The modernist conception of the autonomous ‘subject’ as centred, sovereign, and coherently rational, acting intentionally, knowledgeably, and volitionally, has been challenged from a variety of sources, including poststructuralism, feminism, and posthumanism. A different kind of attack on the modernist subject has recently been staged by neurobiologists who have started to decentre the subject from within—to ‘naturalise’ (and materialise) the subject. This biological naturalism—the new ‘life sciences’—claims to challenge our conceptions of self, the ethical subject, and what we conceive of as ‘life’. But what conceptions we have of the configurations of the self is fundamental to our understandings and conceptions of ethics. This paper traces a debate between German neurobiologists and (post)humanist philosophers on the ontology of such things as ‘free will’, ‘ethical agency’, and the ‘self' as an example of how the dispute between naturalists and nonnaturalist or postnaturalists is instrumental in sharpening our understanding of the self and of ethical agency. The paper argues that naturalism is bound to fail due to its inability to grasp the intersubjectivist nature of ethical agency, a theme which links up with recent geographical writing on ethics. I suggest, building on a recent contribution of Huib Ernste in this journal, that we should consider Helmuth Plessner’s concept of eccentric positionality and ontology of the possible as a postmetaphysical kind of ethical humanism.