This dissertation provides a critical analysis of public administration's understanding of the relationship between rational thought and action in its discourse on ethics. It argues that rationalist ethics assume a particular relationship between thought and action: that good knowledge leads to good, proper action. While there have been many critiques of rationalist administrative ethics, scholars have not examined the way in which rationalism persists in the way in which the teaching of ethics is conducted. The use of the case study figures prominently in this. Thus, the dissertation explores the historical and theoretical intersection of rationalism, ethics, and teaching through the lens of the case study. It begins with a history of the pedagogical use of the case study and the institutional transformations of the university. While conventional accounts of the field locate its founding in the United States in the municipal reform movement, here the founding of the field of public administration is recast through connections to reforms in the university including changes in epistemic assumptions, pedagogical methods, and curricular changes in ethics in which the case study is central and remains so as the field develops. The dissertation then considers scholarship in public administration that raises questions about rationalist ethics. Three critical approaches are explored: recognition of the uncertainty and complexity of administrative practice, critique as unmasking of power relationships, and the shift of ethics from an epistemological to an ontological inquiry. The dissertation builds on the work in this third approach and shows how it attempts to articulate a non-rationalist, or immanent, ethics. This ethics is concerned with exploring the conditions that make possible mutually beneficial relationships and meaningful lives from which categorical norms of the good life could emerge. Drawing on the philosophy of Gilles Deleuze and Felix Guattari, it is argued that the distinction Deleuze and Guattari make between "arborescent" and "rhizomatic" knowledge gets to the root of the tension between thought and action and offers an innovative and useful way to advance an immanent, non-rational ethics. The challenge digital technologies and the information society present to the field is considered to illustrate the need to rethink administrative ethics and also the particular usefulness of Deleuze and Guattari in doing so. The dissertation concludes with a discussion of pedagogical practices and classroom examples that encourage a rhizomatic understanding of the theory and practice of public administration.