Race and intelligence
October 5th 2007 07:59
This is a bit lengthy. But couldn't do any sort of justice with a shorter post, so...
For the record, my personal take is simply to avoid using the word "intelligence" (along with other dust-binned words -- "democracy", "love", "philosophy", etc). I think that as a natural-language term it's hopelessly vague; and that, as a purported scientific term, all that IQ really measures is aptitude at IQ tests.
From the introduction to a 1990 bibliography of IQ literature: The IQ Debate, compiled by Stephen H Aby.
Overview of the IQ Debate
History
The arguments that differences in intelligence are inherited, and that races, classes, and ethnic groups differ in their average levels of intelligence, are not new. In 1869 Sir Francis Galton, in Hereditary Genius, made the first effort... He studied relatives of Britain's elite, and... found that they too were likely to be among the elite. This indicated to him that ability was inherited. Today it is clear that his explanation... overlooked environmental factors... [Wikipedia seems to disagree with the "first effort" credit: "Theories about the possibility of a relationship between race and intelligence have been the subject of speculation and debate since the 16th century."]
Alfred Binet is credited with developing the first successful intelligence test in France in 1905. Interestingly, however... [t]here was no suggestion on Binet's part that the test measured the child's innate capacity or ability; in fact, he was critical of the "brutal pessimism" of such an idea...
It was not until Binet's test was introduced in the United States, between 1908 and 1920, by Lewis Terman, Henry Goddard, and Robert Yerkes that it was interpreted as a measure of innate intelligence... [T]he testing of immigrants at Ellis Island in New York and of American soldiers in World War I helped to legitimize both the intelligence test and the field of psychology. The findings from these testing efforts confirmed for these early mental testers that certain racial, ethnic, and immigrant groups were intellectually inferior. These results... contributed to the passage of the racist Immigration Restriction Act of 1924...
In this period, the IQ debate surfaced in its earliest public forum. Lewis Terman and Walter Lippmann, in a series of popular magazine articles in the 1920s, engaged in a debate... [Lippmann's] critique foreshadowed many of the [later] arguments... For example, he accused the mental testers of a misunderstanding of the concept of mental age and of attributing to it a fixedness that violated Binet's intent. Lippmann also raised questions about the representativeness of the American population sample (400 Californians) on which Binet's test was standardized for American use. He questioned further whether the testers even knew what intelligence was and criticized their willingness to believe in it simply because they had test scores for it. He also examined biases in the test's construction, as well as its poor correlation with other indicators of success.
... All of these historical threads became newly relevant when Arthur Jensen published his controversial article ["How much can we boost IQ and scholastic achievement?", Harvard Educational Review, Winter 1969]...
The Current Debate
Much of Jensen's article was a summary and analysis of previous research. In particular, he focused on studies of identical twins reared apart... kinship correlations, and adoption studies... If the twins showed significantly similar IQ scores, despite being raised in different environments, this would indicate, he felt, that one's intellectual ability was determined primarily by genetic endowment. Similarly, with the kinship correlations, if the scores of closely related individuals were more highly correlated than those of distant relatives... Adoption studies, too, were considered useful... If, despite their rearing environment, the IQs of adopted children were less like those of their adopted siblings and parents and more like their natural parents...
After reviewing this and other research, Jensen suggested that intelligence is 80% heritable; that is, 80% of the differences among individual IQ scores in a population is attributable to genes, not environment... Jensen argued further that blacks and whites differed in the way they were best able to learn. Blacks and whites were comparable in associative or rote learning abilities, while whites were superior in cognitive or abstract learning abilities. He indicated that schools would be more successful if they taught students in a manner consistent with their learning styles.
[...]
The controversy has continued unabated since the early 1970s... Jensen has since argued that certain physiological measures, such as "evoked potentials" (brain wave activity) or choice reaction time... correlate with intelligence measures. This, he argues, indicates that intelligence differences are innate and physiologically based.
Some of Jensen's supporters have generated their own controversy. For example... Richard Herrnstein argued that poor people in general, regardless of race, were less intelligent than the rich... William Shockley, the late Nobel-prize-winning physicist... argued that women on welfare should be offered cash incentives to undergo sterilization...
The Critics
Critics have attacked IQ theory for a variety of reasons. Some attack the very motivation for conducting such research...
