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Cited by 60Cognitive Abilities and TestingRace, Genetics, and SocietyIntergenerational and Educational Inequality Studies

What if the hereditarian hypothesis is true?

Gottfredson, Linda S.·2005·Psychology, Public Policy, and Law
DOI 10.1037/1076-8971.11.2.311
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Abstract

Rushton and Jensen (this issue) make a strong empirical case that the long-standing, worldwide Black-White average differences in cognitive ability are more plausibly explained by their “hereditarian ” (50% genetic causation) theory than by “culture-only ” (0 % genetic causation) theory. This commentary also examines whether their data warrant the implications they draw for public policy, and whether critics are correct that sometimes it is better to tell untruths than truths.

AI snapshot

Written from the paper’s full text.

TL;DR

Gottfredson evaluates Rushton and Jensen's (2005) case that the worldwide Black–White IQ gap is substantially (50%) genetic, judging their evidence more plausible than culture-only theory and arguing that the direct tests of the hereditarian hypothesis most need replication. She concludes the truth may lie closer to 70–80% genetic and that candor, rather than "benevolent lies," better serves policy and race relations.

Key findings

  • Gottfredson argues the five evidentiary prerequisites for the hereditarian hypothesis are met: same-race IQ differences are real, functionally important, and substantially genetic, and between-race mean IQ differences reflect real, functionally important differences on the same *g* factor.
  • She reports that nationally representative 20th-century data show no narrowing of the IQ gap, with standardized effect sizes of 1.0 ± 0.2 for children and adults across all ages and decades, averaging 1.02 across 20 samples.
  • NAEP Black–White achievement gaps narrowed from 1.07 SD in the 1970s to 0.89 in the 1990s, but this is within the range *g* theory predicts (maximum 1.20 SD; minimum 0.80 ± 0.04 SD), with narrowing of 25% in reading (1.06–0.79), 20% in math (1.07–0.87), and 15% in science (1.22–1.04).
  • She states the evidence is "so consistent and so quantitatively uniform" that the genetic contribution may be closer to 70–80%, the within-race adult heritability in the West, and that the burden of proof has shifted to culture-only proponents.
  • She notes major life outcomes are moderately heritable (earnings ~40–50%, occupation ~50%, education ~60–70%), with half to two thirds of that heritability joint with *g* (studies limited to European Whites).

Methods

This is a commentary, not an empirical study. It evaluates Rushton and Jensen's (2005) review of 10 bodies of evidence against scientific and moral criteria, assessing replication and consilience of *g*-based hereditarian versus culture-only theory. It also draws on Gottfredson's own analyses (in press) of 20th-century IQ data and the 1971–1999 NAEP Trend Series.

Limitations

The paper states that the most direct tests of the hypothesis—transracial adoption, racial admixture, and behavior genetic modeling of mean group differences—have been "uncommon or fraught with ambiguity" and clearly need replication, and that being politically sensitive they are least likely to be replicated; it also notes anomalous findings (e.g., Raven Matrices training in some South African samples) requiring replication and the Flynn effect as a paradox for both theories. Evident from the text: the brain-correlate studies are "mostly with Whites," and the heritability estimates for life outcomes are "limited so far to European Whites," so generalization to other groups is untested.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1037/1076-8971.11.2.311

Cites

59 of 59 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 49 cited sources checked · 0 supported · 0 flagged

  • Findingcitation
    § Replication · p. 4

    Evidence contradicts the culture-only theory's prediction that group differences in cognitive ability should track cultural practices and socioeconomic advantage.

    “Evidence contradicting the culture-only theory's prediction that group differences in cognitive ability should, in essence, track group differences in identifiable cultural practices and socioeconomic advantage (Section 12).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source
  • Findingcitation
    § Additional Evidence · p. 3

    As of 1999, all NAEP gaps for 9-, 13-, and 17-year-olds were still near or above the minimum expected by g theory.

    “As of 1999, all gaps for 9-, 13-, and 17-year-old students were still near or above the minimum expected (reading-0.80, 0.73, 0.73; math-0.82, 0.93, 1.06; and science-0.97, 1.06, 1.07).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gottfredson, in press

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Findingcitation
    § Consilience · p. 5

    Behavior genetic research suggests that relatively little, if any, of the Western Black-White difference in mature IQ could be due to shared family factors.

    “In fact, behavior genetic research suggests that relatively little, if any, of the Western Black-White difference in mature IQ could be due to the shared family factors that the culture-only theory has long presumed important (e.g., poverty, parents' education).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Scarr, 1997

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Findingcitation
    § Additional Evidence · p. 3

    Black-White achievement gaps in the 1971-1999 NAEP Trend Series were no larger or smaller than g theory would predict.

