In this paper I wish first of all to argue against two possible views about colour qualities, which I shall label the Objectivist and Subjectivist views respectively. I find these views to be prevalent among philosophers of my acquaintance, though sometimes they are hidden by a veneer of post-Wittgensteinian sophistication. Part of my argument will depend on modern scientific theories of colour vision. In the second part of the paper I shall argue for a different view of my own.

Environmental ethics in its modem classical expression by Aldo Leopold appears to fall afoul of Hume’s prohibition against deriving ought-statements from is-statements since it is presented as a logical consequence of the science of ecology. Hume’s is/ought dichotomy is reviewed in its historical theoretical context. A general formulation bridging is and ought, in Hume’s terms, meeting his own criteria for sound practical argument, is found. It is then shown that Aldo Leopold’s land ethic is expressible as a special case of (...) this general formulation. Hence Leopold’s land ethic, despite its direct passage from descriptive scientific premises to prescriptive normative conclusions, is not in violation of any logical strictures which Hume would impose upon axiological reasoning. (shrink)