John Tasioulas1, Effy Vayena2. 1. Yeoh Tiong Lay Centre for Politics, Philosophy and Law, The Dickson Poon School of Law, King's College London, London, UK; Radcliffe Institute for Advanced Study, Harvard University, Cambridge, MA, USA. Electronic address: john.tasioulas@kcl.ac.uk. 2. Institute of Biomedical Ethics and History of Medicine, University of Zurich, Zurich, Switzerland.