1. IQ is a bourgeois artifice devised to justify class stratification. It does not measure anything objective - it merely creates a number that is then used to deny some people access to resources. There is nothing more to it than that.
2. When it comes to real cognitive capacity - Kahneman had it right, there are two cognitive systems at work: intuitive (what he calls System 1) and deductive (System 2). Each one has its advantages and disadvantages, and they are supposed to complement each other. To what extent they do, depends on social environment. Some environments encourage checks and balances of these two systems, other discourage it. As the article nicely points it out, capitalist corporations often fall into the second category. I would add the academia to the list. But the main point is that "stupidity" is socially constructed -by which I mean that it is social environment that discourages the optimal coordination of intuitive and deductive thinking.
While we are on the subject of measuring or rather mismeasuring humanity - there is a recent proliferation of various indices that are supposed measure good things in life - from "impact" (whatever that is), to efficiency, to quality of life, to enabling environment and the like. What strikes me about the great majority of these indices is that they are modern versions of IQ - they do not measure anything objective, they merely generate numbers that stratify different societies on a neoliberal hierarchy of values. These indices have plenty of items purporting to measure "freedom", "equal opportunities" "rule of law" and similar neoliberal abstractions but fall rather short of items measuring labor conditions (from safety, to adequate compensation, to collective bargaining, to legal protections from exploitation) that is of primary importance to the overwhelming majority of the population outside the academia and policy think tanks.
The ubiquity of these exercises proves it once again that the so called social "sciences" are for the most part nothing more than journalism and ideology providing needed conclusions to those in a position to pay for them. It is basically a form of mental pollution that should be ignored by anyone interested in finding what is conventionally referred to as truth.
-- Wojtek
"An anarchist is a neoliberal without money."