Among the third generation of human rights, the appeal for a diachronic solidarity between the human community and the extra-human natural world, and for a synchronstic one between the community of living human beings and hypothetical members of future human generations, has a significant place. This paper analyzes from a critical perspective the reasons for and against this proposal of duties and inter-generational ethical obligations in the context of a techno-scientific civilization, with the aim of grounding the current generation's responsibility regarding the elaboration of a global ethics that could face the demands of future generations. [ABSTRACT FROM AUTHOR]