Natural economic quantities and their measurement

This paper discusses and develops an important distinction drawn by Jevons, viz. that between natural and fictitious quantities. This distinction provides a basis for a theory of economic concept formation that aims at picking out families of models that are phenomenally adequate, explanatory and exact simultaneously. Essentially, the theory demands of an economic quantity to be natural that (1) it is explained by a causal model, (2) it is measurable and (3) the measurement procedure is justified. The proposed theory is tested against two case studies, one historical and one contemporary.