In psychology and criminology, Differential ''K'' theory is a debunked hypothesis first proposed by Canadian psychologist

J. Philippe Rushton John Philippe Rushton (December 3, 1943 – October 2, 2012) was a Canadian psychologist and author. He taught at the University of Western Ontario until the early 1990s, and became known to the general public during the 1980s and 1990s for rese ...

in 1985, which attempts to apply ''r''/''K'' selection theory to

human races A race is a categorization of humans based on shared physical or social qualities into groups generally viewed as distinct within a given society. The term came into common usage during the 1500s, when it was used to refer to groups of variou ...

. According to Rushton, this theory explains race differences in fertility, IQ, criminality, and sexual anatomy and behavior. The theory also hypothesizes that a single factor, the "''K'' factor", affects multiple population statistics Rushton referred to as "life-history traits". It has been criticized as a key example of

scientific racism Scientific racism, sometimes termed biological racism, is the pseudoscientific belief that empirical evidence exists to support or justify racism ( racial discrimination), racial inferiority, or racial superiority.. "Few tragedies can be more ...

and devoid of empirical basis.

History

A 2013 study found tentative support for some aspects of the theory, specifically the correlative relationships between IQ and parental investment along with fertility rates. However, the authors noted that, after accounting for the proportion of black residents among counties, no association was observed between IQ and either life-history variable. Some researchers have also tried to combine differential ''K'' theory with

Terrie Moffitt's developmental theory of crime In 1993, American psychologist Terrie Moffitt described a dual taxonomy of offending behavior in an attempt to explain the developmental processes that lead to the distinctive shape of the age crime curve. Moffitt proposed that there are two main ...

to create what they call a "unified crime theory".

Reception

Andrew Winston Andrew Spencer Winston (born 1946) is a psychologist and historian who is an emeritus professor at the University of Guelph in Canada. He is known for his research on the history of scientific racism and eugenics in psychology. He was president o ...

summarizes, "Rushton's work was heavily criticized by psychologists, evolutionary biologists, anthropologists, and geneticists for severe scientific inadequacies, fundamental errors, inappropriate conceptualization of race, inappropriate statistical comparisons, misuse of sources, and serious logical errors and flaws." Differential K theory in particular was described in a 2020 statement by Rushton's former department at

Western Ontario University The University of Western Ontario (UWO), also known as Western University or Western, is a public research university in London, Ontario, Canada. The main campus is located on of land, surrounded by residential neighbourhoods and the Thames Ri ...

as "thoroughly debunked." Weizmann et al. argued that Rushton attempted to validate this hypothesis by use of "selective citation and misrepresentation of the research literature and by the use of unreliable sources" and that Rushton's methodology "indicates a lack of familiarity with ecological thinking and scientific method in general." A 2014 study found differences in the General Factor of Personality across races that were not compatible with differential ''K'' theory. Additional criticism of the theory has come from Edward M. Miller, who has argued that contrary to the theory, unpredictable environments select for ''K'', not ''r'' characteristics.

References

Psychological theories Race and intelligence controversy {{Psychology-stub