Recent years have witnessed growing concerns about how we should conduct conservation activities in a world of human-altered biophysical conditions. The ‘novel ecosystems’ perspective has emerged as a way to meet this challenge. Yet its focus on accepting ‘new natures’ as the ‘new normal’ has drawn much criticism from those wedded to conventional forms of conservation, such as ‘ecological restoration’. This paper: 1) provides a much needed review of this dispute; 2) formulates and deploys an original analytical framework, which draws (...) on Thomas Kuhn's ‘theoretical history’ of science and Charles Taylor's moral philosophy to extricate the entangled moral and material ontologies of nature which conflate facts with values in the world-building activities of disputants; and 3) identifies and examines the processes underlying these world-building activities. The paper closes by offering an initial suggestion on how to explore options for resolving this highly contentious debate. (shrink)