This article discusses the roles of ethicists in the governance of synthetic biology. I am particularly concerned with the idea of self-regulation of bioscience and its relationship to public discourse about ethical issues in bioscience. I will look at the role of philosophical ethicists at different levels and loci, from the “embedded ethicist” in the laboratory or research project, to ethicists’ impact on policy and public discourse. In a democratic society, the development of governance frameworks for emerging technologies, such as synthetic biology, needs to be guided by a well-informed public discourse. In the case of synthetic biology, the public discourse has to go further than merely considering technical issues of biosafety and biosecurity, or risk management, to consider more philosophical issues concerning the meaning and value of “life” between the natural and the synthetic. I argue that ethicists have moral expertise to bring to the public arena, which consists not only in guiding the debate but also in evaluating arguments and moral positions and making normative judgments. When ethicists make normative claims or moral judgments, they must be transparent about their theoretical positions and basic moral standpoints.