Quantification in Psychology: Critical Analysis of an Unreflective Practice

It is common practice in psychology to presume that phenomena of interest can and should be represented numerically, and that inferences should be based on mathematical analysis of those numerical representations. In this article, we question the dominance of quantification (i.e., numerical representation) in psychological research practice. Drawing from the history of quantification in modern psychology, we argue that the motivation for quantifying information in psychology has centered on 4 related and often implicit factors: (a) quantification to ensure objectivity, precision, and rigor; (b) the quantitative imperative (Michell, 2003); (c) the perceived need for statistical inference (i.e., statisticism; Lamiell, 2010, 2013b); and (d) philosophical assumptions. We review several critical arguments put forth from theoretical psychologists, as well as from philosophers and historians of psychology, against each of these underlying motives. Based on our review, we argue that the limitations of quantification are in direct conflict with the motives that drive its use. We further argue that this is primarily because quantification in psychology has historically been, and continues to be, a generally unreflective practice. To remedy this unreflective reliance on quantification, we suggest that psychology embrace a tradition of greater critical reflection in which research aims are prioritized.