There is a "positive manifold" of results across test we call "intelligence tests", this is a property of the test data. What "IQ" does is take the mean of this and call it a property -- no such property exists.

Consider athleticism: across all sporting activites there's a positive correlation of ability. Call it "athleticism". But people do not have "athleticism". If you break there leg some of these correlations disappear, and some survive. Atheticism is a result of a very large number of properties of people, which arises out of highly complex interactions.

Heritability measures the correlation of traits with genes. We have ~20k genes, and we share 90% with mice, almost no genes code for traits. The vast majority of trait-gene correlations are caused by geographical (and cultural) mating patterns. So scottish accents are nearly 100% heritable, since nearly all people with one share some genes; and nearly all people without one do not have at least some of these genes. So much for "heritability" -- the use of this statistic, outside of extremely narrow biological experiments where corrlation is the result of causing genes to corrlete (by design) -- is pseudoscience.

And so 1) there is no trait "intelligence"; and 2) all claims to trait-intelligence-gene correlation are confounded by massive non-genetic factors beyond causal control.

And so: psychometrics is pseudoscience. The vast majority of its popular results are by frauds, charlatans and just plain idiots. I have no pleasant words for them: I call them by their name. Fraud is rampent, and even if it weren't, given causal-physiological semantics to factor correlations is pseudoscience.

It wasnt very hard to see, many of the citations in these famous works of IQ research were conducted under extreme causal confounders (eg., black people in aprethid south africa, people selected for the IQ test by an IQ test, etc.).

There isnt any kind of scientific research which can today establish "IQ" as a property of people --- we have no experiments which can control for known, massive, confounders. We cannot breed generations of people with deterministic genetic variation, deterministic childhoods, (etc. etc.). This kind of science is as impossible today as microbiology was to the greeks.

If you're willing to agree "IQ" is in the same realm "Athleticism" in terms of realism and heritability, then I have nothing more to say. There would be no question studying IQ is incredibly valuable.

Sure, maybe there is no part of the human which is the IQ, and it's a merely a summary of other factors being expressed. I don't think IQ researchers ever claimed otherwise.

Are you familiar with "entropy"? Isn't that a statistical summary of a configuration of atoms? Wow! Emergent properties, with no physical existence are a big part of science.