page_title: History of the race and intelligence controversy
section_title: 1920–1960
hierarchical_section_title: History of the race and intelligence controversy / History / 1920–1960
context_page_description: The history of the race and intelligence controversy concerns the historical development of a debate about possible explanations of group differences encountered in the study of race and intelligence. Since the beginning of IQ testing around the time of World War I, there have been observed differences between average scores of different population groups, but there has been no agreement about whether this is mainly due to environmental and cultural factors, or mainly due to some as yet undiscovered genetic factor, or even if the dichotomy between environmental and genetic factors is the most effective approach to the debate.
  In the late 19th and early 20th century, group differences in intelligence were assumed to be racial in nature; apart from intelligence tests, research relied on measurements such as brain size or reaction times. By the mid-1940s most psychologists had adopted the view that environmental and cultural factors predominated. In the mid-1960s, physicist William Shockley sparked controversy by claiming there might be genetic reasons that black people in the United States tended to score lower on IQ tests than white people.
context_section_description: In the 1920s, psychologists started questioning underlying assumptions of racial differences in intelligence; although not discounting them, the possibility was considered that they were on a smaller scale than previously supposed and also due to factors other than  heredity. In 1924, Floyd Allport wrote in his book Social Psychology that the French sociologist Gustave Le Bon was incorrect in asserting "a gap between inferior and superior species", and pointed to "social inheritance" and "environmental factors" as accounting for differences. Nevertheless, he suggested that: "the intelligence of the white race is of a more versatile and complex order than that of the black race. It is probably superior to that of the red or yellow races."
  In 1929, Robert Woodworth, in his textbook Psychology: A Study of Mental Life, made no claims about innate differences in intelligence between races, pointing instead to environmental and cultural factors. He considered it advisable to "suspend judgment and keep our eyes open from year to year for fresh and more conclusive evidence that will probably be discovered".
  
  In the 1930s, the English psychologist Raymond Cattell wrote three tracts, Psychology and Social Progress (1933), The Fight for Our National Intelligence (1937) and Psychology and the Religious Quest (1938). The second was published by the Eugenics Society, of which he had been a research fellow; it predicted the disastrous consequences of not stopping the decline in the average intelligence in Britain by one point per decade. In 1933, Cattell wrote that, of all the European races, the "Nordic race was the most evolved in intelligence and stability of temperament". He argued for "no mixture of bloods between racial groups" because "the resulting re-shuffling of impulses and psychic units throws together in each individual a number of forces which may be incompatible". He rationalised the "hatred and abhorrence ... for the Jewish practice of living in other nations instead of forming an independent self-sustained group of their own", referring to them as "intruders" with a "crafty spirit of calculation".  He recommended a rigid division of races, referring to those suggesting that individuals be judged on their merits, irrespective of racial background, as "race-slumpers". He wrote that in the past, "the backward branches of the tree of mankind" had been lopped off as "the American Indians, the Black Australians, the Mauris and the negroes had been driven by bloodshed from their lands", unaware of "the biological rationality of that destiny". He advocated what he saw as a more enlightened solution: by birth control, by sterilization, and by "life in adapted reserves and asylums", where the "races which have served their turn [should] be brought to euthanasia." 
   He considered blacks to be naturally inferior, on account of "their small skull capacity". In 1937, he praised the Third Reich for their eugenic laws and for "being the first to adopt sterilization together with a policy of racial improvement".  In 1938, after newspapers had reported on the segregation of Jews into ghettos and concentration camps, he commented that the rise of Germany "should be welcomed by the religious man as reassuring evidence that in spite of modern wealth and ease, we shall not be allowed ... to adopt foolish social practices in fatal detachment from the stream of evolution". In late 1937, Cattell moved to the US on the invitation of the psychologist Edward Thorndike of Columbia University, also involved in eugenics. He spent the rest of his life there as a research psychologist, devoting himself after retirement to devising and publicising a refined version of his ideology from the 1930s that he called beyondism.
  In 1935, Otto Klineberg wrote two books, Negro Intelligence and Selective Migration and Race Differences, dismissing claims that African Americans in the northern states were more intelligent than those in the south. He argued that there was no scientific proof of racial differences in intelligence and that this should not therefore be
caption: Franz Boas, regarded as the father of anthropology in the US,[40] had a lasting influence on the work of Otto Klineberg and his generation
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