130 Agnes Petocz
summarise Michell's arguments, psychology's commitment to the "quantitative imperative"
(the view that measurement is a necessary condition of science) has led to an approach to
measurement and quantitative methods which constitutes a "pathology of science", a form of
"methodological thought-disorder" (Michell, 1997). This involves a two-stage breakdown in
scientific practice. At the first stage, the underlying empirical hypothesis that the
psychological attribute being assessed is quantitative is not subject to empirical test. In other
words, psychology merely assumes that its variables of interest (abilities, intelligence,
attitudes, personality traits, etc.) are indeed quantitative and hence measurable. At the second
stage, this failure to test the empirical hypothesis is then disguised. The disguise is effected by
abandoning the classical realist definition of measurement which informs measurement in the
physical sciences, namely, that measurement is the "assessment of the magnitude of a level of
an attribute via its numerical relation (ratio) to another level of the same attribute (the unit
selected)" (Michell, 2001, p. 212). In place of this realist definition, which faithfully reflects
the fact that measurement requires quantitative structure, psychology has adopted its own
special definition of measurement (following S. S. Stevens, 1946), according to which
measurement is the "assignment of numerals to objects or events according to rule". This
nonrealist, operationist definition of measurement allows psychologists to claim to be
measuring any variable of interest, regardless of whether or not it actually has a quantitative
structure; psychologists can make something quantitative simply by throwing numerals at it.
The two-stage breakdown in scientific practice is then reinforced by the social and economic
benefits of psychology's marketing itself as an applied science, and is propagated within the
various psychometrics and research methods curricula in the teaching institutions. Thus, "the
way in which psychometrics is currently typically taught actually subverts the scientific
method" (Michell, 2001, p. 211).
The extent to which psychology's "methodological thought disorder" remains
unconsciously entrenched within the mainstream is illustrated in Osbourne's (2010) recent
paper "Challenges for quantitative psychology and measurement in the 21st century". This is
the opening article in a new popular journal called Frontiers in Psychology (the kind of
journal mainstream psychologists might read). The author lays down the gauntlet, claiming
that one of the greatest challenges for quantitative psychology lies in "demonstrating in a
convincing way that quantification of behavioral, cognitive, biological, and psychological
processes is valid" (p. 1). He calls for scientific psychologists to "redouble their efforts to
convince the community of consumers of science that our numbers really represent what we
assume or propose that they represent", for "At stake is nothing less than the integrity and
future of our field" (p. 1). He warns that "To blindly accept the dogma of the field without
scholarly examination is to diminish what we do" (p. 1); instead, "We must be vigilant, as
researchers ... to continue questioning and examining our tacit assumptions" (p. 1). For
instance:
At this, the dawn of the 21st century, there are remarkably promising signs. Researchers
are beginning to understand that strict null hypothesis statistical testing (NHST) is
limiting and provides an incomplete picture of results. More journals now require effect
sizes, confidence intervals, and other practices one might argue are well overdue. (p. 2,
emphasis added)