This paper discusses the relevance of a complex natural ethics for the health field, especially for public health, avoiding the main dichotomies inherited from the tradition of modernity, such as subject/object; public/private; value in se/value per se. This thesis considers the contributions of the epistemology of complexity highlighting the conceptual constellation of links and changes between the first (bio-ecological) nature' and 'second (socio-cultural) nature' of human beings. It poses a dialogue between the two main principles that guide discussions of bioethics: the Life Sanctity Principle and the Life Disposability Principle. Natural ethics assumes both principles as necessary to a contemporary ethics divided between the adoption of an unavoidable polytheism of values and norms, resulting from the secularization of the late-modem world- marked by tolerance and pluralism - and the search for the necessary foundations for this 'open society', which cannot be reduced either to the epistemological skepticism of anything goes or to the corrosive moral skepticism of the law of 'survival of the fittest', ending up in a lifeboat ethics.
'natural' ethics; complexity; Life Sanctity Principle; Life Disposability Principle