Others [sic] critics have attacked the quality of the research on IQ, disputing the methodological soundness of the key studies... and the cultural fairness of the IQ tests... According to critics such as Leon Kamin... twins are often raised in environments too similar to separate out genetic versus environmental causes for their similar scores. Even more spectacularly, Kamin and others have demonstrated that much of the twin data published by Sir Cyril Burt were fraudulent...
Of course, the argument... presumes that we know what intelligence is and how to measure it. Some critics accept neither of these propositions... [D]o people possess a variety of intelligences... Furthermore, is intelligence an innate entity or thing that can be identified and measured, or is it a collection of behaviors that are defined as intelligent by one's culture?...
In response, hereditarians ask how environmentalists can explain the fact that middle-class blacks still score worse than middle-class whites, and that American Indians, who are more impoverished than blacks, do better on intelligence tests... Critics state that... while American Indians are poorer than blacks, do we know that this is the only relevant environmental difference... It is this inadequacy of our understanding that has prompted research into more subtle environmental factors by such critics as Jane Mercer, Zena Blau, and Elsie Moore.
Another focus for the critics is Arthur Jensen's assumption that compensatory education has failed... The critics question whether, in fact, compensatory programs have ever been sufficiently attempted...
Still other critics challenge... the assumption that intelligence is a key determinant of success in school and life... Samuel Bowles and Herbert Gintis, for example, argue that it is one's social class background... that is most determinative of one's success. Other critics [ask]... Even if individuals do inherit different levels of intelligence, why do they have to receive unequal social rewards as a result?...
The response of the hereditarians... has been varied. In many cases, they have responded to substantive criticisms in kind... They have also, on occasion, accused their critics of censorship and violations of academic freedom... [They say] research into intelligence differences is a legitimate subject of inquiry, and it should be evaluated on its scientific, not ideological, merits. Again, however, the issues are not quite so clear cut. Some critics, such as Steven Selden, argue that the selection of "problems" for research is influenced by one's values and ideologies...
So there was the Jensen controversy of the early 70s. But public engagement with these issues has also been sparked by, inter alia: --
-- Stephen Jay Gould's 1981 book, The Mismeasure of Man, which "skeptically investigates 'the abstraction of intelligence as a single entity, its location within the brain, its quantification as one number for each individual, and the use of these numbers to rank people in a single series of worthiness, invariably to find that oppressed and disadvantaged groups -- races, classes, or sexes -- are innately inferior and deserve their status.'"
-- The 1994 book The Bell Curve, by Richard J Herrnstein and Charles Murray. "Its central point is that intelligence is a better predictor of many factors including financial income, job performance, unwed pregnancy, and crime than parent's Socio-Economic status or education level... Much of the controversy erupted from Chapters 13 and 14, where the authors write about the enduring differences in race and intelligence... The authors were reported throughout the popular press as arguing that these IQ differences are genetic, although they state no position on the issue in the book, and write in the introduction to Chapter 13 that 'The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved.'"
-- In Finland in 2004, the comments of Tatu Vanhanen, father of Prime Minister Matti Vanhanen that: "Whereas the average IQ of Finns is 97, in Africa it is between 60 and 70. Differences in intelligence are the most significant factor in explaining poverty".
-- In Australia in 2005, the letter of Andrew Fraser (printed below), and his essay "Rethinking the White Australia Policy", in which he claimed, among other things, that African immigration should be restricted because "[e]xperience practically everywhere in the world tells us that an expanding black population is a sure-fire recipe for increases in crime, violence and a wide range of other social problems", and Asian immigration should be restricted because "Endowed with an edge in IQ and a temperament conducive to rigorous regimes of coaching, rote learning and stricter parental discipline, young East Asians already dominate the competition for places in universities and professional schools. Within two to three decades, it is not unreasonable to expect that Australia will have a heavily Asian managerial-professional, ruling class that will not hesitate to promote the interests of co-ethnics at the expense of white Australians."
-- In October 2007, James Watson's remarks to the British Sunday Time Magazine about the possibility that Africans are genetically of lower intelligence, which included the comments: "all our social policies are based on the fact that their intelligence is the same as ours -- whereas all the testing says not really", and "there are many people of colour who are very talented, but don’t promote them when they haven’t succeeded at the lower level". A remark in his book, Avoid boring people: lessons from a life in science (2007), was also widely reported: "There is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically. Our wanting to reserve equal powers of reason as some universal heritage of humanity will not be enough to make it so."
