Geometry of Money in the Neapolitan Eighteenth Century: Trojano Spinelli’s Riflessioni Politiche

In the 1750s, in the Italian states, the theme of monetary stability came to the center of public interest. In the Kingdom of Naples, particularly, the independence achieved under Charles of Bourbon stimulated many reform programs for the development and protection of foreign trade through direct political support. A prerequisite for this mercantilist perspective was monetary stabilization, since a weak and instable currency was the main obstacle to commercial integration. In the Neapolitan political debate on monetary reform, Trojano Spinelli’s essay Riflessioni politiche sopra alcuni punti della scienza della moneta has a greater significance, beyond its political influence, from a methodological point of view, being one of the first applications of the mathematical method to the study of economic problems. More specifically, Spinelli’s aim was to build a geometrically demonstrated science of money, using geometrical methodology. The main purpose of this paper is to delineate the intellectual context from which Spinelli’s essay emerged in order to show how a neutral approach proceeding by definitions, postulates, remarks, propositions, theorems, and corollaries, becomes a rhetorical expedient designed to support policy proposals.