Decision makers addressing the ecological crisis face the challenge of considering complex ecosystems in their socioeconomic decisions. Complementary to ecological sciences, other scientific frameworks, grouped under the umbrella term environmental sciences, offer decision makers the opportunity to pursue sustainable paths. Because the environmental sciences are drawn from different branches of science, environmental ethics must go beyond the legacy of ecology and the life sciences to describe the contribution of scientific knowledge to addressing the ecological crisis. In this regard, I analyze (...) and compare three environmental sciences based on their seminal articles: Conservation Biology, Sustainability Science, and Sustainability Economics. My analysis shows that conservation biology and sustainability economics share strong similarities despite their different disciplinary backgrounds (life _versus_ social sciences). Both seek to contrast a biocentric and an anthropocentric perspective. The goal of sustainability is therefore understood as a balance that must be found between these two perspectives. If the issue of balancing human and non-human interests is still relevant to sustainable science, it is more likely to take place in an ecocentric perspective based on alternative ontological and normative prescriptions. Based on this analysis, I distinguish between ‘proscriptive value-based’ scientific work that cannot be used for policy advice but is flexible to different value systems, and ‘prescriptive value-based’ scientific work that can be used for policy advice but is fixed within a given value system. Conflicting recommendations from environmental scientists therefore result from the coexistence of multiple ‘prescriptive value-based’ scientific approaches based on different conceptions of the relationship between humans and nature. (shrink)