Peter Singer's comments from Practical Ethics (1993) are worth quoting: --
In 1969 Arthur Jensen published a long article in the Harvard Educational Review... One short section... discussed the probable causes of the undisputed fact that -- on average -- African Americans do not score as well as most other Americans in standard IQ tests. Jensen summarised the upshot of this section as follows:
Andrew Fraser's essay on "Rethinking the White Australia Policy" is available online, but the letter that sparked the whole controversy, published in the Parramatta Sun, might be harder to track down. Here's a copy: --
The Path to National Suicide
Now that a large number of Sudanese refugees have been settled in the Parramatta-Blacktown area, Anglo-Australians are once again expected to acquiesce in the steady erosion of their distinctive national identity.
Australia, it seems, can no longer remain the homeland of a particular people. Instead, it must become a colony of the Third World.
Thirty years ago, no one in the world had any difficulty identifying an Australian. Today, if the headline in the Sun is to be believed, black Africans and Muslim Afghanis “are Aussies just like” the descendants of the Anglo-Celtic pioneers who settled and built this country.
Community Relations Commissioner Stepan Kerkyasharian declares that “Australians... have a responsibility” to help those on the losing side in Third World civil wars to settle here, wherever and whenever it suits governments and the ever-expanding refugee industry. He assures us that the ethnic and religious conflicts endemic to every other part of the world will be magically dissolved by the state-enforced “commonality of Australianism.”
That utopian fantasy is particularly likely to unravel as local African tribal groups grow in size and confidence. Experience practically everywhere in the world tells us that an expanding black population is a sure-fire recipe for increases in crime, violence and a wide range of other social problems.
The fact is that ordinary Australians are being pushed down the path to national suicide by their own political, religious and economic élites. Shutting our eyes to that fact will not make it go away.
Some further (rather dodgy) reading:
-- Wikipedia article on criticism of IQ measurement
-- Wikipedia article on race and intelligence
For the record, my personal take is simply to avoid using the word "intelligence" (along with other dust-binned words -- "democracy", "love", "philosophy", etc). I think that as a natural-language term it's hopelessly vague; and that, as a purported scientific term, all that IQ really measures is aptitude at IQ tests.
***
From the introduction to a 1990 bibliography of IQ literature: The IQ Debate, compiled by Stephen H Aby.
Overview of the IQ Debate
History
The arguments that differences in intelligence are inherited, and that races, classes, and ethnic groups differ in their average levels of intelligence, are not new. In 1869 Sir Francis Galton, in Hereditary Genius, made the first effort... He studied relatives of Britain's elite, and... found that they too were likely to be among the elite. This indicated to him that ability was inherited. Today it is clear that his explanation... overlooked environmental factors... [Wikipedia seems to disagree with the "first effort" credit: "Theories about the possibility of a relationship between race and intelligence have been the subject of speculation and debate since the 16th century."]
Alfred Binet (1857-1911)
It was not until Binet's test was introduced in the United States, between 1908 and 1920, by Lewis Terman, Henry Goddard, and Robert Yerkes that it was interpreted as a measure of innate intelligence... [T]he testing of immigrants at Ellis Island in New York and of American soldiers in World War I helped to legitimize both the intelligence test and the field of psychology. The findings from these testing efforts confirmed for these early mental testers that certain racial, ethnic, and immigrant groups were intellectually inferior. These results... contributed to the passage of the racist Immigration Restriction Act of 1924...
In this period, the IQ debate surfaced in its earliest public forum. Lewis Terman and Walter Lippmann, in a series of popular magazine articles in the 1920s, engaged in a debate... [Lippmann's] critique foreshadowed many of the [later] arguments... For example, he accused the mental testers of a misunderstanding of the concept of mental age and of attributing to it a fixedness that violated Binet's intent. Lippmann also raised questions about the representativeness of the American population sample (400 Californians) on which Binet's test was standardized for American use. He questioned further whether the testers even knew what intelligence was and criticized their willingness to believe in it simply because they had test scores for it. He also examined biases in the test's construction, as well as its poor correlation with other indicators of success.
