 A more fundamental criticism leveled against psychometrics is that it dogmatically presupposes that psychological attributes can be quantified. Michell (2000, 2004b) argues that psychometricians have not made serious attempts to test whether the attributes they purport to measure have quantitative structure, and instead adopted an overly loose conception of measurement that disguises this neglect. In response, Borsboom and Mellenbergh (2004) argue that Item Response Theory provides probabilistic tests of the quantifiability of attributes. Psychometricians who construct a statistical model initially hypothesize that an attribute is quantitative, and then subject the model to empirical tests. When successful, such tests provide indirect confirmation of the initial hypothesis, e.g. by showing that the attribute has an additive conjoint structure (see also Vessonen 2020).