The paper demonstrates the compatibility between competition as a rivalry among firms and increasing returns resulting from innovative choice. The analysis offers the prospect of a general theory of economic evolution. It is carried out by means of a model, which makes it possible to exhibit the time structure of production processes and to sketch out the sequential interaction of decisions in a process of restructuring of productive capacities for the whole economy. It shows that several firms can coexist in the market, despite the existence of increasing returns, yet remain differentiated not so much because they supply differentiated goods, but because they are each one at a different stage of the life cycle of the production process.