Unlocking the Mystery of the Origins of John von Neumann’s Growth Model

In his famous "A Model of General Economic Equilibrium", von Neumann wrote that it was "obvious to what kind of theoretical models [his] assumptions correspond." To date, however, his sources of economic insights about the functioning of the continuously growing price-economy that he modeled have remained a total mystery. Based on archival material, this mystery is solved in this account by making visible the specific influences from economics and mathematics that inspired him. I argue that von Neumann's 1937 paper resulted from a deep engagement with economics as it was emerging at the beginning of the 1930s and that this happened as he was travelling and crossing national boundaries while bridging distinct branches of mathematics with different local perspectives in economics. His encounters with Jacob Marschak in Berlin, Nicolas Kaldor in Budapest, and Frank Graham in Princeton as well as his reading of Walras's, Wicksell's and Cassel's work would be key. I also explain how he came to realize that there existed a formal analogy between systems of linear equations and inequalities with which he characterized (stationary and dynamic) economies and the minimax theorem for two-person zero-sum games that he had conceived and proved in 1928.