There were two things I should have said in yesterday’s post that I didn’t say. So this is in part a retraction (since what I’ll say now qualifies what I said then), in part an addition, and in part an apology for doing an incomplete job the first time.
First, I was presupposing throughout the post that there is such a thing as *a* difference between the natural and gruesome predicates. That might not be right. There might be several distinctions to be drawn in the area, and the vague talk we make of natural and gruesome predicates cuts across the real distinctions. I haven’t seen their paper, but I believe Maya Eddon and Chris Meacham have been developing a line like this in some work, and it might be right. I refuse to believe there is *no* distinction between natural and gruesome predicates, but there might be several relevant distinctions in the area, and if so we have to say things more carefully than I did.
Second, I left out one very important option in my survey of how we might define naturalness for special science terms. In recent work Barry Loewer has been arguing that a Humean can define naturalness via the theory of laws. (I want to be a bit careful here, because Loewer’s paper isn’t published, or even available on “his website”:http://philosophy.rutgers.edu/FACSTAFF/BIOS/loewer.html, but I think what I’ll say here is public record from his various presentations of the material.) Lewis thought that we needed to define naturalness before we could work out what the laws are, but Loewer argues (a) that Lewis’s arguments to this effect don’t work, and (b) that we can work out what the laws are and what the natural properties are simultaneously. I think (a) is right and (b) is an interesting step towards a solution. That’s to say, there is an interesting step towards a solution in existence, so some of the pessimism of yesterday’s post was unwarranted. Whether there would be any epistemological payoff from Loewer’s metaphysical theory (even if it were true) is a further, and difficult, question.