1 Published in Australasian Journal of Philosophy 87 (2009) MORAL REALISM AND PROGRAM EXPLANATION: A SHORT SYMPOSIUM REPLY TO NELSON Alexander Miller In chapter 8 of Miller 2003, I argued against the idea that Jackson and Pettit’s notion of program explanation might help Sturgeon’s non-reductive naturalist version of moral realism respond to the explanatory challenge posed by Harman. In a recent paper in the AJP [Nelson 2006], Mark Nelson has attempted to defend the idea that program explanation might prove useful to Sturgeon in replying to Harman. In this note, I suggest that Nelson’s argument fails. 1. Nelson’s Objection In chapter 8 of Miller 2003, I argued against the idea that program explanation, as developed by Frank Jackson and Philip Pettit [1990], might help Nicholas Sturgeon’s non-reductive naturalist version of moral realism [1988] respond to the challenge posed by Gilbert Harman [1977]. I argued: M1. Higher-level properties are causally relevant in a way that can earn them ontological rights only if they figure in the best explanation of experience, considered from the point of view of a subject who suffers no epistemic limitations vis a vis lower-level properties and the process explanations in which they appear.