Linkages, thresholds, and development

Growth is rare historically, with short expansions interspersed with long p eriods of stasis. We examine how well this can be explained by a general cl ass of Schumpeterian growth models that treat development as a progress thr ough a space of commodities, from simple to more complex foods. This proces s of sequential innovation in a partially ordered network of commodities is called linkage formation. The central result of this article is that Schum peterian 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.