Quantitative science and the definition of measurement in psychology

Abstract

It is argued that establishing quantitative science involves two research tasks: the scientific one of showing that the relevant attribute is quantitative; and the instrumental one of constructing procedures for numerically estimating magnitudes. In proposing quantitative theories and claiming to measure the attributes involved, psychologists are logically committed to both tasks. However, they have adopted their own, special, definition of measurement, one that deflects attention away from the scientific task. It is argued that this is not accidental. From Fechner onwards, the dominant tradition in quantitative psychology ignored this task. Stevens' definition rationalized this neglect. The widespread acceptance of this definition within psychology made this neglect systemic, with the consequence that the implications of contemporary research in measurement theory for undertaking the scientific task are not appreciated. It is argued further that when the ideological support structures of a science sustain serious blind spots like this, then that science is in the grip of some kind of thought disorder. …unluckily our professors of psychology in general are not up to quantitative logic… E. L. Thorndike to J. McK. Cattell, 1904