    “Second, Black-White achievement gaps in the 1971-1999 NAEP Trend Series were no larger or smaller than g theory would predict.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gottfredson, in press

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Findingcitation
    § Additional Evidence · p. 3

    Recent analyses show that critics who believe NAEP narrowing undermines the hereditarian hypothesis are mistaken.

    “Recent analyses (Gottfredson, in press) show the critics to be mistaken.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gottfredson, in press

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims. 21
  • Classified as probably not a substantial claim. 12

  • May combine two claims.

    Findingcitation
    § Contrasting Predictions · p. 3

    Cross-race identity of g factors and input-output achievement covariance matrices indicates commonality in cognitive architecture, contradicting predictions that different cultures create different intelligences.

    “This commonality in cognitive architecture is indicated, for instance, by cross-race identity of g factors and input-output achievement covariance matrices (Section 5). This commonality also contradicts predictions that different cultures create different intelligences.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Does the Hereditarian Hypothesis Leave Us Without Hope? · p. 8

    IQ 80 includes about 10% of Whites and a third of Blacks in the US and the segment most at risk for multiple health and social problems, regardless of family background and material resources.

    “It includes about 10% of Whites and a third of Blacks in the United States and the segment of both groups most at risk for multiple health and social problems, regardless of family background and material resources (Gottfredson, 1997, 2002).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Gottfredson, 1997 source
    • cites Gottfredson, 2002

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation
    § Replication · p. 4

    IQ correlates about .2 with skull size and about .4 with in vivo brain volume.

    “Small (.2) and moderate (.4) correlations of IQ, respectively, with skull size and in vivo brain volume (Section 6);”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Replication · p. 4

    Different IQ subtests' g loadings correlate .6-.7 with the magnitude of Black-White-East Asian mean differences and with measures of biological/genetic rootedness.

    “A moderately high correlation (usually .6-.7) of different IQ subtests' g loadings, not only with the magnitude of Black-White-East Asian mean differences on those subtests (Section 6) but also with measures of those subtests' rootedness in biological and genetic processes (e.g., heritability; Section 4);”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Additional Evidence · p. 3

    Nationally representative data on racial and ethnic IQ differences during the 20th century provide no evidence that the IQ gap has narrowed; standardized effect sizes averaged 1.02 across 20 samples.

    “First, nationally representative data on racial and ethnic IQ differences during the 20th century provide no evidence that the IQ gap has narrowed. Standardized effect sizes were 1.0 + 0.2 for both children and adults and for all ages and decades, averaging 1.02 across 20 samples.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gottfredson, in press

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation
    § Replication · p. 4

    Worldwide Black-White-East Asian differences exist in IQ, reaction time, and brain size, with Whites having intermediate scores.

    “Worldwide Black-White-East Asian differences in IQ (Section 3), reaction time (Section 4), and brain size, with Whites having the intermediate scores (Section 6);”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Consilience · p. 5

    The most g-loaded tests predict school and job performance best, and predict performance equally well for Blacks and Whites in the US and South Africa.

    “The most g -loaded tests predict school and job performance best, and they predict performance equally well for Blacks and Whites in both the United States and South Africa.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Additional Evidence · p. 3

    NAEP gaps narrowed from 1.07 SD in the 1970s to 0.89 in the 1990s, but the degree of narrowing stalled by the mid-1980s and differed by subject.

    “NAEP gaps narrowed from 1.07 standard deviation in the 1970s to 0.89 in the 1990s when averaged over all three subjects and ages. Degree of narrowing stalled by the mid-1980s and differed by subject: 25% in reading (1.06-0.79), 20% in math (1.07-0.87), and 15% in science (1.22-1.04).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gottfredson, in press

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation
    § Consilience · p. 4

    Black-White differences are essentially the same in the West (about 1 SD) across decade, age, and country, and are not substantially or permanently changed by interventions.

    “First the predicted uniformity: Black-White differences are essentially the same in the West (about 1 standard deviation) across decade, age, and country, and they are not substantially or permanently changed by interventions intended to do so (the point of Jensen's 1969 article).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jensen, 1969 source

  • May combine two claims.

    Findingcitation
    § Consilience · p. 5

    The g factor is highly heritable within races and has replicated metabolic, electrical, and structural correlates in the brain.

    “The g factor is highly heritable within races and also has replicated metabolic, electrical, and structural correlates in the brain, most of them also known to be heritable (these studies are mostly with Whites).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Consilience · p. 5

    The three-way race pattern for IQ/g differences has been replicated with reaction/inspection time and brain size, both highly heritable and correlated with g.

    “So far, the three-way race pattern for IQ/ g differences has been replicated with reaction/inspection time and brain size, both of which are highly heritable and correlated with g , as well as with a large collection of purely physical attributes (e.g., twinning).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Consilience · p. 5

    Major life outcomes (earnings, occupation, education) are moderately heritable, with half to two thirds of their heritability joint with g.

