Dans la mesure où le chômage est nécessaire (Cahuc & Zylberberg 2005) pour permettre aux industries désuètes de péricliter au profit des industries nouvelles qui tendent à se conformer aux changements des préférences individuelles, un chômage frictionnel émerge.
Bien entendu, le chômage causé par les réglementations du marché du travail (salaire minimum, syndicats) est considéré comme étant involontaire. Les économistes ne le nient pas. Mais certains économistes souscrivent quand même à l’idée que le chômage frictionnel pourrait être également de nature “involontaire”.
Under the Skin: On the Impartial Treatment of Genetic and Environmental Hypotheses of Racial Differences
David C. Rowe 2005
University of Arizona
Environmental and genetic explanations have been given for Black–White racial differences in intelligence and other traits. In science, viable, alternative hypotheses are ideally given equal Bayesian prior weights; but this has not been true in the study of racial differences. This article advocates testing environmental and genetic hypotheses of racial differences as competing hypotheses. Two methods are described: (a) fitting means within structural equation models and (b) predicting means of interracial children. These methods have limitations that call for improved research designs of racial differences. One improvement capitalizes on biotechnology. Genetic admixture estimates — the percentage of genes of European origin that a Black individual possesses (independent of genes related to skin coloration) — can represent genetic influences. The study of interracial children can be improved by increasing sample size and by choosing family members who are most informative for a research question. Eventually, individual-admixture estimates will be replaced by molecular genetic tests of alleles of those genes that influence traits.
Charles Murray (2006, 2008) disputes Dickens and Flynn’s study (2006) “Black Americans reduce the racial IQ gap: Evidence from standardization samples” showing a decrease in Black-White IQ differences. In fact, the Black-White gap shows no decrease. He further suggests (2008) in another study that the IQ of black americans could be 78, not 85, during the World War I, given a gap of 1.52σ instead of 1.16σ. Based on Murray’s conclusion, Rushton and Jensen (2010) hypothesized that the actual B-W gap could be 1.52σ (with an average black american IQ near 78) to the extent that studies excluded the poorest african americans, who lived in the rural South.
Race: a social destruction of a biological concept
It is nowadays a dominant opinion in a number of disciplines (anthropology, genetics, psychology, philosophy of science) that the taxonomy of human races does not make much biological sense. My aim is to challenge the arguments that are usually thought to invalidate the biological concept of race. I will try to show that the way ‘‘race’’ was defined by biologists several decades ago (by Dobzhansky and others) is in no way discredited by conceptual criticisms that are now fashionable and widely regarded as cogent. These criticisms often arbitrarily burden the biological category of race with some implausible connotations, which then opens the path for a quick eliminative move. However, when properly understood, the biological notion of race proves remarkably resistant to these deconstructive attempts. Moreover, by analyzing statements of some leading contemporary scholars who support social constructivism about race, I hope to demonstrate that their eliminativist views are actually in conflict with what the best contemporary science tells us about human genetic variation.
Those who subscribe to the opinion that there are no human races are obviously ignorant of modern biology.
Ernst Mayr, 2002
Black-White differences on IQ and grades: The mediating role of elementary cognitive tasks
Bryan J. Pesta, Peter J. Poznanski (2008)
The relationship between IQ scores and elementary cognitive task (ECT) performance is well established, with variance on each largely reflecting the general factor of intelligence, or g. Also ubiquitous are Black–White mean differences on IQ and measures of academic success, like grade point average (GPA). Given C. Spearman’s (Spearman, C. (1927). The Abilities of Man. New York: Macmillan) hypothesis that group differences vary directly with a test’s g loading, we explored whether ECT performance could mediate Black–White IQ and GPA differences. Undergraduates (139 White and 40 Black) completed the Wonderlic Personnel Test, followed by inspection time and choice reaction time ECTs. Despite restriction of range, ECT performance completely mediated Black–White differences on IQ (d=.45). Group differences on GPA (d=.73), however, were larger and ECT performance did not mediate them. We discuss findings in light of Spearman’s hypothesis.
Racial differences in narcissistic tendencies
Virgil Zeigler-Hill, Marion T. Wallace
Black individuals have been found to report the highest levels of self-esteem of any racial group in the United States. The purpose of the present research was to examine whether Black individuals also report higher levels of narcissism than White individuals. Study 1 (N = 367) found that Black individuals reported higher levels of narcissism than White individuals even when controlling for gender, self-esteem level, and socially desirable response tendencies. Study 2 (N = 967) and Study 3 (N = 315) found similar results such that Black individuals reported higher levels of narcissism than White individuals on the narcissism measures that captured less pathological facets of this construct. Study 3 also included indicators of psychological adjustment and found that the pathological aspects of narcissism were more strongly associated with maladjustment for Black individuals than for White individuals. The implications of these results for understanding the Black self-esteem advantage are discussed.
Genetic contributions to stability and change in intelligence from childhood to old age
Ian J. Deary, Jian Yang, Gail Davies, Sarah E. Harris, Albert Tenesa, David Liewald, Michelle Luciano, Lorna M. Lopez, Alan J. Gow, Janie Corley, Paul Redmond, Helen C. Fox, Suzanne J. Rowe, Paul Haggarty, Geraldine McNeill, Michael E. Goddard, David J. Porteous, Lawrence J. Whalley, John M. Starr & Peter M. Visscher. 2012.
Understanding the determinants of healthy mental ageing is a priority for society today. So far, we know that intelligence differences show high stability from childhood to old age and there are estimates of the genetic contribution to intelligence at different ages. However, attempts to discover whether genetic causes contribute to differences in cognitive ageing have been relatively uninformative. Here we provide an estimate of the genetic and environmental contributions to stability and change in intelligence across most of the human lifetime. We used genome-wide single nucleotide polymorphism (SNP) data from 1,940 unrelated individuals whose intelligence was measured in childhood (age 11 years) and again in old age (age 65, 70 or 79 years). We use a statistical method that allows genetic (co)variance to be estimated from SNP data on unrelated individuals. We estimate that causal genetic variants in linkage disequilibrium with common SNPs account for 0.24 of the variation in cognitive ability change from childhood to old age. Using bivariate analysis, we estimate a genetic correlation between intelligence at age 11 years and in old age of 0.62. These estimates, derived from rarely available data on lifetime cognitive measures, warrant the search for genetic causes of cognitive stability and change.