Liberal theory seeks to achieve toleration, civil peace, and mutual respect in pluralistic societies by making public policy without reference to arguments arising from within formative ideals about what gives value to human life. Does it make sense to set aside such conceptions of the good when it comes to controversies about stem cell research and the genetic engineering of people or animals? Whether it is reasonable to bracket our world-views in such cases depends on how we answer the moral questions that the use of these biotechnologies presuppose. I argue that the moral language of liberal justice - of rights and duties, interests and opportunities, freedom and consent, equality and fairness - cannot speak to these underlying concerns about what the human embryo is, why the natural lottery matters to us, and whether 'animal nature' is worth preserving. I conclude that liberal theory is incapable of furnishing a coherent or desirable account to govern the way we use our emerging powers of biotechnology.