This article is based on a discourse analysis of the complete nursing records of 45 patients, and concerns the modes of rationality that mediated text-based accounts relating to patient care that nurses recorded. The analysis draws on the work of the critical theorist, Jurgen Habermas, who conceptualised rationality in the context of modernity according to two types: purposive rationality based on an instrumental logic, and value rationality based on ethical considerations and moral reasoning. Our analysis revealed that purposive rationality dominated the content of nursing documentation, as evidenced by a particularly bio-centric and modernist construction of the workings of the body within the texts. There was little reference in the documentation to central themes of contemporary nursing discourses, such as notions of partnership, autonomy, and self-determination, which are associated with value rationality. Drawing on Habermas, we argue that this nursing documentation depicted the colonisation of the sociocultural lifeworld by the bio-technocratic system. Where nurses recorded disagreements that patients had with medical regimes, the central struggle inherent in the project of modernity became transparent--the tension between the rational and instrumental control of people through scientific regulation and the autonomy of the subject. The article concludes by problematising communicative action within the context of nursing practice.