Arthur R. Jensen > Quotes

“Should the discovery of fire have been avoided because arsonists can misuse it? Any kind of information can be misused by those who are determined to do so. The place to stop the misuse of knowledge is not at the point of inquiry, but at the point of misuse.”
― Arthur R. Jensen, Straight Talk About Mental Tests

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It is a common misconception that psychological measurements of human abilities are generally more prone to error or inaccuracy than are physical measurements. In most psychological research, and especially in psychometrics, this kind of measurement error is practically negligible. If need be, and with proper care, the error variance can usually be made vanishingly small. In my laboratory, for example, we have been able to measure such variables as memory span, flicker-fusion frequency (a sensory threshold), and reaction time (RT) with reliability coefficients greater than .99 (that is, less than 1 percent of the variance in RT is due to errors of measurement). The reliability coefficients for multi-item tests of more complex mental processes, such as measured by typical IQ tests, are generally about .90 to .95. This is higher than the reliability of people's height and weight measured in a doctor's office! The reliability coefficients of blood pressure measurements, blood cholesterol level, and diagnosis based on chest X-rays are typically around .”
― Arthur R. Jensen, The g Factor: The Science of Mental Ability

“As the number of studies increases (...) the investigator is then prompted to examine the anomalous study to find out in what crucial conditions it differs from other studies yielding contrary results. Scientific investigation is the analysis of variables, not just a box score tallying how may studies are pro or con some conclusion.”
― Arthur R. Jensen, Bias in Mental Testing

“There is a perhaps understandable reluctance to come to grips scientifically with the problem of race differences in intelligence—to come to grips with it, that is to say, in the same way the scientists would approach the investigation of any other phenomenon. This reluctance is manifested in a variety of ‘symptoms’ found in most writings and discussions of the psychology of race differences. These symptoms include a tendency to remain on the remotest fringes of the subject, to sidestep central questions, and to blur the issues and tolerate a degree of vagueness in definitions, concepts and inferences that would be unseemly in any other realm of scientific discourse. Many writers express an unwarranted degree of skepticism about reasonably well-established quantitative methods and measurements. They deny or belittle facts already generally accepted—accepted, that is, when brought to bear on inferences outside the realm of race differences—and they demand practically impossible criteria of certainty before even seriously proposing or investigating genetic hypotheses, as contrasted with with extremely uncritical attitudes towards purely environmental hypotheses. There is often a failure to distinguish clearly between scientifically answerable aspects of the question and the moral, political and social policy issues; there is tendency to beat dead horses and set up straw men on what is represented, or misrepresented I should say, as the genetic side of the argument. We see appeals to the notion that the topic is either too unimportant to be worthy of scientific curiosity, or is too complex, or too difficult, or that it will be forever impossible for any kind of research to be feasible, or that answers to key questions are fundamentally ‘unknowable’ in any scientifically accepted sense. Finally, we often see complete denial of intelligence and race as realities, or as quantifiable attributes, or as variables capable of being related to one another. In short, there is an altogether ostrich-like dismissal of the subject.”
― Arthur R. Jensen, Genetics and education

“Test scores themselves are merely correlates, predictors and indicators of other socially important variables, which would not be altered in the least if tests did not exist. The problem of individual differences and group differences would not be made to disappear by abolishing tests. One cannot treat a fever by throwing away the thermometer.”
― Arthur R. Jensen, Bias in Mental Testing

“The IQ, interestingly enough, shows a higher degree of assortative mating in our society than any other measurable human characteristic. I have surveyed the literature on this point, based on studies in Europe and North America, and find that the correlation between spouses’ intelligence test scores average close to +0.60.”
― Arthur R. Jensen, Genetics and education