Scholars of 20th century history of economics have shown that during the years that immediately preceded and followed World War II, the monopoly of the repertoire of genuinely scientific economics changed in both holders and content. Indeed, we know now that the years between 1930 and 1960 constitute a critical juncture in which what thenceforth became mainstream economics emerged. The different trajectories, trainings and interests of postwar economists as well as the specific conditions that define the institutionalization of mainstream economics at specific institutional locations are now increasingly acknowledged and widely recognized. Nevertheless, heterogeneity, a constitutive characteristic and decisive element of explanation of the success of mainstream economics, remains a classificatory rather than an explanatory principle.

This paper aims to locate mainstream economics in a more encompassing frame by presenting it as a heterogeneous but coherent system, whose different pieces established different boundaries, and thus, served different functions in the process of monopolization of the repertoire of authentic scientific economics. The coherence of the system relies here in the mutual reinforcement of different processes of boundary-work. Boundary-work is referred here in the sense of Thomas Gieryn (Gieryn, 1983, 1995, 1999), that is to say, as a practical problem for scientists when confronting: 1) the demarcation of science from other intellectual activities (such as art, religion and folklore); 2) rival claims of (genuine) scientific approaches; and 3) the separation between the production of scientific knowledge and its consumption by non-scientists (the government and industry). Mainstream economics is thus studied neither as a single thing (much importance is given to the fact that the boundaries were drawn and redrawn over the time), nor as a monolithic force (the emphasis is put in the ambiguity of the different boundaries).

Specifically, the paper will focus on how, in the context of the Economics Department of the Massachusetts Institute of Technology (MIT), a demarcation was accomplished between 1930 and1960[1]. At the heart of the post-war processes of transformation of science, the Economics Department of the MIT was one of the key places where mainstream economics assured the monopoly of scientific economics. The main purpose of this paper is twofold. First, we will use MIT's idiosyncrasy to explain why the scholars gathering around this research center worked on specific boundaries of what soon became mainstream economics. Second, the analysis of MIT's boundary-work will be used to advance our understanding of its specific idiosyncrasy and therefore of the distances, tensions and agreements with the rest of mainstream economics.