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Theory-Testing in Psychology and Physics: A Methodological Paradox

Published online by Cambridge University Press:  14 March 2022

Paul E. Meehl*
Minnesota Center for Philosophy of Science


Because physical theories typically predict numerical values, an improvement in experimental precision reduces the tolerance range and hence increases corroborability. In most psychological research, improved power of a statistical design leads to a prior probability approaching ½ of finding a significant difference in the theoretically predicted direction. Hence the corroboration yielded by “success” is very weak, and becomes weaker with increased precision. “Statistical significance” plays a logical role in psychology precisely the reverse of its role in physics. This problem is worsened by certain unhealthy tendencies prevalent among psychologists, such as a premium placed on experimental “cuteness” and a free reliance upon ad hoc explanations to avoid refutation.

Research Article
Copyright © Philosophy of Science Association 1967

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I wish to express my indebtedness to Dr. David T. Lykken, conversations with whom have played a major role in stimulating my thinking along these lines, and whose views and examples have no doubt influenced the form of the argument in this paper. For an application of these and allied considerations to a specific example of poor research in psychology, see [7].



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