous instances are insufficient evidence towards various claims. Examples: the arbitrary inefficacy of Witch Trial tests do not oblige critics to provide a comprehensive theory of withcraft; unsupportive statistical metastudies collating various randomized controlled trials of a medical therapy do not require a statistician have an expert understanding of that therapy's underlying theory...
– agc
Dec 7, 2022 at 6:43
• Binet's tests accurately determine which school children need tutoring and which are gifted. They also conclusively demonstrate that those concepts are coherent. The concept of intelligence is extremely well understood in the relevant academic fields, and it takes an act of willful ignorance to pretend that this is a matter of circular reasoning, to bring up witchcraft (?!?!?), etc. I am absolutely mind-boggled that you would stick to your logically fallacious reasoning and double down on it two years later when it's pointed out. Dec 10, 2022 at 12:32
• @KarlKnechtel Can you point to a reference that provides a definition of intelligence? Apr 17, 2023 at 18:18

No, of course not. Intelligence is much more complex and subtle than that. Why should one be able to reduce it to a number? But of course we make judgements about people - we say someone is intelligent, cunning, witty, charismatic etc. So one could say we are simply quantifying this.

The essential problem of IQ is that its specific to a certain Western Culture; and specific to a certain nexus of skills within that - that is scientific. The tests usually measure geometrical, verbal, numerical and logical reasoning. So, yes; it does measure intelligence - the intelligence of men and women within the scientific subculture of Western civilisation: One would not expect the Bushmen of the Kalahari to do well. Nor the Pequeno of Amazon who do not have much use for numbers. This is not because that they lack intelligence.

But even then it has problems - for example, it has no predictive value. I very much doubt if one had access to the IQs of Nobel Prize winners that they will be especially high. They are just high enough. Richard Feynman, Nobel Prize winner in Physics had an IQ of 125. Much higher than that shows that one is simply a virtosi in doing well in IQ tests and probably a bore - not that one is a potential Nobel-Prize winning Physicist or Biologist.

A much more interesting question would be track why and how IQ tests have been used. What this says about the role of reason, the intellect and the kind of skills being measured in that society.

• IQ has extremely good predictive value for academic success, for life earnings, for life expectancy, for life satisfaction etc. No, it cannot predict Nobel Prize winners, but that's probably because there are many other factors that are needed for that than having a high IQ.
– JonB
May 25, 2020 at 14:37
• "its specific to a certain Western Culture" No it isn't. "within the scientific subculture of Western civilisation" No it isn't. Lots of unsubstantiated and false assertions in this non-answer. Sep 19, 2022 at 4:24
• @MoziburUllah Something being discovered by Westerners does not make it "specific to a certain Western Culture". That's a patently silly non sequitur. Are general relativity, quantum mechanics, organic chemistry, etc. "specific to a certain Western Culture"? Of course not. Sep 28, 2022 at 18:02
• "pseudo-science would actually be more accurate" False. IQ has been shown to be a good predictor of life expectancy, income, educational achievement (1, 2, 3), crime, etc. Sep 28, 2022 at 18:04
• "That's how Richard Feynman saw it" Irrelevant. And he didn't say that. "his IQ was only slightly above average" 124 is not "slightly above average". Also, the average IQ of physicists has been measured to be significantly higher that of the general population. Sep 28, 2022 at 18:07

Douglas Murray is a modern exemplar of how simplistic framing of IQ is problematic. He and Sam Harris defending his views, show a real lack of critical thinking about terms and methodology around intelligence. They are still reacting like they can't see any problem with what they've been saying, despite very widespread criticism.

IQ is quite good for measuring impairment, eg. from poor nutrition, cognitive damage etc. However it's very problematic at quantifying high 'intelligence', because of general problems with the tails of distributions, and dispute about what high intelligence is. Murray glosses over high IQ people who have unsuccessful lives, saying because they are clever they choose a wide range of lifestyles, which just side-steps the weak correlation at the extreme. One of Murray's arguments for the validity of IQ as measure of intelligence is it's correlation with earnings. But what about the lack of correlation at the high end of IQ, with deep insight, or significant intellectual achievements?