... All of these historical threads became newly relevant when Arthur Jensen published his controversial article ["How much can we boost IQ and scholastic achievement?", Harvard Educational Review, Winter 1969]...
Arthur Jensen (1923-)
Much of Jensen's article was a summary and analysis of previous research. In particular, he focused on studies of identical twins reared apart... kinship correlations, and adoption studies... If the twins showed significantly similar IQ scores, despite being raised in different environments, this would indicate, he felt, that one's intellectual ability was determined primarily by genetic endowment. Similarly, with the kinship correlations, if the scores of closely related individuals were more highly correlated than those of distant relatives... Adoption studies, too, were considered useful... If, despite their rearing environment, the IQs of adopted children were less like those of their adopted siblings and parents and more like their natural parents...
After reviewing this and other research, Jensen suggested that intelligence is 80% heritable; that is, 80% of the differences among individual IQ scores in a population is attributable to genes, not environment... Jensen argued further that blacks and whites differed in the way they were best able to learn. Blacks and whites were comparable in associative or rote learning abilities, while whites were superior in cognitive or abstract learning abilities. He indicated that schools would be more successful if they taught students in a manner consistent with their learning styles.
[...]
The controversy has continued unabated since the early 1970s... Jensen has since argued that certain physiological measures, such as "evoked potentials" (brain wave activity) or choice reaction time... correlate with intelligence measures. This, he argues, indicates that intelligence differences are innate and physiologically based.
Some of Jensen's supporters have generated their own controversy. For example... Richard Herrnstein argued that poor people in general, regardless of race, were less intelligent than the rich... William Shockley, the late Nobel-prize-winning physicist... argued that women on welfare should be offered cash incentives to undergo sterilization...
The Critics
Critics have attacked IQ theory for a variety of reasons. Some attack the very motivation for conducting such research...
'Mensa has three stated purposes: to identify and foster human intelligence for the benefit of humanity, to encourage research in the nature, characteristics and uses of intelligence, and to promote stimulating intellectual and social opportunities for its members.' (It's best at the last one.)
Of course, the argument... presumes that we know what intelligence is and how to measure it. Some critics accept neither of these propositions... [D]o people possess a variety of intelligences... Furthermore, is intelligence an innate entity or thing that can be identified and measured, or is it a collection of behaviors that are defined as intelligent by one's culture?...
In response, hereditarians ask how environmentalists can explain the fact that middle-class blacks still score worse than middle-class whites, and that American Indians, who are more impoverished than blacks, do better on intelligence tests... Critics state that... while American Indians are poorer than blacks, do we know that this is the only relevant environmental difference... It is this inadequacy of our understanding that has prompted research into more subtle environmental factors by such critics as Jane Mercer, Zena Blau, and Elsie Moore.
Another focus for the critics is Arthur Jensen's assumption that compensatory education has failed... The critics question whether, in fact, compensatory programs have ever been sufficiently attempted...
Still other critics challenge... the assumption that intelligence is a key determinant of success in school and life... Samuel Bowles and Herbert Gintis, for example, argue that it is one's social class background... that is most determinative of one's success. Other critics [ask]... Even if individuals do inherit different levels of intelligence, why do they have to receive unequal social rewards as a result?...
The response of the hereditarians... has been varied. In many cases, they have responded to substantive criticisms in kind... They have also, on occasion, accused their critics of censorship and violations of academic freedom... [They say] research into intelligence differences is a legitimate subject of inquiry, and it should be evaluated on its scientific, not ideological, merits. Again, however, the issues are not quite so clear cut. Some critics, such as Steven Selden, argue that the selection of "problems" for research is influenced by one's values and ideologies...
***
So there was the Jensen controversy of the early 70s. But public engagement with these issues has also been sparked by, inter alia: --
Stephen Jay Gould (1941-2002)
-- The 1994 book The Bell Curve, by Richard J Herrnstein and Charles Murray. "Its central point is that intelligence is a better predictor of many factors including financial income, job performance, unwed pregnancy, and crime than parent's Socio-Economic status or education level... Much of the controversy erupted from Chapters 13 and 14, where the authors write about the enduring differences in race and intelligence... The authors were reported throughout the popular press as arguing that these IQ differences are genetic, although they state no position on the issue in the book, and write in the introduction to Chapter 13 that 'The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved.'"
