Here at PEA Soup, Jason Kawall recently raised the possibility that moral realism might be open to a Euthyphro Dilemma kind of objection, which got me thinking about one of those papers that I write and then shelve for some reason or another. In this paper, I take a critical look at Russ Shafer-Landau’s moral realism (as presented in his aptly titled Moral Realism). I figured that perhaps this would be a good venue to discuss its argument.
Shafer-Landau thinks of his view as a kind of non-naturalism, but not of the substance dualism sort, according to which there is some sort of non-natural moral stuff in the world. Rather, he’s a (materialist) substance monist. But he’s also a property dualist: in addition to physical properties, there are irreducibly moral properties as well. This theory is ontologically akin to non-reductive materialism in the philosophy of mind, but Shafer-Landau considers his view epistemologically non-naturalist, since there is no science of ethics.
The worry I have about this view is fairly convoluted, but the basic point is as follows. Shafer-Landau (understandably) wants his view to avoid any “metaphysical profligacy,” a goal that he thinks is accomplished by (1) avoiding any non-physical substances and (2) making moral properties materialistically respectable by having them supervene on physical properties. I have no problem with (1), but I think (2) is suspect, because I think that all non-reductive materialist views fail to confer materialistic respectability upon non-material properties merely by virtue of the supervenience relationship.
The argument for rejecting (2) is a modified version of the argument that Michael Lynch and I put forth in our “The Impossibility of Superdupervenience.” (In addition to considering Shafer-Landau’s specific arguments, the more recent paper has beefed up the conclusion in various ways). Again, the nuts and bolts are as follows. (P1) If the supervenience relation is to transfer materialistic respectability from physical properties to moral properties, then that relation itself needs to be explained, and explained in a materialistically respectable way. (Others, such as Blackburn, Kim, and perhaps most thoroughly Horgan, are responsible for originally levying this explanatory burden; the basic intuition behind it is that even substance dualists have the moral supervene on the physical, so non-reductive materialists need to provide an explanation that presents a more robust supervenience in order to distinguish their views from dualism and make them materialistically respectable.) (P2) Non-reductive materialism does not, in principle, allow for a materialistically respectable supervenience relationship. (C) Thus, non-reductive materialists cannot use supervenience to transfer materialistic respectability from physical properties to moral properties.
Why is (P2) the case? Call the facts about the supervenience relation, whatever the theory in question may say about them, “S-facts.” In short, either the S-facts are themselves some facts of the physical world, which doesn’t do any work in connecting ontologically distinct physical facts to moral facts; or, the S-facts are sui generis, which is not materialistically respectable; or, finally, the S-facts themselves supervene on physical facts, which just generates an infinitely regressing, undischargable, and not materialistically respectable kind of “explanation” of how the moral supervenes on the physical.
As best I can tell, Shafer-Landau offers two rejoinders to the explanatory burden (focusing on Blackburn’s formulation of it). First, he rejects the burden (to, as he puts it, explain fundamental laws of morality) as a question-begging move by his opponents. But I fail to see why this might be question-begging. Each of the different possible ontological positions about moral properties has its own explanatory burdens; just like type-type reduction views must account for multiple realizability, one of the unique burdens of non-reductive views is to account for how ontologically distinct moral and physical properties could be correlated so tightly given the putative fact that they really are ontologically distinct. It would be question-begging to simply stipulate that this burden cannot be discharged; but since there’s an argument that it cannot be discharged (the trilemma in the last paragraph), that claim shouldn’t be question-begging either.
Second, Shafer-Landau does offer something of an explanation for how the moral supervenes on the physical: moral properties just are constituted by (and only by) physical properties. The main problem with this move that Lynch and I stress is that, in order to be a truly non-reductive view, the moral and the physical must be in some sense ontologically distinct. But for Shafer-Landau there is no ontological difference between the two – a fact about the moral world just is a fact about the physical world. So if he’s going to go the constitution-relation route, he can satisfy the burden of explaining the correlations between the moral and the physical, but only at the cost of reducing the moral to the physical (though not, of course, in a type-type way – and Shafer-Landau himself allows that there are other kinds of reductionism).