There's a really interesting paper: A dynamical model of general intelligence: the positive manifold of intelligence by mutualism. This outlines how we should think of intelligence as like the health of an ecosystem. We might take the concrete measurable 'biomass' as a proxy for abstract 'health of ecosystem', analogously to taking IQ as proxy for intelligence. It would be good at picking up the main kinds of unhealthy ecosystems: where there are few niches, few biological strategies active. But it would rate some kinds of unhealthy fragile & unresilient ecosystems very highly - like where algae has choked out everything else, or where a small number of species (strategies, equivalent to types of mental algorithm in this analogy) dominate. Truly healthy resilient ecologies are diverse, self-stabilising, have many niches and a wide range of strategies - usually including ones unique to that ecosystem, but also often convergently evolved strategies.

So not just biomass but biodiversity compares to true intelligence, while IQ only captures the equivalent of the former, in terms of the capacity to solve unique problems rather than just a narrow set used as proxies for all (practicing IQ tests improves scores, so does motivation like rewards for doing well & local cultural regard for high scores). Generating fittedness of a species to a niche, requires an ecology that developed against the right mix of stability & challenge to result in the most effective creatures/insights/algorithms. Equivalent to a good varied challenging but supportive learning environment during an individuals development.

Growing up in a house with at least 80 books has lasting impacts. Not only plentiful resources though, but also challenge are required to develop a resilient ecosystem: it's interesting to note success in competitive debating is a better predictor of career success than IQ or grades across a wide range of jobs and in management, but having such debate clubs has typically been limited to elite schools. Cultural priorities and values affect developmental environments.

If there were no consequences to accepting a simplistic definition of intelligence fine, leave the details for academia. But there are many problems, especially denying people's ability to grow and flourish and develop their intelligence by essentialising it as fixed - this is captured with ideas around the benefits of a growth mindset, where research has shown attitude is more important than IQ for many tasks.

It seems obvious also, that extreme intelligence requires a culture of respect for it, and special dispensations toward odd people for communities to fully benefit - and modern society is typically bad at that, and historically has failed to recognise a problem.

I'm thinking of the mathematician Ramanujan who had a cultural framework and support to totally dedicate himself to mathematics, as a form of religious devotion. Or Einstein (who's developmental language delay could see him diagnosed as on the autistic-spectrum now) as coming from a Jewish heritage, where rich families considering it a religious service to marry exceptional scholars into their family, despite lack of fiscal prospects (see the focus of the modern Haredi community on prioritising full-time religious scholarship for men over paid work). Intelligence occurs within a social ecology, as well as being manifested through a kind of personal mental ecology. And we would benefit more as a society through valuing neurodiversity, the equivalent of biodiversity, than by valuing a narrow picture of the mechanism and function of intelligence.

Essentialising people as having fundamental unchanging differences is intrinsically problematic, it goes against have a growth-mindset, and acts contrary to intersubjectivity which supports intelligence (discussed here: How would you apply John Rawls "Theory of justice" to everyday decisions?). Being good at putting ourselves into the mindset of others is the basis for most uniquely human intelligence, and picturing minds as fixed undermines that.

IQ is good at picking up people who underperform, usually because of developmental problems. And for picking up population change - the Flynn Effect is thought to be principally linked to improved diets and more highly enriched environments. But the human genome is far narrower than most species, because of repeated population bottle-necks. And intelligence has been useful in every environment. But, we evolved our intelligence focused primarily on our complex social environment (see the Dunbar Number linking neocortex size in apes to social group size), and that may be changing.