-- In Finland in 2004, the comments of Tatu Vanhanen, father of Prime Minister Matti Vanhanen that: "Whereas the average IQ of Finns is 97, in Africa it is between 60 and 70. Differences in intelligence are the most significant factor in explaining poverty".
-- In Australia in 2005, the letter of Andrew Fraser (printed below), and his essay "Rethinking the White Australia Policy", in which he claimed, among other things, that African immigration should be restricted because "[e]xperience practically everywhere in the world tells us that an expanding black population is a sure-fire recipe for increases in crime, violence and a wide range of other social problems", and Asian immigration should be restricted because "Endowed with an edge in IQ and a temperament conducive to rigorous regimes of coaching, rote learning and stricter parental discipline, young East Asians already dominate the competition for places in universities and professional schools. Within two to three decades, it is not unreasonable to expect that Australia will have a heavily Asian managerial-professional, ruling class that will not hesitate to promote the interests of co-ethnics at the expense of white Australians."
-- In October 2007, James Watson's remarks to the British Sunday Time Magazine about the possibility that Africans are genetically of lower intelligence, which included the comments: "all our social policies are based on the fact that their intelligence is the same as ours -- whereas all the testing says not really", and "there are many people of colour who are very talented, but don’t promote them when they haven’t succeeded at the lower level". A remark in his book, Avoid boring people: lessons from a life in science (2007), was also widely reported: "There is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically. Our wanting to reserve equal powers of reason as some universal heritage of humanity will not be enough to make it so."
***
Peter Singer's comments from Practical Ethics (1993) are worth quoting: --
In 1969 Arthur Jensen published a long article in the Harvard Educational Review... One short section... discussed the probable causes of the undisputed fact that -- on average -- African Americans do not score as well as most other Americans in standard IQ tests. Jensen summarised the upshot of this section as follows:
| All we are left with are various lines of evidence, no one of which is definitive alone, but which, viewed together, make it a not unreasonable hypothesis that genetic factors are strongly implicated in the average negro-white intelligence difference. The preponderance of evidence is, in my opinion, less consistent with a strictly environmental hypothesis than with a genetic hypothesis, which, of course, does not exclude the influence of environment or its interaction with genetic factors. |
This heavily qualified statement comes in the midst of a detailed review of a complex scientific subject, published in a scholarly journal. It would hardly have been surprising if it passed unnoticed by anyone but scientists working in the area of psychology or genetics. Instead it was widely reported in the popular press as an attempt to defend racism on scientific grounds. Jensen was accused of spreading racist propaganda and likened to Hitler. His lectures were shouted down [an experience Singer himself is no stranger to] and students demanded that he be dismissed from his university post. HJ Eysenck, a British professor of psychology who supported Jensen's theories received similar treatment... Interestingly, Eysenck's argument did not suggest that those of European descent have the highest average intelligence among Americans; instead, he noted some evidence that Americans of Japanese and Chinese descent do better on tests of abstract reasoning...
[...]
Let us suppose, just for the sake of exploring the consequences, that evidence accumulates supporting the hypothesis that there are differences in intelligence between the different ethnic groups... What significance would this have for our views about racial equality?
First a word of caution. When people talk of differences in intelligence between ethnic groups, they are usually referring to difference in scores on standard IQ tests. Now "IQ" stands for "intelligence quotient" but this does not mean that an IQ test really measures what we mean by "intelligence" in ordinary contexs. Obviously there is some correlation... But this does not show how close the correlation is, and since our ordinary concept of intelligence is vague, there is no way of telling...
When people of different racial origins are given IQ tests, there tend to be differences in the average scores they get. The existence of such differences is not seriously disputed... What is hotly disputed is whether the differences are primarily to be explained by heredity or by environment...
Let us suppose that the genetic hypothesis turns out to be correct... I believe that the implications of this supposition are less drastic than they are often supposed to be...
First, the genetic hypothesis does not imply that we should reduce our efforts to overcome other causes of inequality between people... Perhaps we should put special efforts into helping those who start from a position of disadvantage, so that we end with a more egalitarian result.
Second, the fact that the average IQ of one racial group is a few points higher than that of another does not allow anyone to say that all members of the higher IQ group have higher IQs... The point is that these figures are averages and say nothing about individuals...
