 Economists in the 1930s (Hicks and Allen 1934) radicalised Pareto’s idea and argued that cardinal utility should be excluded in order to expunge economics from psychological hedonism. However, their concept of preference retained psychological content: people are assumed to act purposefully and therefore to have preferences that really constitute mental evaluations, rather than being ex-post rationalisations of behaviour (Lewin 1996). Furthermore, Ramsey (1926) and later von Neumann and Morgenstern (1944) devised formal tools allowing the representation of preference magnitudes as utility functions on an interval scale. This new utility, however, was very different from the older hedonic concept: the preference concept was basic. The cardinal utility function was constructed to reflect the preference ordering, but was not completely determined by it. 