Paul E. Meehl
Paul Everett Meehl was an American clinical psychologist. He was the Hathaway and Regents' Professor of Psychology at the University of Minnesota, and past president of the American Psychological Association. A Review of General Psychology survey, published in 2002, ranked Meehl as the 74th most cited psychologist of the 20th century, in a tie with Eleanor J. Gibson. Throughout his nearly 60-year career, Meehl made seminal contributions to psychology, including empirical studies and theoretical accounts of construct validity, schizophrenia etiology, psychological assessment, behavioral prediction, metascience, and philosophy of science.
Biography
Childhood
Paul Meehl was born January 3, 1920, in Minneapolis, Minnesota, to Otto and Blanche Swedal. His family name "Meehl" was his stepfather's. When he was age 16, his mother died as the result of poor medical care which, according to Meehl, greatly affected his faith in the expertise of medical practitioners and diagnostic accuracy of clinicians. After his mother's death, Meehl lived briefly with his stepfather, then with a neighborhood family for one year so he could finish high school. He then lived with his maternal grandparents, who lived near the University of Minnesota.Education and academic career
Meehl started as an undergraduate at the University of Minnesota in March 1938. He earned his bachelor's degree in 1941 with Donald G. Paterson as his advisor, and took his PhD in psychology at Minnesota under Starke R. Hathaway in 1945. Meehl's graduate student cohort at the time included Marian Breland Bailey, William K. Estes, Norman Guttman, William Schofield, and Kenneth MacCorquodale. Upon taking his doctorate, Meehl immediately accepted a faculty position at the university, which he held throughout his career. In addition, he had appointments in psychology, law, psychiatry, neurology, philosophy, and served as a fellow of the Minnesota Center for Philosophy of Science, founded by Herbert Feigl, Meehl, and Wilfrid Sellars.Meehl rose quickly to academic positions of prominence. He was chairman of the University of Minnesota Psychology Department at age 31, president of the Midwestern Psychological Association at age 34, recipient of the American Psychological Association's Award for Distinguished Scientific Contributions to Psychology at age 38, and president of that association at age 42. He was promoted to Regents' professor, the highest academic position at the University of Minnesota, in 1968. He received the Bruno Klopfer Distinguished Contributor Award in personality assessment in 1979, and was elected to the National Academy of Sciences in 1987.
Meehl was not particularly religious during his upbringing, but in adulthood during the 1950s collaborated with a group of Lutheran theologians and psychologists to write What, Then, Is Man?. This project was commissioned by the Lutheran Church–Missouri Synod through Concordia Seminary. The project explored both orthodox theology, psychological science, and how Christians could responsibly function as both Christians and psychologists without betraying orthodoxy or sound science and practice.
Later life and death
In 1995, Meehl was a signatory of a collective statement titled "Mainstream Science on Intelligence", written by Linda Gottfredson and published in the Wall Street Journal. He died on February 14, 2003, at his home in Minneapolis of chronic myelomonocytic leukemia. In 2005, Donald R. Peterson, a student of Meehl's, published a volume of their correspondence.Philosophy of science
Meehl founded, along with Herbert Feigl and Wilfrid Sellars, the Minnesota Center for the Philosophy of Science, and was a leading figure in philosophy of science as applied to psychology.Arguably Meehl's most important contributions to psychological research methodology were in legitimizing scientific claims about unobservable psychological processes. In the first half of the 20th century, psychology was dominated by operationism and behaviorism. As outlined in Bridgman's The Logic of Modern Physics, if two researchers had different operational definitions, they had different concepts. There was no "surplus meaning". If, for example, two researchers had different measures of "anomia" or "intelligence", they had different concepts. Behaviorists focussed on stimulus–response theories and were deeply skeptical of "unscientific" explanations in terms of unobservable psychological processes. Behaviorists and operationists would have rejected as unscientific any notion that there was some general thing called "intelligence" that existed inside a person's head and that might be reflected almost-equivalently in Stanford-Binet IQ tests or Wechsler scales. Meehl changed that via two landmark papers.
In 1948, Kenneth MacCorquodale and Meehl introduced the distinction between "hypothetical construct" and "intervening variable". "Naively, it would seem that there is a difference in logical status between constructs which involve the hypothesization of an entity, process, or event which is not itself observed, and constructs which do not involve such hypothesization." An intervening variable is simply a mathematical combination of operations. If one speaks of the "expected value" of a gamble, this is not hypothesizing any unobservable psychological process. Expected value is simply a mathematical combination of observables. On the other hand, if one attempts to make statements about "attractiveness" of a gamble, if this is not observable or perfectly captured by some single operational measure, this is a "hypothetical construct"—a theoretical term that is not itself observable or a direct function of observables. They used as examples Hull's or Allport's "biophysical traits", or Murray's "needs". "These constructs involve terms which are not wholly reducible to empirical terms; they refer to processes or entities that are not directly observed." Such constructs had "surplus meaning". Thus, good behaviorists and operationists should be comfortable with statements about intervening variables, but should have greater wariness of hypothetical constructs.
Construct validity and nomological networks
In 1955, Lee J. Cronbach and Meehl legitimized theory tests about unobservable, hypothetical constructs. Constructs are unobservables, and they can be stable traits of individuals or temporary states. Previously, good behaviorists had deep skepticism about the legitimacy of psychological research about unobservable processes. Cronbach and Meehl introduced the concept of "construct" validity for cases in which there was no "gold standard" criterion for validating a test of a hypothetical construct. Hence, any construct had "surplus meaning". Construct validity was distinguished from predictive validity, concurrent validity, and content validity. They also introduced the concept of the "nomological net"—the network of associations among constructs and measures. Cronbach and Meehl argued that the meaning of a hypothetical construct is given by its relations to other variables in a nomological network. One tests a theory of relations among hypothetical constructs by showing that putative measures of these constructs relate to each other as implied by one's theory, as captured in the nomological network. This set the stage for modern psychological test and set the stage for the cognitive revolution in psychology that focusses on the study of mental processes that are not directly observable.Criticism of null hypothesis testing
After Karl Popper's The Logic of Scientific Discovery was published in English in 1959, Meehl counted himself a "Popperian" for a short time, later as "a 'neo-Popperian' philosophical eclectic", still using the Popperian approach of conjectures and refutations, but without endorsing all of Popper's philosophy. Influenced by and in respect of Popper's asymmetry principle, Meehl was a strident critic of using statistical null hypothesis testing for the evaluation of scientific theory. He believed that null hypothesis testing was partly responsible for the lack of progress in many of the "scientifically soft" areas of psychology. At the same time, although Meehl harshly criticized the overreliance of psychology on null hypothesis significance testing, he also noted, “When I was arat psychologist, I unabashedly employed significance
testing in latent-learning experiments; looking back I
see no reason to fault myself for having done so in the
light of my present methodological views”. He mainly promoted a switch to interval hypothesis testing.