Technologies of the future:: what can we know?: Alternative technological pathways in the 21st Century

Anticipative technological policy making needs technology foresight. The methods used include trend extrapolation, Delphi surveys, and technology demand analysis. It is shown that these methods are implicitly based on certain models of technological development, that they imply specific methodological problems and have their respective forecasting horizons. Specific emphasis is put on the question, how technology demands - arising from environmental or social problems - can be taken into account. The paper concludes with an exercise in vision assessment resulting in three speculative scenarios for alternative technological pathways in the 21(st) Century: a solar path, a cybiontic path, and a techno-spheric path.