Externalities, expectations, and growth

Summary. The paper studies a model of accumulation and growth where a continuum of heterogeneous firms play dynamically optimal strategies along a (rational expectations) equilibrium. The key feature of the model is that firms' technological decisions are assumed subject to both friction and external effects. This gives rise to a wide multiplicity of equilibrium behavior, any path of sustained growth requiring that the economy tackle a never-ending chain of fresh coordination problems. This setup is modelled as a (non-atomic) dynamic game, suitable conditions being provided that partially characterize when sustained growth is a possible (never the unique) equilibrium outcome. Received: May 25, 1995; revised version: March 25, 1998