This article makes a contribution to the on-going debates about universalism and cultural relativism from the perspective of sociology. We argue that bioethics has a universal range because it relates to three shared human characteristics,--human vulnerability, institutional precariousness and scarcity of resources. These three components of our argument provide support for a related notion of 'weak foundationalism' that emphasizes the universality and interrelatedness of human experience, rather than their cultural differences. After presenting a theoretical position on vulnerability and human rights, we draw on recent criticism of this approach in order to paint a more nuanced picture. We conclude that the dichotomy between universalism and cultural relativism has some conceptual merit, but it also has obvious limitations when we consider the political economy of health and its impact on social inequality.