Taking into account the relevant and mostly contemporary ango-american debates concering collective intentionality, the author examines what it means to share reasons and other intentional states such as thoughts and emotions.The guiding question of the dissertation is in what way and to what extent morality and therefore self-consciousness can be understood as conditions of possibility for the sharing of mental states, especially reasons. The dissertation is a contribution mainly to fields of research in practical philosophy (normative ethics and moral psychology) and in social philosophy (collective intentionality analysis) and rational choice theory.