The aim of this paper is to evaluate the kind of evidence and arguments used to support Richard Lynn's increasingly influential doctrine that genetically determined differences in population IQ are the main cause of differences in regional and national levels of socio‐economic development and public health status.
The paper's approach is two‐fold. First, new data on the correlation between regional differences in educational achievement of Italian schoolchildren and regional differences in socio‐economic development are presented in order to test the validity of Lynn's report that there is a progressive North‐to‐South reduction of Italian regional IQ that is highly correlated with a corresponding North‐to‐South reduction in the level of socio‐economic development. Second, a thorough and systematic review of the content of Lynn's article is carried out in order to assess the validity of the data, methods, and arguments normally used to support his socio‐economic doctrine.
Lynn's study uses regional differences in the performance of Italian secondary school children on Organisation for Economic Co‐operation and Development tests of educational achievement to assess regional IQ differences. However, data on Italian regional differences in educational achievement obtained in a much larger INVALSI study of 2,089,829 Italian schoolchildren provide unequivocal evidence that Lynn's educational achievement measure is not a valid index of IQ differences. More generally, the lengthy literature review in Lynn's article reveals uncritical acceptance of reported correlations between any putative index of IQ and socio‐economic variables. Any measure of cognitive performance that is correlated with IQ is considered a measure of IQ, even if there is only a weak correlation. All correlations between such measures and socio‐economic or public health variables are viewed as evidence of direct causal relationships. In all cases, causality is assumed to be in the direction that supports Lynn's doctrine when it would be equally valid to argue that socio‐economic and public health differences cause differences in the performance of IQ tests. In addition to these fundamental logical and statistical errors the present report records numerous other data processing, methodological, and conceptual errors.
The value of the present article is that it demonstrates the flawed manner in which data are interpreted and analysed in order to support Lynn's thesis. Left unchallenged, this pernicious doctrine would promote a socially damaging conception of critically important socio‐economic and public health issues that would discourage the adoption of national policies designed to increase levels of socio‐economic development and improve public health status.
Robinson, D., Saggino, A. and Tommasi, M. (2011), "The case against Lynn's doctrine that population IQ determines levels of socio‐economic development and public health status", Journal of Public Mental Health, Vol. 10 No. 3, pp. 178-189. https://doi.org/10.1108/17465721111175056
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