The Art wrote many wise things in his numerous publications. Below are some of the quotes we like. Quotes are always presented with the entire paragraph to avoid misunderstandings and quote mining by (political) opponents.

Way back in 1972, at the Davis campus of the University of California, I was having lunch with the evolutionary geneticist Theodosius Dobzhansky. He had invited me to come to Davis and discuss the manuscript of my book Educability and Group Differences (Jensen, 1973), on which I had solicited his comments. (He was a respectful and friendly critic.) On that same day, the campus newspaper gave notice of a speech to be delivered by one of the leading figures in the Creationist crusade that aimed to banish Darwin from the biology textbooks used in California high schools. The article also stated that this Biblical Fundamentalist had challenged Dobzhansky (who was then the world’s foremost expert on the genetic theory of evolution) to a debate on Creationism, and that Dobzhansky had declined the offer. I asked him why. He said he had long since reached the conclusion that any argument between persons who were not in at least ninety percent agreement on the issues was a total waste from a scientific standpoint, although he conceded that a poorly informed audience might find it entertaining. I have remembered Dobzhansky’s wise advice ever since, but have rarely had occasion to act on it. In reading Brace’s review, however, I deemed it is most appropriate to do so.

Arthur R. Jensen (2000) Name-calling is a Disappointing Substitute for Real Criticism. Psycoloquy: 11(009) Intelligence g Factor (25)

15. It is amazing to see a reference to Wissler’s (1901) primitive study, which has been used in generations of psychology textbooks to discredit the Galtonian analytical-physical approach to the study of individual differences in mental ability. The great amount of fruitful research in recent years showing highly significant and theoretically important relationships between chronometric measures of information processing speed in various experimental tasks (Jensen, 1998, Chapter 8; Vernon, 1987) has completely contradicted the conclusions nearly every psychologist in the past (except Spearman, 1904) drew from Wissler’s conspicuously flawed study.

16. Indeed, the uncritical acceptance of Wissler’s findings inhibited research on mental chronometry for more than half a century. The gist of this story is that Wissler reported an utterly nonsignificant correlation of -.02 between measures of reaction time (RT) and “intelligence.” There were no IQ tests at that time, so class grades in mathematics and classics were used as the measure of intelligence. The subjects were undergraduates in Columbia University, a group highly selected for scholastic aptitude (which is highly g-loaded). The reliability of the RT test is estimated at between .15 and .20. In those days virtually nothing was known about psychometrics, so the attenuation of the correlation coefficient by low reliability and severe restriction of the range-of-talent was not considered.

17. The failure to reject the null hypothesis in this famous study is an extreme and classic case of the statistician’s Type II error, i.e., not rejecting the null hypothesis when it is false. The same was true of the other Galtonian tests used by Wissler, such as measures of visual, auditory, and haptic discrimination. In recent years, all these variables have been found to be correlated with g. These Galtonian kinds of measurements, implemented by modern technology, may afford more direct and pointed means of discovering the physiological basis of g than the much more complex mental tasks used to measure IQ. Psychology is now moving, I believe, in both a more analytical and a more biological direction and shows healthy signs of recovering from the scientifically unfortunate influences from its past history — dualism, subjectivism, hollow-organism behaviorism, and environmentalism sans genetics.

Arthur R. Jensen (2000) Psychometric Scepticism. Psycoloquy: 11(039) Intelligence g Factor (38)

28. Finally, a word on behalf of the consilience of scientific knowledge. I have read E. O. Wilson’s book “Consilience” (Wilson, 1998) and liked it a lot, mainly because long before I even knew this word, I had been a consilience seeker in my personal philosophy, as a way of seeking the interrelatedness of many different things within a scientific context. This appeals to me as an absolute non-believer in anything supernatural and as one who has sought a scientifically satisfying general philosophy or world view. Therefore I am happy to find that Anderson characterizes my notion of the “g nexus” (Jensen, 1998, Chapter 14) as an example of consilience, even though it is quite limited in view of Wilson’s all-embracing conception. Admittedly, the “g nexus” is at present just an idea for a broad research program, which I expect to come about as a connecting (not to say unifying) theme in the behavioral and social sciences. With or without a structural theory of intelligence per se, the g construct is there and its role in extra-psychometric variables of educational, social, economic, and personal importance can be determined and studied, even while our understanding of the physical basis of g is far from complete. Progress in understanding that most central aspect of the g nexus will accelerate along with the technical advances and discoveries being made today in brain research. More than one path will lead to the scientific understanding of g, which is clearly one of the most important constructs in human psychology.

