This essay asks how we might best elaborate an ethics of authentic practice. Will we be able to agree on a set of shared terms through which ethical practice will be understood? How will we define ethics and the subject's relation to authoritative structures of power and knowledge? We begin by further clarifying our critique of evidence-based medicine (EBM), reflecting on the intimate relation between theory and practice. We challenge the charge that our position amounts to no more than ‘subjectivism’ and ‘antiauthoritarian’ theory. We argue that an ethical practice ought to question the authority of EBM without falling into the trap of dogmatic antiauthoritarianism. In this, we take up the work of Hannah Arendt, who offers terms to help understand our difficult political relation to authority in an authentic ethical practice. We continue with a discussion of Michel Foucault's use of ‘free speech’ or parrhesia, which he adopts from Ancient Greek philosophy. Foucault demonstrates that authentic ethical practice demands that we ‘speak truth to power.’ We conclude with a consideration of recent biotechnologies, and suggest that these biomedical practices force us to re-evaluate our theoretical understanding of the ethical subject. We believe that we are at a crucial juncture: we must develop an ethics of authentic practice that will be commensurable with new and emergent biomedical subjectivities.