🧠 Crime and Intelligence

Does a person’s intelligence have any correlation to his propensity to commit crime?

One of the first criminologists to study the potential link between crime and intelligence was H. H. Goddard. In his 1914 work Feeble-Mindedness: Its Causes and Consequences, Goddard used one of the earliest standardized IQ tests (designed by French psychologist Alfred Binet) to form conclusions about incarcerated criminals in the U.S. prison system. According to Goddard,

25% to 50% of the people in our prisons are mentally defective and incapable of managing their affairs with ordinary prudence.
Feeble-Mindedness: Its Causes and Consequences (1914)

This, in and of itself, did not cause criminal behavior. However, Goddard believed that if such a person was placed in certain “unwholesome environments,” a high propensity for crime would exist.

Goddard’s conclusions were later refuted by one of the 20^th century’s most influential criminologists: Edwin Sutherland.

Dr. Sutherland rightly pointed out many of the deficiencies in the testing used by Goddard. Though Goddard’s testing methods were questionable, the poor quality of his data did not prove the opposite conclusion, i.e., that there’s no link whatsoever between crime and intelligence.

Nevertheless, that’s how the situation was construed by Sutherland.

As political scientist James Q. Wilson and sociologist Richard J. Herrnstein put it,

[Sutherland] implied that before long it would be obvious to all honest scholars that offenders and nonoffenders did not differ in intelligence.
Crime & Human Nature, p. 153

This belief would pervade criminology and sociology texts for the rest of the 20^th century and continue to the present day.

Again, quoting Wilson and Herrnstein:

Sutherland’s conclusion, though more than half a century old, continues to dominate criminology. Contemporary textbooks often say nothing at all about intelligence, or simply deny its relevance to crime.
Id.

In their book Crime & Human Nature, Wilson and Herrnstein argue that

there appears to be a clear and consistent link between criminality and low intelligence. That is, taking all offenders as a group, and ignoring differences among kinds of crime, criminals seem, on the average, to be a bit less bright and to have a different set of intellectual strengths and weaknesses than do noncriminals as a group.
Id. p. 148

The two academics write that

Reviews of the literature since the 1940s repeatedly place the average offender IQ at about 91-93…On modern intelligence tests, the general population average is fixed at an IQ of 100, but that value reflects all groups, including offenders.
Id. p. 154

After they remove the segment of the population estimated to have a criminal record, the authors “estimate a ten-point [IQ] gap between offenders and nonoffenders.

Another trend is noticeable when the intelligence tests are divided into “performance IQ” (e.g., picture arrangement, block design, object assembly, etc.) and “verbal IQ” (e.g., reading comprehension, vocabulary, word similarities, etc.).

[F]or the average offender, performance IQ was almost eight points higher than verbal IQ.
Id. p. 161

According to the authors, there may be a link between a person’s verbal skills and his “interpersonal maturity” as well as his “moral development.”

They cite studies which show that

[a] deficiency of “internal speech,” or the ability to use language constructively in problem solving, has been a predisposing factor for aggressive behavior in elementary-school children, even after verbal or performance IQ as such is held constant. Such findings make a point worth noting: Measures of intellectual capacity inevitably are associated with other traits that seem more closely tied to personality or temperament, such as the strength of one’s internal monologue.
Id. p. 163

Despite such finds, it is fashionable among criminologists and sociologists to ignore or deny any relation between crime and IQ.

Wilson and Herrstein believe that their colleagues’ unwillingness to accept such a relationship is due to fears of “socioeconomic bias.”

They quote sociology professor Travis Hirschi who said