Linkages, thresholds, and development

Growth is rare historically, with short expansions interspersed with long periods of stasis. We examine how well this can be explained by a general class of Schumpeterian growth models that treat development as a progress through a space of commodities, from simple to more complex foods. This process of sequential innovation in a partially ordered network of commodities is called linkage formation. The central result of this article is that Schumpeterian growth models exhibit generic threshold behavior. Below a critical probability of linkage formation, development gradually ceases. Above the critical probability, innovation continues with probability one.