Political theory and philosophy need to widen their view of the space in which what matters politically takes place, and I suggest that integrating the conditions of sustainability of all affected—that is, all participants in nature's relations—is a necessary first step in this direction. New materialists and posthumanists have challenged how nature and politics have traditionally been construed. While acknowledging the significance of their contributions, I critically examine the ethical and political implications of their ontological project. I focus particularly on (...) how the decentering of human agency that they advocate for raises a set of concerns that need to be addressed in developing an appropriate ecological ethics. I argue that the latter must be attuned to the vulnerability of living beings who participate in relationships that sustain life on earth. This brings me to conclude that qualitative distinctions between the worlds ofbiosandtechneare necessary. This is because we need to think critically about ways of evaluating types of relationships so that we can assess them and establish which are worth nurturing and protecting and which are not. (shrink)