The arguments levelled by J L Mackie against objective values and moral realism still have sway over many philosophers. In this paper I carefully analyze these arguments. My analysis covers the following areas: 1) his notion of objective value, 2) his metaethical methodology, 3) his attempt at outlining a normative ethics in light of his metaethical skepticism, and 4) his understanding of the concept "institution". I conclude that a version of moral realism can be maintained in the face of Mackie's (...) arguments. I offer a moral realist rejoinder to each of the four above areas and the rebuttals culminate into a thesis I call contextual moral realism. (shrink)