Does Improvability of IQ Mean Intelligence Can Be Equalized?

Evidence presented throughout the previous articles demonstrates that IQ can improve via environmental interventions, with the Flynn effect serving as a century-long illustration that enhanced environments can elevate IQ scores. Consequently, some observers believe that since IQ is changeable, intelligence can be equalized. However, while improving IQ scores is achievable, making everyone's intelligence identical is an entirely different proposition.

A dramatic example occurred in post-World War II Warsaw, where Soviet-backed authorities rebuilt the devastated city according to communist ideals. They created uniform neighborhoods with similar buildings, evenly distributed services, and mixed occupational groups in every area. After thirty years of this intensive egalitarian planning, researchers tested a large sample of children. The results showed that equalizing neighborhood environments did nothing to eliminate the positive relationship between IQ and parental occupational prestige or education. The association persisted in a form typical of traditional societies.

The Polish study revealed that similar living conditions and uniform education were unable to eliminate IQ differences or the correlation between parental socioeconomic status and child IQ. This massive environmental intervention accomplished little in equalizing intelligence, suggesting skepticism is warranted regarding the ability of social programs in democratic nations to equalize intelligence.

Perhaps equalizing intelligence is overly ambitious. Some intervention designers pursue the more modest goal of reducing IQ differences by improving environments. Evidence suggests this goal has merit. Preschool programs have reduced differences in math and reading skills, and educational policies targeting struggling students decrease overall variability.

Providing more positive environments to those in unfavorable circumstances does reduce population-wide intelligence inequality. However, giving interventions to the entire population typically doesn't eliminate intelligence differences because individuals in both high and low IQ groups experience improvements. Thus, the most effective way to reduce intelligence differences is providing beneficial treatment to low-performing individuals while withholding it from high-performing individuals.

Intelligence inequality persists because of one fundamental fact: IQ scores are partially influenced by genes, as indicated by heritability values above zero. Environmental interventions don't equalize intelligence because genetic influences remain. Modifying educational programs, improving family socioeconomic status, or making neighborhoods uniform won't equalize intelligence because genetic variation continues to cause some intelligence differences.

If all environments were equalized, variability would decrease somewhat. However, this reduction is minimal when heritability is high. In populations with heritability of .80 (typical among adults in wealthy countries), eliminating environmental differences would only decrease IQ variability by 10.6%. With heritability of .50, the reduction would be 29.3%.

Crucially, improving environments for everyone differs from removing environmental differences. General environmental improvements can raise average IQ without affecting the relative importance of genetic and environmental factors. Equalizing environments must increase heritability because genetic and environmental influences must total 100%. Paradoxically, improved environments may amplify the importance of genetic differences—the opposite of what many environment-improvers intend.

While intelligence improvability doesn't imply equalizability, non-equalizability doesn't mean non-improvability. Since feasible options for equalizing IQ are likely ineffective, fretting about eradicating individual differences is futile. A superior goal is improving people's lives—sometimes resulting in higher IQ scores, sometimes not.

Nevertheless, realistic understanding of what's probably possible matters. As Scarr and Weinberg noted, decades of naive environmentalism have trapped many into wrong-headed assumptions about human malleability, leading to unrealistic promises. The fallacy is believing equality of opportunity produces outcome sameness. While equality of opportunity is laudable, outcome sameness is biologically impossible. Despite society's best efforts, IQ inequality will occur, and misrepresenting intelligence differences and their malleability only creates disappointment.





From Chapter 17 of "In the Know: Debunking 35 Myths About Human Intelligence" by Dr. Russell Warne (2020)