SUMMARY
This paper analyses the fundamental problems of defining and achieving sustainable development. A common core of the various definitions of sustainability circulating is identified. Economic and scientific approaches to operationalize sustainability generally lead to management rules, which — if obeyed — should guarantee sustainability. Since it is not possible to precisely predict the future, this scientific—technical—economic route to sustainability may fail. A second, ethical way, to sustainability which interprets sustainability as an ideal for fair play is introduced. How the two different ways may complement one another with a three-step hierarchy of political goals is elucidated.