Mathematical Psychics and Hydraulics: The Methodological Influence of Edgeworth and Fisher

The scientific methodology of classical physics has been a constant influence in the development of orthodox economics. Clear signs of this can be found in the works of many classical economists such as Smith, Say, Cairnes and Mill. The physics influence became more apparent with the emergence of marginalism. The economic thought of F. Y. Edgeworth, however, is the peak of the influence of classical physics to economics. In Edgeworth’s Mathematical Psychics, the identification of maximum energy in physics with that of the maximum pleasure in economic calculus, is central in his thought. In the same manner, I. Fisher, the founder of marginalism in the US, promoted a classical physics based economic methodology. The close analogy of physics and economics concepts and the application of tools from hydrodynamics to economic theory, are basic characteristics of his work. These views eventually dominated orthodox economic methodology. The paper argues that, apart from establishing the physics scientific ideal in economics, both of these authors provided the methodological justification for its adoption in economics. It also examines their subsequent influence on the formation of the current methodological approach in orthodox economics. In particular, it discusses their influence on key components of current mainstream economics such as: extensive use of mathematics, aversion to methodological discourse and anti-psychologism.