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Eysenck, Hans Jurgen

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Hans Jurgen Eysenck was an influential British psychologist who became the scion of twentieth-century psychometry. Eysenck believed that intelligence was highly inheritable and that racial differences in IQ were mainly due to genetic differences among races. He formulated racial arguments that would stimulate the careers of his two most famous students, Arthur Jensen and J. Philippe Rushton. Eysenck wasborninBerlin, Germany, onMarch 4,1916.Ironically, he left the country in 1934 in protest of the Nazi movement. His professional education occurred at London University, where he earned a Ph.D. in psychology under Cyril Burt in 1940. During World War II he was chief psychologist at the Mill Hill Emergency Hospital. After the war he founded the Psychology Department at the University of London’s Institute of Psychiatry, where he worked as a professor until 1983.

Eysenck’s academic and professional achievements were legion. He founded the first clinical psychology program in England, published more than 1,000 professional journal articles by the time of his death, introduced statistical analysis to a wide range of psychological data, popularized psychology by writing books for the general public, and advocated for the genetic basis of intelligence and the role of genetics in determining racial differences in IQ.

Eysenck suggested that there was an essential distinction between three classes of phenomena associated with cognitive performance. He defined Intelligence A as the biological substrate of mental ability resulting from the brain’s neuroanatomy and physiology. Intelligence B is the manifestation of intelligence A and of those things that influence its expression in real life behavior. Intelligence C is the level of performance on psychometric tests of cognitive ability. Eysenck recognized that both genetic and environmental influences contributed to all three attributes of intelligence, but he asserted that the heritability (genetic component) of these was high (80%). In this way, he never broke with the views of his mentor Cyril Burt, who had previously asserted the overwhelming influence of genes on IQ. His lifelong views on this subject are set out in The Intelligence Controversy , a debate with Leo Kamin published in 1981, and in Intelligence: A New Look , published in 1998, after his death. He was also a signatory of “The Mainstream Science on Intelligence,” a manifesto published in the Wall Street Journal on December 13, 1994. The document was drafted in response to criticism of Richard Herrnstein and Charles Murray’s The Bell Curve , which had been published earlier that year. The Bell Curve stated that general intelligence was the main factor determining one’s position in society. Thus the concentration of African Americans in the lowest social positions in society was not due to historical and ongoing discrimination, it was due to their lower mean IQ. Criticisms of the book entailed its non-professional use of statistical inference and its classification of humans into discrete racial groups, matching the social conceptions of race used in America. The mainstream statement was meant to weaken these criticisms by lending the authority of the psychometricians to the core claims of The Bell Curve .

Eysenck’s views on race, genetics, and IQ were published in The IQ Argument: Race, Intelligence, and Education (1971). He based his supposition that genetics is responsible for racial differences in IQ on the long-standing 15-point IQ differential between whites and blacks in America. He further noted that there was greater variability in white IQ scores than in black IQ scores. This suggested that there would be a greater percentage of whites in both the lowest and the highest IQ categories. Blacks were said to perform better on aspects of the IQ test that resulted from education as opposed to innate ability. These results, Eysenck claimed, were supported by studies of blacks around the world, including in Uganda, Jamaica, Tanzania, South Africa, and Ghana (average IQ scores between 70 and 80.) Furthermore he argued that the fact that Japanese and Chinese performed better than whites did on IQ tests that measured innate ability, as opposed to learned abilities, was evidence of the genetic superiority of these groups with regard to intelligence. Finally, he suggested that Jews were the most genetically gifted population, with a 300 percent greater proportion of Nobel Prize winners than non-Jews.

Eysenck’s career and contributions may be best understood in the context of a researcher that overstated one aspect of his problem (genetics) in response to what seemed to him an irrational denial of its role in human cognition. Modern genetic analyses have conclusively demonstrated that intelligence, broadly defined, is inherited to some extent. However, most estimates of the heritability of intelligence, however defined, range between 30 and 50 percent, as opposed to Eysenck’s 80 percent. Yet it is important to understand that conceding the heritability of intelligence does not mean that it plays the roles ascribed to it by the psychometrician research program as outlined by Galton, Burt, Eysenck, Herrnstein, and Rushton. In other words, there is little evidence that intelligence determines social structure, as opposed to one’s social position determining one’s manifested intelligence. Furthermore, the case for genetic determination of racial IQ differentials is always weakened by the absence of shared environmental conditions between the racially oppressed and the racially dominant. Genomic research that examines quantitative trait loci is underway. This work will eventually identify loci that contribute to an individual’s cognitive function and will most likely identify hundreds of loci whose influences are profoundly influenced by multiple and complex environmental influences. Such a result will demonstrate that the main point of the psychometricists is correct, that genes do influence cognitive function, but it will also demonstrate that these effects are far more complicated than they suggest.

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