Volution of T Echnologies : a N a Ssessment of the S Tate - of - the - a Rt

Scholars from a wide variety of disciplines who have studied technological advance in some detail have converged on the proposition that technological advance needs to be understood as proceeding through an evolutionary process characterized by multiple search efforts, deep intertechnological differences in the ways potential opportunities are tagged, ubiquitous uncertainty and innovation-driven competition among firms. In this work we survey the state-of-the-art in the analysis of such evolutionary processes. We start by asking whether there are some invariances in the knowledge structure and in the ways technological knowledge accumulates and, together, what distinguishes different fields and different periods of technological advance, if any. Next we address (i) the differences across paradigms in terms of nature and sources of innovative opportunities; (ii) the mechanisms of appropriation of economic returns from innovative activities; (iii) the role of demand and other socio-economic factors in shaping the directions of technological advances; (iv) the possibility of identifying discrete families sectors, distinct according to their sources of innovative knowledge and modes of innovating; (v) the relationships between the nature of productive knowledge and the distribution of input coefficients across firms; (vi) the patterns of innovation diffusion; and, finally, (vii) we discuss the role of history in the evolution of technologies, that is their path-dependence.