    “The g nexus goes full circle, from the social back to the genetic, because major life outcomes such as level of earnings, occupation, and education are also moderately heritable (respectively, about 40%-50%, 50%, and 60%-70%), with half to two thirds of their heritability being joint with g (see Gottfredson, 2002, for a review; studies limited so far to European Whites).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gottfredson, 2002

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingreasoning
    § Consilience · p. 6

    There is no evidence that racism-depressed motivation, racial stress, stereotype threat, or low self-esteem causes short- or long-term declines in actual cognitive ability.

    “However, there is no evidence that any of the factors causes either short- or long-term declines in actual cognitive ability.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation
    § Replication · p. 4

    Worldwide Black-White-East Asian mean differences exist in a large suite of biological and social variables, with the three races always in the same rank order.

    “Worldwide Black-White-East Asian mean differences in a large suite of biological variables (e.g., twinning, gestation time, sex ratio at birth) and social variables (e.g., law abidingness, marital stability), with the three races always in the same rank order (Section 10);”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Findingcitation
    § Replication · p. 4

    The heritability of IQ rises with age within races, and shared environmental effects on IQ virtually disappear by adolescence.

    “The rising heritability of IQ with age (within races) and the virtual disappearance by adolescence of any shared environmental effects on IQ (e.g., parental income, education, child-rearing practices; Section 5);”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • Probably not a substantial claim: may not pass S1 (asserted).

    Premisecitation
    § The Hereditarian Hypothesis: What Is It? · p. 1

    The hereditarian hypothesis is that Black-White differences in general intelligence (IQ, or g) are substantially genetic in origin, quantified as 50% genetic and 50% environmental.

    “Rushton and Jensen's (2005) hereditarian hypothesis is that Black-White differences in general intelligence (IQ, or the general mental ability factor, g ) are 'substantially' genetic in origin, which they quantify as 50% genetic and 50% environmental.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • May combine two claims.

    Premisecitation
    § Scientific Foundations of the Hereditarian Hypothesis: How Sound? · p. 1

    Within-group variability in phenotypic g has strong genetic roots and many physiological correlates in the brain.

    “that within -group variability in phenotypic g has strong genetic roots and many physiological correlates in the brain”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Deary, 2000 source

  • Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

    Interpretationreasoning
    § Rushton and Jensen's Policy Recommendations: Are They Warranted? · p. 7

    Lying about the enduring Black-White difference in phenotypic g would be both futile and harmful in the long run.

    “Lying about the enduring Black-White difference in phenotypic g would seem to be both futile and harmful in the long run.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Interpretationcitation
    § Rushton and Jensen's Policy Recommendations: Are They Warranted? · p. 7

    g theory can predict how large racial disparities in achievement will be in different settings, depending on demands for g and IQ distributions.

    “As Rushton and Jensen (2005) suggest, g theory can predict fairly accurately how large the racial disparities in achievement will be in different settings, depending on their demands for g and the IQ distributions of the groups involved.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given
    § Does the Hereditarian Hypothesis Leave Us Without Hope? · p. 8

    The risks that lower-IQ people face relative to more able individuals have been growing as the complexity of work, health care, and daily life has increased.

    “Moreover, the risks that lower-IQ people face in relation to more able individuals have been growing as the complexity of work, health care, and daily life has increased.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

    Interpretationreasoning
    § Rushton and Jensen's Policy Recommendations: Are They Warranted? · p. 6

    Proof that the Black-White IQ gap is partly genetic could be used to justify banning all racial preferences or, from a Rawlsian perspective, require substantial and permanent racial preferences.

    “For example, proof that the Black-White IQ gap is partly genetic could, depending on one's goals, be used to justify banning all racial preferences in employment and college admissions or, from a Rawlsian perspective (that genetic advantages are undeserved and unfair), require substantial and permanent racial preferences.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Replication · p. 3

    The major facts from Rushton and Jensen's Sections 3-6 and 10-12 have been replicated many times with independent data and are consistent with hereditarian theory but contradict culture-only theory.

    “The following major facts from Rushton and Jensen's (2005) Sections 3-6 and 10-12 have been replicated many times, and all with independent sources of data. All are consistent with hereditarian theory but contradict culture-only theory:”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given
    § Consilience · p. 4

    The g-based hereditarian theory is consilient: it connects g-related phenomena at genetic, physiological, psychometric, and socioeconomic levels into a coherent pattern yielding confirmed novel predictions.

    “The g -based hereditarian theory connects g -related phenomena at the genetic, physiological, psychometric, and socioeconomic levels to form a coherent pattern that yields novel predictions subsequently confirmed; it is consilient .”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationnone given
    § Consilience · p. 4

    Culture-only theory has become increasingly tattered, patched over by disconnected ad hoc speculation.

