The recent proposal by Douglas and Savulescu for an ethics of knowledge provokes a renewed consideration of an enduring issue. Yet, the concept raises significant challenges for procedural and substantive justice. Indeed, the operationalisation of ‘an ethics of knowledge’ could be as alarming as what it seeks to prevent. While we can acknowledge that there is, and surely always will be, potential for misuse of beneficial science and technology, a contemplated conception of what we ought to not know, devise or (...) disseminate sets before us an enormously complex task. This essay challenges an ethics of knowledge to respond to concerns of procedural and substantive justice. While the concept has a certain appeal, it does not appear to adequately address certain fundamental issues as it is currently presented. Here, the author invites consideration of two primary points: (1) who should decide, based on whose interests? and (2) could such an exercise actually be effective in achieving its goal? (shrink)