John Locke is known within anthropology primarily for his empiricism, his views of natural laws, and his discussion of the state of nature and the social contract. Marilyn Strathern and Marshall Sahlins, however, have offered distinctive, novel, and broad reflections on the nature of anthropological knowledge that appeal explicitly to a lesser-known aspect of Locke’s work: his metaphysical views of relations. This paper examines their distinctive conclusions – Sahlins’ about cultural relativism, Strathern’s about relatives and kinship – both of which concern the objectivity of anthropological knowledge. Although Locke’s own views of relations have been neglected by historians of philosophy in the past, recent and ongoing philosophical discussions of Locke on relations create a productive trading zone between philosophy and anthropology on the objectivity of anthropological knowledge that goes beyond engagement with the particular claims made by Sahlins and Strathern.