The need for a global ethics has its origin in the human situation as such (i.e. in the fact of hominisation that has dismissed us from the natural security of animal instincts and thrown us into the state of freedom) and especially in the present situation of humankind that is characterised by an extreme increase of external challenges to our co-responsability, brought about by the results of natural science, technology, politics and economy, and - as it appears - lacking internal resources of ethical reason. The present book tries to show that the transcentendal-pragmatic approach to discourse ethics can reconstruct the genesis of this situation and provide a rational response to the external challenges to and the internal deficits of global ethics.