    “In contrast, culture-only theory has become increasingly tattered over time, patched over by disconnected ad hoc speculation.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationreasoning
    § Rushton and Jensen's Policy Recommendations: Are They Warranted? · p. 7

    Phenotypic differences in cognitive ability have relentless real-world effects that are neither ameliorated nor hidden by claims to the contrary.

    “Phenotypic differences in cognitive ability have relentless real-world effects that are neither ameliorated nor hidden by claims to the contrary.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based). May combine two claims.

    Interpretationnone given
    § Does the Hereditarian Hypothesis Leave Us Without Hope? · p. 8

    Less favorable genes for g impose constraints but do not prevent improving lives in crucial ways.

    “Less favorable genes for g impose constraints on individuals and their helpers, but they certainly do not prevent us from improving lives in crucial ways.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning
    § Rushton and Jensen's Policy Recommendations: Are They Warranted? · p. 8

    Lying about race differences in achievement is harmful because it foments mutual recrimination.

    “Lying about race differences in achievement is harmful because it foments mutual recrimination.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation
    § Rushton and Jensen's Policy Recommendations: Are They Warranted? · p. 6

    Rushton and Jensen (2005) make no recommendations for specific policies and correctly argue that the hereditarian hypothesis implies none in particular.

    “Rushton and Jensen (2005) make no recommendations for specific policies and correctly argue that the hereditarian hypothesis implies none in particular.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationcitation
    § Rushton and Jensen's Policy Recommendations: Are They Warranted? · p. 7

    By undermining culture-only explanations of racial inequality, the hereditarian hypothesis undermines the moral legitimacy of all rationales for racial equalization that posit White misbehavior as its cause.

    “By undermining culture-only explanations of racial inequality, the 'provisional truth' of Rushton and Jensen's (2005) hereditarian hypothesis thereby undermines the moral legitimacy of all rationales for racial equalization that posit White misbehavior as its cause.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton & Jensen, 2005 source
29 of 29

  • The paper relies on this without support.

    Regimes with environmentalist ideologies (Stalin and Pol Pot) exterminated as many of their citizens as did the Nazis, and virtually all victim groups of genocide in the 20th century had relatively high average levels of achievement.

    “One might note, in addition, that regimes with environmentalist ideologies (Stalin and Pol Pot) exterminated as many of their citizens as did the Nazis, and virtually all the victim groups of genocide in the 20th century had relatively high average levels of achievement (e.g., German Jews, educated Cambodians, Russian Kulaks, Armenians in Turkey, Ibos in Nigeria).”

  • The paper relies on this without support.

    The cognitive ability level below which federal law prohibits induction into the American military and below which no civilian jobs in the United States routinely recruit their workers is IQ 80.

    “This is the cognitive ability ('trainability') level below which federal law prohibits induction into the American military and below which no civilian jobs in the United States routinely recruit their workers.”

  • The paper relies on this without support.

    Culture-only theory entails 0% genetic and 100% environmental causation.

    “which entails 0% genetic and 100% environmental causation.”

  • The paper relies on this without support.

    The NAEP gaps are valid measures of achievement.

    “Black-White achievement gaps in the 1971-1999 NAEP Trend Series were no larger or smaller than g theory would predict.”
4 of 4

Cites

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Research works printed but not linked: 1

  1. Gottfredson, (in press). Implications of cognitive differences for schooling within diverse societies.

Cited by

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Related

Authors
Gottfredson, L. S.
Affiliations
University of Delaware (US)
Corresponding author
Gottfredson, Linda S.
ORCID
Gottfredson, Linda S.
Venue
Psychology, Public Policy, and Law
Publisher
American Psychological Association (APA)
Published
2005-06
Volume
11
Issue
2
Pages
311-319
ISSN
  • 1076-8971 (ISSN-L)
  • 1939-1528
DOI
10.1037/1076-8971.11.2.311
OpenAlex
W2148599684
Semantic Scholar
17df3453bdb1cc7901ba633b23c45ce0df2ef346
Cited by
60
References
58
Citations by year
2024: 2 · 2023: 5 · 2022: 1 · 2021: 3 · 2019: 2 · 2018: 7 · 2017: 2 · 2016: 1 · 2015: 2 · 2014: 3 · 2013: 1 · 2012: 4
FWCI
7.37
Type
journal article
Language
en
Open access
closed
Locations
Psychology Public Policy and Law (publishedVersion)
Topics
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Cognitive Abilities and Testing
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Race, Genetics, and Society
  • Social Sciences › Sociology and Political Science › Intergenerational and Educational Inequality Studies
Keywords
public policy implications, race and intelligence

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