"The course of technical change is neither controlled by a logic of evolution beyond the scope of social actors nor regulated by any social actor according to his intentions and interests. Macro approaches which assume that a single logic determines technical change exclude one another. They conceive social actors only as executors or as victims of technical progress. Micro approaches supposing a rational choice or social construction of technology often overrate the importance of a single collective actor, like the corporation or the military, and underrate the mechanisms of structural selection. The author proposes a social evolutionary approach to explain technical change. He illustrates its strength with empirical examples. Micro processes of local variation, that means actors' definitions and closings of technological projects, are coupled with macro processes of global selection between different paths of technological development. Within this frame, the leading question is answered in the end: If we assume that it is during the early phases of generation that a type of technology is endowed with its characteristic genetic make-up, then it is the research system's social embedment and the scientists' and engineers' cultural concept which influence the course of technical change more than other social forces..." Erschienen in: Soziale Welt 43. Jahrg., H. 1 (1992), pp. 7-25