The Trend of National Intelligence

Abstract

IN the Galton Lecture for 1946, Prof. Godfrey Thomson marshalls the evidence that leads him to the conclusion that there is at the present time in Britain, and has been for at least twenty-five years, a correlation of approximately –0·25 between the intelligence score of a child of about eleven years and the size of the family of which he (or she) is a member. The facts are no longer in dispute : yet it makes a profound difference to the points of policy on which emphasis might be laid, if any attempt were made to reverse the present tendency, whether the interpretation of the facts is that the average level of innate intelligence in the country is declining, or that the facts merely indicate a differential environmental influence on intelligence test scores. To obtain an accurate interpretation would involve, as Carr-Saunders and Burt point out in their contributions to the symposium in 1947 which followed Thomson‘s Galton Lecture, a team of research geneticists, psychologists, statisticians and sociologists backed by a heavy endowment. Thomson‘s interpretation, on the basis of his own and other people‘s carefully prepared investigations, is that hereditary factors are causing a decline in the national intelligence of at least one point in I.Q. per generation, and probably more.

The Trend of National Intelligence

By Prof. Godfrey Thomson, with a Symposium by Sir Alexander Carr-Saunders, Sir Cyril Burt, Prof. Lionel Penrose and Prof. Godfrey Thomson. Pp. 35. (London: The Eugenics Society and Hamish Hamilton.) 2s. net.