Contradictory statements made by two different professors about IQ scores

[sevensages]

TL;DR Summary

Professor J. Phillippe Rushton says that brain size has a .5 correlation with IQ. Professor David Deutsch says IQ is a matter of knowledge, not hardware. How can I reconcile these two statements?

A few years ago, I watched a video clip on youtube of the late Professor J. Phillippe Rushton on the Donahue Talk Show in 1990. Professor Rushton was a professor of Psychology of a large university in Canada. The talk show host Phil Donahue (kind of sarcastically, in my opinion) asked J. Phillippe Rushton "So are you saying that a larger brain means a smarter brain?"

Professor Rushton responded "Yes. Brain size has about a 50% correlation with IQ."

Then a few days ago, I was reading Sam Harris' book Making Sense: Conversations on Consciousness, Morality, and the Future of Humanity. In Making Sense, Sam Harris includes a transcript of his conversation with the Professor David Deutsch. The book Making Sense says the following introduction to Professor David Deutsch: "David Deutsch is a visiting professor of physics at the Center for Quantum Computation at the Clarendon Laboratory of Oxford University, where he works on the Quantum Theory of Computation, and Constructor Theory."

In David Deutsch's conversation with Sam Harris in Making Sense, Deutsch said the following: "The fear of super intelligent machines entails the same mistake as thinking that IQ is a matter of hardware. IQ is just knowledge of a certain type."

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Now IQ has to be a matter of hardware to some degree because a person cannot think without a brain. But maybe Deutsch is correct that IQ is [largely] just knowledge of a certain type. But doesn't Rushton's statement that brain size has a 50% correlation with IQ contradict Deutsch's statement that IQ is just knowledge of a certain type, not hardware?

Whether or not IQ is only a matter of hardware is definitely a question of psychology. So Rushton, being a professor of Psychology, was certainly an expert on this, not a talking head.

I don't know whether or not David Deutsch is an expert on this or not. Normally, I would think that a professor of physics would just be a talking head on topics of psychology, but the details in Harris' introduction to Deutsch make me think that maybe Deutsch's specialty is in the physics of the brain. Harris wrote that Deutsch works on the Quantum Theory of Computation. Is the Quantum Theory of Computation a theory of how the human brain does computation? Harris questions Deutsch about topics of Psychology extensively.

How can I reconcile Rushton's statement that brain size has a 50% correlation with IQ with Deutsch's statement that IQ is only a matter of knowledge of a certain type and not a matter of brain hardware?

If there is no way to reconcile the two statements, who is correct, Rushton or Deutsch?

 

[BillTre]

I would expect IQ to have a 1.0 correlation with IQ.

IQ is not well defined anyway.

 

[sevensages]

I would expect IQ to have a 1.0 correlation with IQ.

IQ is not well defined anyway.

Of course IQ has a 1.0 correlation with IQ. Duh. Are you trolling?

The consensus among psychologists (the experts in this topic) is that IQ is well-defined.

The question is: does IQ have a correlation with brain size? That question has implications on whether or not Deutsch's statement that IQ is not a matter of hardware is correct or not.

 

[BillTre]

Of course IQ has a 1.0 correlation with IQ. Duh. Are you trolling?

You wrote it not me.
Check what you write before posting.

 

[Frabjous]

I believe that the modern correlation value is around 0.3-0.4. This means that SOME of intelligence variability is attributable to brain size.
I believe that Deutsch is trying to make a different point. It is always hard to tell with interviews.

 

[sevensages]

You wrote it not me.
Check what you write before posting.

I only wrote it to quote you. Did mean to write something different than what you actually wrote in your first post on this thread? If so, please clarify.

 

[BillTre]

I only wrote it to quote you. Did mean to write something different than what you actually wrote in your first post on this thread? If so, please clarify.

Your TL;DR Summary says "Professor J. Phillippe Rushton says IQ has a .5 correlation with IQ" in your first post.
Self awareness can have benefits.

 

[sevensages]

I believe that the modern correlation value is around 0.3-0.4. This means that SOME of intelligence variability is attributable to brain size.

To me, your statement seems to contradict Deutsch as well.

I believe that Deutsch is trying to make a different point. It is always hard to tell with interviews.

Do you mean that you think Deutsch is trying to make a point that does not necessarily contradict the assertion that brain size has a significant correlation with IQ?

I think that MAYBE Deutsch is trying to make a point that does not contradict Rushton, but I don't know what that point is exactly.

If Deutsch is trying to make a different point, I don't know exactly what his point is.

It sure seems to me like Rushton is right, not Deutsch.

 

[sevensages]

Your TL;DR Summary says "Professor J. Phillippe Rushton says IQ has a .5 correlation with IQ" in your first post.
Self awareness can have benefits.

You're right. I apologize for asking you if you were trolling. I would not have asked you if you were trolling if I knew the TL;DR summary originally said that Rushton says that IQ has a 0.5 correlation with IQ.


In the TL;DR summary, I meant "Rushton says that BRAIN SIZE has a 0.5 correlation with IQ. Deutsch says that IQ is a matter of knowledge of a certain type, not hardware. How do i reconcile these two statements?"


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Now that that is all cleared up. Please comment on the question of the OP.

P.S. I found out how to edit the TL;DR summary. And I edited the TL;DR summary.

 

[sevensages]

I have edited the TL;DR summary to say that Rushton says that brain size has a 0.5 correlation with IQ. So now let's please focus on reconciling Deutsch's statement with Rushton's statement, not my typo.

 

[Rive]

The consensus among psychologists (the experts in this topic) is that IQ is well-defined

IQ is what their IQ tests measure.

