Abstract
In contrast to work showing exogenous social influences on the production of economic ideas, this article asks how a market's own infrastructure can endogenously shape practitioners' economic perspectives. It investigates this question by comparing the evolution of opposed views on speculation across two 19th-century American futures markets. The analysis locates the origins of this divergence in features of the grading, receipting and contracting processes that linked these new derivative markets to underlying agricultural markets. This connective infrastructure both made possible new speculative practices and established market ontologies from which traders theorized the economic significance of those practices. These ontologies served as distinct cores around which incompatible constellations of ideas - including beliefs about price relations between spot and futures markets, the character of the global market and the motives and capabilities of speculators - were elaborated.