There is evidence autism-spectrum conditions are increasing. Children on the spectrum are substantially more likely to have parents who are engineers, accountants, in medicine or science ("risk of having a child with ASD was almost two times greater for mothers in highly technical occupations" from here), and similar correlations between having close family on the spectrum & success in STEM fields. This may indicate a trend of our species reallocating our intelligence from primarily social challenges, towards prioritising technologically useful skills. So not so much increasing intelligence in technological societies, but repurposing it. And, IQ clearly values technologically useful intelligence over social (I linked the change in values to almost abandonment in modern philosophy of considering wisdom here Wisdom and John Vervaeke's awakening from the meaning crises?). That is the result of a cultural judgement on what intelligence is useful.

Inter-group variation in IQ is almost invariably far smaller than in-group variation (given good nutrition & other base-line factors like not growing up in a war zone). While IQ weakly correlates with earnings, I suggest a society's success has a lot more to do with the occasional person of exceptional insight than it does to population averages. And the success of people like that, depends crucially on being in societies that support neurodiversity - I'd argue over millennia, Sephardi Jewish communities and Hindu communities have been better at valuing these (eg early Buddhism had over 10,000 sutras all memorised not written, and special sirnames permanently honoured families with an exceptional scholar of the Vedas). Valuing and supporting unusual minds, is what we should prioritise culturally, not IQ.

The computer coding world is leading the way in this, and their practices and adaptations should be learned from for schools, other employment sectors, and society as a whole. Biologist Robert Sapolsky has interesting ideas on the origins of OCD & schizotypy disorders as extreme cases of mindsets that have historically benefitted societies. Intelligence is a landscape to be explored, not an unambiguous direction. And we should pay attention to positively shaping the landscape in so far as we can, rather than pushing people in one direction through it.

What is intelligence?

Are Life and Intelligence analogous?

Free Will and Intelligence

Are levels of intelligence different levels of consciousness?

AI singularity, and the transmission of intelligence

• "They are still reacting like they can't see any problem with what they've been saying, despite very widespread criticism." This is the correct response when one has evaluated the criticism and deemed it nonsensical. "But what about the lack of correlation at the high end of IQ, with deep insight, or significant intellectual achievements?" This argument belies a fundamental statistical misconception; please read e.g. lesswrong.com/posts/dC7mP5nSwvpL65Qu5/why-the-tails-come-apart . Overall, I find this answer long and rambling, and begs the question of how you define intelligence. Sep 18, 2022 at 9:56
• This is a common pattern I have noticed among critics of IQ research - they claim to refute the findings, but then do not actually properly engage with the findings, instead diving into value claims (often while insinuating moral or ethical fault on the part of the researchers). Even if backed up with a proper chain of consequentialist reasoning, saying that society would be better off if we thought about intelligence differently or valued mental traits differently, is not actually addressing the claim that an IQ test can, indeed, measure something of consequence. Sep 18, 2022 at 9:59
• "creative intelligence" is a misuse of English by people who want (usually for political or culture-war reasons) to treat creativity as if it belonged in the same natural category as spatial reasoning and pattern matching (it does not, except insofar as it enables those abilities). This "permanent unchangeable Essence" bit is, quite simply, a strawman. However, IQ measurements at one point in a person's life are expected to correct with IQ measurements later in life - because it is the same physical brain doing the cogitation required by the test. Sep 18, 2022 at 11:00
• " Saying the proxy that IQ measures is intelligence" This is just playing semantic games. IQ measures intelligence; it does not do so perfectly, both because the concept is not well enough defined to admit perfect measurement (but it is still clearly a coherent concept; see e.g. Spearman's g) and because measuring it requires a human's cooperation (by analogy: weight is objective; physical strength is variable, and measuring it requires the participant to exert a consistent effort, and then you have to argue about how to incorporate fatigue into your definition). Sep 18, 2022 at 11:27
• "creative intelligence" - is still a misuse of language; if you mean creativity, say creativity. "Intelligence has meant different things in different places because it has been different things in different places" No; it has been understood in different ways in different places - because it is understood by humans, who are not very good at defining words and who have learned things about cognition over time. Sep 18, 2022 at 11:28