Smart people are only slightly less criminal: Plato thought that if people broke the law, they did it out of lack of understanding, since men naturally and rationally pursue happiness, and crime only brings misery. He would have predicted a strong inverse correlation between IQ and criminality, but the General Social Survey disagrees with him. I used logistic regression to estimate the relationship between a person's score on a vocabulary test and whether they have ever been arrested (1 for yes, 2 for no). The coefficient for whites is .052, and it's .054 for blacks. In English, what that means is that IQ explains not even close to one percent of criminality. Maybe Plato wanted to see a virtue in people like himself that just isn't there.
In The Bell Curve, the authors state that the average IQ of those who have been interviewed in jail was 90.
ReplyDeletePp. 296-8 of Jensen's _The g Factor_ briefly review the IQ-crime lit. In his Table 9.1 is data from _The Bell Curve_ -- it shows that the percentage of those "ever interviewed in corretional facility (males)" is less than 1%, 1%, 3%, 6%, and 13% for those of IQ above 125, 110-125, 90-110, 75-90, and below 75, respectively.
ReplyDeleteHe also notes that, "Among 1780 enlisted men in the Army, delinquent behavior serious enough for court-martial conviction showed a (biserial) correlation of .31 with the AFQT, a highly g-loaded test. Other studies conducted in the armed forces show a similar relationship between mental test scores and delinquency."
But I think you're right to point to flaws in Plato's reasoning, and the modern version that views the IQ-crime correlation as driven by defects in abstract reasoning per se. I haven't read a lot of this lit, but another (not mutually exclusive) hypothesis is that low IQ results in greater "misfit" status in modern societies, and through repeated failures as well as perhaps envy of those who are smart enough to succeed, lower-IQ people become more likely to say "nuts to the rules" and gain status by illicit means.
For example, Eskimos / Arctic people have a mean IQ of 91, which is about what it is for non-white Hispanics -- except the Eskimos live outside of the modern US society, and thus don't need to complete high school / go to college in order to gain high status, nor are they constantly reminded of their below-Euro-average IQ, since they live in a homogenous area.
And the Amerindians' mean is 86 -- just 1 point above the Af-Am mean, but again they largely live in a separate sphere from the modern US. Australian Aborigenes have the lowest mean IQ at 62, but as I understand, they also live separated from modern Australian society.
I think it's only when low-IQ groups are forced to compete for status in a society that places high demands on intelligence, in particular a society that has a multi-modal IQ distribution so that the lower-mean groups are painfully aware of their disadvantages, that IQ and crime really start to correlate strongly.
dougjnn: I imagine you are right that IQ is more strongly related to serious, chronic offending, but criminologists do not consider arrest a measure of minor offending since police usually don't haul people in for petty crimes.
ReplyDeleteI am somewhat familiar with the research literature, and it shows a consistent but small effect. Researchers often make a big deal about their pet risk factor. The study that Agnostic cites reports a bit larger correlation than what I have usually seen, but even that finding explains less than 10% of the variation in court-martial convictions. The findings I report here are lower than usual, and you might have a point, but keep in mind that speculations can run in the opposite direction too: the correlation might be inflated because smart people are more likely to avoid detection.
For example, when Malcolm X had just burgled a house and was seen by cops on the street, he didn't run. He approached them and asked them a question about directions. Clever.
vic: Of course you are right about racial differences in crime and in IQ, but that does not prove that low IQ is a major determinant of crime. Racial groups differ in many other ways as well (e.g., impulsivity, extraversion, aggressiveness, psychopathy) that might better explain the crime gap.
ReplyDeletegreat article. I would love to follow you on twitter.
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