Arthur R. Jensen (2000) “the g Factor” is About Variance in Human Abilities,. Psycoloquy: 11(041) Intelligence g Factor (40)

12. Even in livestock, after intensive artificial selection over many generations for a given trait (e.g., egg-laying capacity in chickens, milk yield in cows, back fat in pigs, or beef yield in cattle), the traits maintain moderate heritability, which, under relaxed selection, rapidly increases. Selection reduces mainly the additive component of genetic variance, thereby causing the interactive or nonadditive components (dominance and epistasis) to constitute a larger proportion of the total genetic variance. Less advantageous alleles at a given locus are gradually eliminated by natural selection when heterozygosity lends no advantage to fitness. Heterozygosity with moderate to high heritability is maintained in polygenic traits with balanced selection, such as height and IQ. At this point in history, however, arguments that genetic factors do not play a major role in human variation in mental abilities, particularly in the component of test score variance identified as g, can truly be likened to the creationists’ rejection of evolution by natural selection.

Arthur R. Jensen (2000) Nothing ‘mystifying’ About Psychometric g. Psycoloquy: 11(042) Intelligence g Factor (41)

Differential Psychology: Towards Consensus (1987)

This reflective ending chapter in the book contains particularly many interesting comments.

Modgil, Sohan, and Celia Modgil, eds. Arthur Jensen: Consensus and Controversy. Vol. 4. Routledge, 1987. “DIFFERENTIAL PSYCHOLOGY: TOWARDS CONSENSUS”

  • I had begun by trying, for the sake of scholarly thoroughness, merely to write a short chapter for my book on the ‘culturally disadvantaged’ that I expected would succinctly review the so-called nature-nurture issue only to easily dismiss it as being of little or no importance for the subsequent study of the causes of scholastic failure and success. I delved into practically all the available literature on the genetics of intelligence, beginning with the works of the most prominent investigator in this field, Sir Cyril Burt, whom I had previously heard give a brilliant lecture entitled The Inheritance of Mental Ability’ at University College, London in 1957. The more I read in this field, the less convinced I became of the prevailing belief in the all-importance of environment and learning as the mechanisms of individual and group differences in general ability and scholastic aptitude. I felt even somewhat resentful of my prior education, that I could have gone as far as I had—already a fairly well-recognized professor of educational psychology—and yet could have remained so unaware of the crucial importance of genetic factors for the study of individual differences.
    • p. 424
  • It was little consolation that I had been ‘in good company’ in my ignorance of genetics; in fact, that aspect of the situation seemed even more alarming to me. I was overwhelmed by the realization of the almost Herculean job that would be needed to get the majority of psychologists and educators fully to recognize the importance of genetics for the understanding of variation in psychological traits. Hence, rather than attempting at first to add small increments of original empirical research to the body of knowledge on the genetics of human abilities, I thought my most useful role at that point was a primarily didactic one.
    • p. 424
  • The study of inbreeding depression seems to me especially important in the study of human abilities, because inbreeding depression indicates genetic dominance, and the presence and degree of dominance are related to natural selection for the trait in the course of its biological evolution. It was of great interest to me to discover, for example, that of the several ability factors that can be extracted from the various subtests of the Wechsler Intelligence Scale for Children, the one that shows the greatest susceptibility to inbreeding depression is the g factor (Jensen, 1983b). This finding indicates that one of our most widely used standard psychometric tests of intelligence yields scores that reflect some part of the variance in the biological intelligence that has developed in the course of human evolution.
    • p. 424
  • The key theme in Gordon’s chapter, that lends it theoretical coherence, is his clear perception that the guiding force in my own work in mental measurement arises principally from my constant search for construct validity that can embrace the widest range of phenomena in differential psychology. In my philosophy, science is an unrelenting battle against ad hoc explanation. No other field in psychology with which I have been acquainted has been so infested by ad hoc theories as the attempts to explain social class, racial, and ethnic group differences on various tests of mental ability. My pursuit of what I have called the Spearman hypothesis (Jensen, 1985a), which is nicely explicated by Gordon, represents an effort to displace various ad hoc views of the black-white differences on psychometric tests by pointing out the relationship of the differences to the g loadings of tests, thereby bringing the black-white difference into the whole nomothetic network of the g construct. It is within this framework, I believe, that the black-white difference in psychometric tests and all their correlates, will ultimately have to be understood. Understanding the black-white difference is part and parcel of understanding the nature of g itself. My thoughts about researching the nature of g have been expounded in a recent book chapter (Jensen, 1986b). Enough said. Gordon’s chapter speaks for itself, and, with his three commentaries on the chapters by Osterlind, Shepard, and Scheuneman, leaves little else for me to add to this topic.
    • pp. 430-1
  • The study of race differences in intelligence is an acid test case for psychology. Can behavioral scientists research this subject with the same freedom, objectivity, thoroughness, and scientific integrity with which they go about investigating other psychological phenomena? In short, can psychology be scientific when it confronts an issue that is steeped in social ideologies? In my attempts at self- analysis this question seems to me to be one of the most basic motivating elements in my involvement with research on the nature of the observed psychological differences among racial groups. In a recent article (Jensen, 1985b) I stated:I make no apology for my choice of research topics. I think that my own nominal fields of expertise (educational and differential psychology) would be remiss if they shunned efforts to describe and understand more accurately one of the most perplexing and critical of current problems. Of all the myriad subjects being investigated in the behavioral and social sciences, it seems to me that one of the most easily justified is the black- white statistical disparity in cognitive abilities, with its far reaching educational, economic, and social consequences. Should we not apply the tools of our science to such socially important issues as best we can? The success of such efforts will demonstrate that psychology can actually behave as a science in dealing with socially sensitive issues, rather than merely rationalize popular prejudice and social ideology. (p. 258)
    • pp. 438-9
  • Given the present state of our knowledge, and insufficient thought on my part, my own prescription for the time being is to deal as best we can with individual differences and let the statistical group differences fall where they may. Society’s general concern with race and other social group differences is not the product of research on these matters, but arises from chauvinist-like attitudes of racial group identity and solidarity in connection with political power and economic interest. It might be termed meta-racism. The ‘race problem’ from that viewpoint is lower in my own hierarchy of values than concern with individual justice and alleviation of individual misfortune. Though it would be blind not to acknowledge the reality of certain statistical differences among populations, I would find it difficult to be the least concerned with any given individual’s racial heritage. Perhaps I may be too insensitive on this score, never having felt much sense of racial identity myself.
    • p. 443
  • The comments on value-free psychology are so vague as to have no teeth. I wish Sternberg had delivered on whatever point he was trying to make by pointing to some actual examples of how my values (or their lack) have led me to ‘comparisons that should not be made’ or inferences predicated on untrue assumptions. The ‘value-free’ psychology I would advocate is not free of scientific values, or humanistic moral values, or the value of social responsibility, but I do decry the infestation of psychology, or any science, by political and social ideologies. Ideological contamination of psychological research can only make suspect the claim of psychology to scientific status.
    • p. 448

