It is defined and is predictive. For example, educational attainment , job performance, income and wealth. The DOD considers it real enough that all recruits must pass a cogntive screening test, the AFQT, which is like a proxy for measuring IQ.
Somewhat predictive.
> The DOD considers it real enough that all recruits must pass a cogntive screening test, the AFQT, which is like a proxy for measuring IQ.
The DOD also often requires polygraph tests, so not the best endorsement.
William F. Buckley was very intelligent, but so was Gore Vidal.
There are many, many topics where increasing intelligence does not mean increasing convergence of conclusions. The further away you get from hard science, the easier it is to diverge... building (intelligently) upon incorrect and hard-to-falsify foundations.