Race and Intelligence: ‘The Bell Curve’ 20 Years Later

20 years after its initial publication, The Bell Curve co-author Charles Murray is revisiting his book’s troubling arguments about race and IQ. But The Bell Curve is part of a much longer history of arguments about race and intelligence, critically rooted in early scientific racism and later, the eugenics movement. We revisit this history and its implications for Murray’s familiar brand of modern scientific racism.

Racial hierarchies have long relied on assumptions that (1) races are biologically distinct and differentiable categories, and (2) that these races differ in important physical, behavioral, and intellectual capacities. Early iterations of scientific racism, such as the influential 1854 book Types of Mankind  (authored by Josiah Clark Nott and George Robins Gliddon), argued for an evolutionary ladder of humankind that positioned Europeans at the top and blacks (caricatured as physically and behaviorally similar to the Great Apes) at the bottom.

Types of Mankind, 1854

50 years later, eugenicists offered a uniquely modern take on the question of race and intelligence through the use of “standardized” intelligence test, such as the Stanford-Binet test, the predecessor to the modern IQ test. The results of these seemingly “objective” tests allowed eugenicists to deploy hard data in support of their theories of racial superiority/inferiority. Similar tests were also used to “diagnose” intellectual disability, with test results leading to the exclusion of “mentally inferior” immigrants, and mass institutionalization and sterilization of “feebleminded” individuals.

1146-Europe-as-an-emigrant-exporting-continent-Harry-H-Laughlin-testimony-before-the-House-Committee-including-Immigration-Restriction-Act copy
Number of US Army officers showing “superior or very superior” intelligence by race and country of origin. From testimony given by ERO superintendent Harry Laughlin to the House of Representatives during hearings on immigration restriction, March 1924.
5 Imbecile Scale
Widely circulated “imbecile scale” from the 1920s and 30s. Each “step” was defined by a “mental age” determined by performance on the Stanford-Binet test.
Sample Binet test, c. 1921. From the Image Archive on the American Eugenics Movement.
01 Differ in Mental Capacity (dragged)
Lecture draft: “Do races differ in mental capacity?” By ERO Director Charles B. Davenport, n.d.

Today similar arguments about race and intelligence continue to be redeployed. Famously, 1994’s The Bell Curve and Nicholas Wade’s recent book A Troublesome Inheritance: Genes, Race, and Human History argued that the supposed “fact” of racial differences in intelligence (as measured by IQ tests) necessitated societal reckoning, regardless of political correctness.


In a Q+A marking the 20 year anniversary of The Bell Curve, co-author Charles Murray stood stoically by the book’s pronouncements:

“There is a mean difference in black and white scores on mental tests, historically about one standard deviation in magnitude on IQ tests (IQ tests are normed so that the mean is 100 points and the standard deviation is 15). This difference is not the result of test bias, but reflects differences in cognitive functioning.”

Murray goes on to argue that academia has silenced conversations about racial differences in intelligence due to “political correctness,” which he likens to “corruption.”

But critics like author Stephen Murdoch (IQ: The Brilliant Idea That Failed) have long questioned the very existence of a measurable “general intelligence” that IQ tests purport to measure:

“The theory of general intelligence is the very foundation of mainstream intelligence testing over the past century, but even the most ardent proponents of g (general intelligence) will admit that it has not been unquestionably established… Until there is proof beyond statistical relationships of g‘s existence and measurability, society should not treat IQ tests as if they can meaningfully rank people along a continuum of innate intelligence. For the same reason, all inferences based on IQ test results about race differences are dangerously unfounded.” – IQ, pp. 229

How do we define intelligence – let alone measure it? From a historical perspective,  it seems proponents of standardized testing have been less interested in the objective answers than in testing’s usefulness in reconstructing tired hierarchies of humankind.