Kind of well defined, yet not really...

You need to find the scientific statements to have the chance for a scientific reconciliation between seemingly opposing statements. Interviews does not really has the right impact.

 

[sevensages]

IQ is what their IQ tests measure.

Kind of well defined, yet not really...

You need to find the scientific statements to have the chance for a scientific reconciliation between seemingly opposing statements. Interviews does not really has the right impact.

Well, Sam Harris' interview with David Deutsch is all I have. So we're going to have to just work with that interview alone. It is not ideal, but it's all we have

 

[Rive]

If so, then you might as well ask for our educated opinions right away.
You may get answers at comparable level to interviews.

 

[sevensages]

If so, then you might as well ask for our educated opinions right away.
You may get answers at comparable level to interviews.

I asked for everyone's educated opinions in the OP of this thread. That's fairly "right away" in my opinion.

 

[Rive]

Well, by my opinion that long winded opening post kind of made it into an incitement of pit fight between prof interviews.

It could help a lot if you would clarify the direction of your curiosity (in the first post too).

 

[phinds]

Deutsch says that IQ is a matter of knowledge of a certain type

It has always been my understanding that IQ is an imperfect measure of intelligence, and that it has nothing to do with knowledge.

I think to get any other conclusion, you would have to define "intelligence" VERY precisely.

 

[sevensages]

Well, by my opinion that long winded opening post kind of made it into an incitement of pit fight between prof interviews.

It could help a lot if you would clarify the direction of your curiosity (in the first post too).

The OP gave the two professors' credentials on this matter.

The direction of my curiosity is to determine if IQ is only a matter of knowledge like Deutsch says it is.

 

[sevensages]

It has always been my understanding that IQ is an imperfect measure of intelligence, and that it has nothing to do with knowledge.

I think to get any other conclusion, you would have to define "intelligence" VERY precisely.

That's always been my understanding as well.

But now Deutsch is saying otherwise.

And even though IQ is an imperfect measure of intelligence, I still think IQ tests are useful and valid. No tests are perfect.

 

[Frabjous]

To me, your statement seems to contradict Deutsch as well.



Do you mean that you think Deutsch is trying to make a point that does not necessarily contradict the assertion that brain size has a significant correlation with IQ?

I think that MAYBE Deutsch is trying to make a point that does not contradict Rushton, but I don't know what that point is exactly.

If Deutsch is trying to make a different point, I don't know exactly what his point is.

It sure seems to me like Rushton is right, not Deutsch.

Intelligence is complicated. Rushton is talking about the human brain. Deutsch is talking about artificial systems. Their comments should be interpreted in the light that there is only partial overlap between the two topics.

 

[Vanadium 50]

o we're going to have to just work with that interview alone. I

What you mean "we", kemosabe?

We don't have to do anything. You're the one who asked us for help, and you're the one who got on our case for pointing out a mistake you made. You might consider if you would make more progress if you toned it down a notch.

A television interview is not a good source. It's got all the problems of a popular book, and its shorter. Because the discussion was many decades ago, you might have to go to a library to find the source material.

I am a non-expert, but 0.5 seems too high to me. First, it is not true across species. Elephants, for example, have bigger brains than people, but don't go around composing symphonies. Second, two different IQ tests correlate to maybe 0.85 at best. In light of that, 0.5 is a surprisingly large number.

 

[Tom.G]

Perhaps substituting "Problem Solving Ability" for "IQ" would work.

 

[pinball1970]

And even though IQ is an imperfect measure of intelligence, I still think IQ tests are useful and valid. No tests are perfect.

If this is something that is interesting to you, a literature search on intelligence and IQ could be a start.
Brain case volume and intelligence could be another.

Our brain cases certainly got bigger over Evolutionary time.

I have looked into the IQ thing just on its own and it is a little nebulous. Check out Feynman's result.

EDIT: Quick look seems to say "weak" correlation.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7440690/

 

[pinball1970]

That's always been my understanding as well.

But now Deutsch is saying otherwise.

And even though IQ is an imperfect measure of intelligence, I still think IQ tests are useful and valid. No tests are perfect.

Did you get anywhere on your search?

 

[berkeman]

Thread closed temporarily for Moderation...

 

[berkeman]

@sevensages -- As has been pointed out probably a few hundred times before on PF, IQ scores are an imperfect measure of intellectual ability:

https://en.wikipedia.org/wiki/Intelligence_quotient

Scores from intelligence tests are estimates of intelligence. Unlike, for example, distance and mass, a concrete measure of intelligence cannot be achieved given the abstract nature of the concept of "intelligence".[7] IQ scores have been shown to be associated with such factors as nutrition,[8][9][10] parental socioeconomic status,[11][12] morbidity and mortality,[13][14] parental social status,[15] and perinatal environment.[16] While the heritability of IQ has been investigated for nearly a century, there is still debate about the significance of heritability estimates[17][18] and the mechanisms of inheritance.[19]

IQ scores are used for educational placement, assessment of intellectual ability, and evaluating job applicants. In research contexts, they have been studied as predictors of job performance[20] and income.[21] They are also used to study distributions of psychometric intelligence in populations and the correlations between it and other variables. Raw scores on IQ tests for many populations have been rising at an average rate that scales to three IQ points per decade since the early 20th century, a phenomenon called the Flynn effect. Investigation of different patterns of increases in subtest scores can also inform current research on human intelligence.

Please refrain from referencing IQ scores (especially in the PF technical forums) in your future thread starts. Thank you, and the thread will remain closed.