Criminal law reform is often taken by theorists to be an abstract, even if normative, exercise in the analysis of doctrinal concepts. Such a picture of criminal law reform does not fit well with the task of the legislator who has to carry out such reform in a political context. How then should the legislator’s task in criminal law reform be understood? Can legal philosophy contribute to understanding that task? These questions are especially important in a political context of value pluralism and multiculturalism. This article urges that legal philosophy is relevant to criminal law reform seen from a legislative perspective. If a discourse of public reason is to be available in which legislators can conduct criminal law reform, philosophical reflection is needed to frame such a discourse and provide a principled foundation for public reason. The article aims to take some first steps in the direction of such principles.