It is argued that philosophical realism is well suited to serve as a perspective from which to understand nursing, and that it should be considered as an alternative to positivist, interpretivist, hermeneutical and phenomenological approaches. However, existing forms of realism, including theory and entity realism are shown to be faced with serious problems. In response, an alternative form ‘constraint realism’ is outlined, and shown to be apposite for illuminating the rule or convention governed behaviour characteristic of human beings. A brief (...) sketch is offered of its application to the social practice of nursing. (shrink)