Measurement as a normative practice - Implications of Wittgenstein's philosophy for measurement in psychology

Recently, a number of prominent measurement specialists (e.g. Cliff, 1992; Schonemann, 1994) have pondered the lack of progress in the development of convincing solutions to the measurement problems of psychology, and have attempted to identify the factors responsible for this lack of progress. They suggest a number of possibilities, including a basic lack of talent in the ranks of the social sciences. It is argued here, however, that the philosophy of Wittgenstein provides an interesting alternative explanation. Specifically, despite their apparent differences, current approaches to the support of psychological measurement claims are unanimous in viewing measurement as chiefly an empirical matter. On Wittgenstein's account, however, this is a mischaracterization of measurement, for, as he argued in elaborate detail, measurement is a normative, rule-guided practice. Hence, empirically based argument is not relevant to the support of measurement claims. If this verdict is correct, it explains not only the failure of measurement theory in psychology, but the much discussed success of measurement in the physical sciences. In this paper, Wittgenstein's characterization of measurement, and its implications for psychology, are discussed.