The ‘public interest’ has long been used as a concept to justify planning activity. However, attempts to specify how to determine the public interest have been so plagued with problems that the concept has been effectively abandoned by academia in recent years. This article stresses the ongoing relevance of the public interest concept in planning but does so in a way that reconceives what it entails. This article argues that central to the concept of the public interest is how ‘the subject’ is conceived. It is contended that the currently prevalent collaborative and agonistic approaches to planning present a deficient understanding of the subject as one detached from the intersubjectively formed moral frameworks that provide understanding of context and supply bearing for action. This article seeks to address this deficit by introducing the philosophy of Alasdair MacIntyre to a planning audience. MacIntyre’s communitarian perspective offers an alternative view of the subject by stressing how an evaluation of what constitutes the public interest is unavoidably undertaken from within a shared tradition of moral reasoning. Thus, from a MacIntyrean position, the public interest should not be assumed to simply constitute the end product of correct procedures. This article highlights the importance of acknowledging how identifying the public interest demands situated ethical judgement. The concluding section of this article details the dangers for planning theory and practice of failing to acknowledge this phenomenon.