But the most frequently heard objection to further research into human genetics, particularly research into the genetics of behavioral characteristics, is that the knowledge gained might be misused. I agree. Knowledge also, however, makes possible greater freedom of choice. It is a necessary condition for human freedom in the fullest sense. I therefore completely reject the idea that we should cease to discover, to invent, and to know (in the scientific meaning of that term) merely because what we find could be misunderstood, misused, or put to evil and inhumane ends. This can be done with almost any invention, discovery, or addition to knowledge. Would anyone argue that the first caveman who discovered how to make a fire with flint stones should have been prevented from making fire, or from letting others know of his discovery, on the grounds that it could be misused by arsonists? Of course not. Instead, we make a law against arson and punish those who are caught violating the law. The real ethical issue, I believe, is not concerned with whether we should or should not strive for a greater scientific understanding of our universe and of ourselves. For a scientist, it seems to me, this is axiomatic.

1972. Genetics and Education.

We must clearly distinguish between research on racial differ­ences and racism. Racism implies hate or aversion and aims at denying equal rights and opportunities to persons because of their racial origin. It should be attacked by enacting and enforcing laws and arrangements that help to insure equality of civil and political rights and to guard against racial discrimination in educational and occupational opportunities. But to fear research on genetic racial differences, or the possible existence of a biological basis for differences in abilities, is, in a sense, to grant the racist’s assump­tion: that if it should be established beyond reasonable doubt that there are biological or genetically conditioned differences in mental abilities among individuals or groups, then we are justified in oppressing or exploiting those who are most limited in genetic endowment. This is, of course, a complete non sequitur. Equality of human rights does not depend upon the proposition that there are no genetically conditioned individual differences or group differences. Equality of rights is a moral axiom: it does not follow from any set of scientific data.

I have always advocated dealing with persons as individuals, and I am opposed to according differential treatment to persons on the basis of their race, color, national origin, or social-class background. But I am also opposed to ignoring or refusing to investigate the causes of the well-established differences among racial groups in the distribution of educationally relevant traits, particularly IQ. Purely environmental explanations of racial differences in intelli­gence will never gain the status of scientific knowledge unless genetic theories are put to the test and disproved by evidence.

1972. Genetics and Education.

[Interview: Responding to a question about whether it was smart to publish his 1969 article at the time he did] In retrospect, however, I would hope that I would not have changed a thing in that article, even if I had been able to imagine the supposed “storm” it caused. I will be ashamed the day I feel I should knuckle under to social-political pressures about issues and research I think are important for the advance of scientific knowledge.

Profiles in Research Author(s): Arthur Jensen, Daniel H. Robinson and Howard Wainer, Journal of Educational and Behavioral Statistics, Vol. 31, No. 3 (Autumn, 2006), pp. 327-352

I doubt that scientific understanding is advanced by one’s trying to consider every facet of a phenomenon simultaneously and wallowing in the subjective complexity of raw observations. A highly analytical and abstractive approach … will lead to a knowledge of the elements or most fundamental relationships from which we can then reconstruct the full complexity of the phenomenon we had originally set out to study, but now in a way that permits us to understand it in a scientific sense. I find considerable appeal in Newton’s famous motto, ‘Nature is simple’, which I take to mean that relatively simple conceptual relationships can be found within Nature’s phenomenal complexity, and it is the scientist’s job to discover these.


Jensen, A. R. (1984). Jensen oversimplified: A reply to Sternberg. Journal of Social and Biological Structures, 1, 127—130.