Key commentators on person-centred care have described it as a "new ethic of care" which they link inextricably to notions of individual autonomy, action, change and improvement. Two key points are addressed in this article. The first is that few discussions about ethics and person-centred are underscored by any particular ethical theory. The second point is that despite the espoused benefits of person-centred care, delivery within the acute care setting remains largely aspirational. Choices nurses make about their practice tend to comply more often with prevailing norms than those championed by person-centred care. We draw on elements of work by moral philosopher Løgstrup and Foucault to provide insight into nurses' ethical conduct and ask why nurses would want to act otherwise, when what they think and do is viewed as normal, or think and act otherwise if doing so is seen within the organization as transgressive? To address these more specific questions, we discuss them in relation to the following constructs: the ethical demand, sovereign expressions of life and parrhêsia. We conclude by arguing that a ethical theoretical framework enables nurses to increase their perceptibility and appreciation of the ethical demand particularly those emanating from incommensurability between organizational norms and the norms invoked by person-centred care. We argue that nurses' responses to the ethical demand by way of parrhêsia can be an important feature of intra-organizational reflexivity and its transformation towards the delivery care that is more person-centred, particularly for older people with cognitive impairment. We conclude the article by highlighting the implications of this for nursing education and research.