The third reason... is simply that, as we saw earlier, the principle of equality is not based on any actual equality that all people share. I have argued that the only defensible basis for the principle of equality is equal consideration of interests... Equal status does not depend on intelligence. Racists who maintain the contrary are in peril of being forced to kneel before the next genius they encounter.
***
Andrew Fraser's essay on "Rethinking the White Australia Policy" is available online, but the letter that sparked the whole controversy, published in the Parramatta Sun, might be harder to track down. Here's a copy: --
Andrew Fraser
Now that a large number of Sudanese refugees have been settled in the Parramatta-Blacktown area, Anglo-Australians are once again expected to acquiesce in the steady erosion of their distinctive national identity.
Australia, it seems, can no longer remain the homeland of a particular people. Instead, it must become a colony of the Third World.
Thirty years ago, no one in the world had any difficulty identifying an Australian. Today, if the headline in the Sun is to be believed, black Africans and Muslim Afghanis “are Aussies just like” the descendants of the Anglo-Celtic pioneers who settled and built this country.
Community Relations Commissioner Stepan Kerkyasharian declares that “Australians... have a responsibility” to help those on the losing side in Third World civil wars to settle here, wherever and whenever it suits governments and the ever-expanding refugee industry. He assures us that the ethnic and religious conflicts endemic to every other part of the world will be magically dissolved by the state-enforced “commonality of Australianism.”
That utopian fantasy is particularly likely to unravel as local African tribal groups grow in size and confidence. Experience practically everywhere in the world tells us that an expanding black population is a sure-fire recipe for increases in crime, violence and a wide range of other social problems.
The fact is that ordinary Australians are being pushed down the path to national suicide by their own political, religious and economic élites. Shutting our eyes to that fact will not make it go away.
***
Some further (rather dodgy) reading:
-- Wikipedia article on criticism of IQ measurement
-- Wikipedia article on race and intelligence
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Comment by Nonymous
Philosophy Blog
Will have to blog about race in a future post.
Comment by Damo
This is a long and difficult subject and prbably has the interest of many people.
Just a few notes:
The book called 'The Bell Curve' did hve an impact upon opinions in the US and even Pres Clinton refered to it at one stage as showing troubling warning signs. (I asume it was an off the cuff remark)
Yet there is more to the book and its backers than just objective research. Its sponsors and backers do come from societies that are pro-race difference.
I have the a copy of 'The Bell Curve Debate' as one of my main reference books. It is a very good analisys and disection of the 'Bell Curve' thesis. It also looks at the raw data that used to prove the arguements.
An a more practical side there is not one IQ test but many IQ tests, each testing something subtly different about intelligence. Averaging this data into a bell curve graph is problematic and can often force the compiler to select the evidence to match the argument. (Accademics cheating? never!)
In professional experience I have seen engineers compile data to favour their proposal. When compared step by step to complete data they sometimes get offended. (All that creative effort shot down by an ugly gang of facts)
This post is timely as the current debate about African Refugees heats up. I do expect to see many of the same arguments used in the 'Bell Curve' et al to be thrown into the public arena.
I leave questioning the validity of IQ testing for another time as it is a big subject.
Comment by Brenton
Dr Spin
Tales From The Other Side
Blip Blog
Gadget Museum
Comment by Nonymous
Philosophy Blog
I suppose I'd add to this that the idea of breaking g into different intelligences is not uncommon.
For instance, from a recent book review:
Dear Brenton,
Putting aside the question of how to define a race, which is a lot more problematic than I've made out...
Are there differences in genetic intelligence (treating "intelligence" as ability to perform well on IQ tests)? Well, I have to give you the cop out answer -- I just don't know; and there doesn't, at least from my brief reading, seem to be a clear consensus (as there might be for an issue like global warming). So I suspend judgment.
Are there difference in "style"? Well, depends what you mean by style, of course. But I don't doubt that different cultures develop different brains. For instance, if your educational system drills you more in maths, then (I'd claim) you're obviously going to score better on the maths components of IQ tests. And I don't doubt that one culture might be more visual than another, and one culture might be more aural than another, and so forth. -- I do think there is sufficient to establish these, as you put it. But my claims here are ultimately simply assertions, and they're based not on psych studies, but on the woolly grounds of personal experience and appeals to the reader's experience ("Consult yourself, and see if this is not true, or at least plausible").