[zippy5]

At quantum scale or near the speed of light newtonian mechanics breaks down, so we know it a local approximation. However, for set circumstances it approximates it does it well. For many decades physists searched universally true theory to no avail.

My point is this, IQ seems to have signal. It probably doesn't hold up in extreme circumstances. Psychology in particular seems to have a difficult time holding large enough studies to find universal constants that we should accept that IQ might be the best local approxination for now.

[Retric]

That doesn’t support your original point. Color blindness is very persistent over time IQ isn’t. Sure +/- 7 IQ points sounds very accurate, but that can be more than a 30 percentile change from two different tests 1 month apart meaning the actual signal is very weak.

You can read papers saying IQ texts on 2 year olds are strongly correlated with adult IQ, but read the details and individual people’s scores varied wildly.

So sure in aggregate it seems consistent, but that’s largely an artifact of test design. Someone with mental handicaps so profound as to be non communicative will consistently score very low, it doesn’t mean much for the general population.