The author concludes the volume by reflecting on the interface between philosophy and law, arguing that they are both complementary and interdependent. He shows examples of the legal translation of philosophical principles and stresses the necessity to establish a system of responsibility – that is, a clear system of sanctions – so that philosophical and legal norms do not remain mere gratuitous statements. The chapter reflects on the philosophical foundations of legal responsibility, the historical movement of gradual individualization of responsibility and the shift to joint obligation to respond to collective threats and challenges. It ultimately argues that classical responsibility reduced to an essentially inter-individual relationship is technically very sophisticated, both philosophically and legally, but insufficient to face collective challenges (in particular the environmental crisis).