Blackburn argues against naturalistic moral realism. He argues that there is no conceptual entailment from satisfying a naturalistic predicate to satisfying a moral predicate. But the moral is conceptually supervenient on the natural. However, this conjunction of conceptual supervenience with lack of conceptual entailment is something the non-realist can explain, but the realist cannot. I argue first that Blackburn’s best formulation of his challenge is his first one. Subsequently he reformulates it as a demand for a ‘ban on mixed worlds’. (...) Critics have directed their arguments against this formulation but they are ineffective against Blackburn’s first formulation. My second thesis is, even so formulated the realist can meet the challenge. The bare conceptual supervenience of the moral on the natural can be given a realist explanation by understanding names of moral properties as descriptive names of natural properties. (shrink)

Simon Blackburn’s supervenience argument—focusing on the mysterious “ban on mixed worlds”—is still subject to a variety of conflicting interpretations. In this paper, I hope to provide a defense of the argument that clarifies both the argument and the objections it must overcome. Many of the extant objections, I will argue, fail to engage the argument in its true form. And to counter the more compelling objections, it will be necessary to bring in additional argumentation that Blackburn himself does not clearly (...) provide. One important upshot of this discussion is that moral realism is not the only target of the argument: it raises trouble for a variety of metaethical views wed to realist-friendly construals of moral evaluation. Rightly understood, this argument not only survives the prominent responses, but turns out to be more powerful than his critics and Blackburn himself have recognized. (shrink)

In the 1970s and 1980s, Simon Blackburn published a number of much-discussed works in which he argued that the supervenience of the moral on the natural generates a serious problem for moral realism, a problem which his own brand of moral projectivism can avoid. As we will see below, Blackburn construed moral supervenience in terms of what is known as weak supervenience. Partly in response to Blackburn, a number of philosophers have argued that weak supervenience is too weak to capture (...) the intuitive sense in which the moral supervenes on the natural. Instead, it is argued, we should opt for strong supervenience, and, further, that strong supervenience completely disables Blackburn's argument against moral realism. This idea – that strong supervenience undermines Blackburn's argument – is very common in recent metaethics, and the purpose of the present paper is to develop a challenge to this near-orthodoxy. (shrink)