Very tricky. Hard to define. IQ vs EQ. And "Law of Averages". For immigration (one of their shared concerns) you can't use the "Law of Averages" ... that the average IQ of a person from Africa is lower than the average IQ of a European. Immigrants should be vetted. Give each immigrant an IQ test, in their primary language, and only let in the high scores. This has traditionally been ...
1. Make it almost impossible to become an immigrant (see France)
2. Don't allow in refugees aka uncritical admittance (see Japan)
3. Have a quota (see US)
4. Preferentially allow in the college educated (see US)
5. Allow doctors and engineers to immigrate in (see US)
Can't help if your country gives up sovereignty, or thinks that refugees have rights to your country.
N American immigration policy is somehow better than the European version. We don't have little countries with their own languages (except Quebec).
Now what is IQ? Partly language, partly culture ... and partly basic intelligence.
What is EQ? Partly sociability, partly mental stability ... and partly personality.
Here is the entrance exam for Cornell University 1891 (in upstate NY). Few here could pass it as an IQ test ...
http://cornellalumnimagazine.com/could-you-have-passed/Almost nobody here could pass an EQ test. Better not immigrate, better stay in quarantine in Outer Slobovia.
While I am pro-immigrant ... I am not pro UN aka that since all people are in the UN, that anyone should be able to immigrate anywhere they like ... same as someone in Texas can immigrate to California.