Abstract
Although the subject of numerous contributions in the history of economics, the use of theoretical diagrams by economists is still quite misunderstood, as this practice is often characterized as a basic form of mathematization, soon replaced by more rigorous techniques of demonstration or exhibition. The present article attempts to challenge this view, focusing on a period of time, the 1930s, during which “diagrammatic economics” and other techniques coexisted, and on a specific community, that of students and young researchers from the London School of Economics with a keen interest in using diagrams as tools for economic reasoning. The cosmopolitan nature of research and education at the LSE, with its insistence on reading a vast amount of literature and attending seminars by a revolving cast of local and foreign lecturers, offered a favorable environment for a form of visual analysis that helped clarify concepts and resolve definitional issues, at a time when interest in various economic traditions had not yet given way to attempts to systematize and unify economic knowledge and its standards of production.
