The 2-D Argument Against Metaethical Naturalism

A few years back I noted that 2-D semantics provides a straightforward refutation of synthetic metaethical naturalism (SEN):  SEN implies that moral terms differ in their primary and secondary intensions, this is clearly false (moral terms are "semantically neutral", or exhibit 2-D symmetry, in that their application to a world does not vary depending on whether we consider it as actual or as counterfactual), and so SEN must be false.

As I've been developing this argument in my paper 'Moral Symmetry and Two Dimensional Semantics', it occurs to me that 2-D semantics enables an even broader argument against metaethical naturalism.

Carroll on Zombies

Zombies are back in the news!  Via the DN Heap of Links, I see physicist Sean Carroll defending what appears to be a kind of analytical functionalism:

What do we mean when we say “I am experiencing the redness of red?” We mean something like this: There is a part of the universe I choose to call “me,” a collection of atoms interacting and evolving in certain ways. I attribute to “myself” a number of properties, some straightforwardly physical, and others inward and mental. There are certain processes that can transpire within the neurons and synapses of my brain, such that when they occur I say, “I am experiencing redness.” This is a useful thing to say, since it correlates in predictable ways with other features of the universe. For example, a person who knows I am having that experience might reliably infer the existence of red‐wavelength photons entering my eyes, and perhaps some object emitting or reflecting them. They could also ask me further questions such as “What shade of red are you seeing?” and expect a certain spectrum of sensible answers.
There may also be correlations with other inner mental states, such as “seeing red always makes me feel melancholy.” Because of the coherence and reliability of these correlations, I judge the concept of “seeing red” to be one that plays a useful role in my way of talking about the universe as described on human scales. Therefore the “experience of redness” is a real thing.

This is manifestly not what many of us mean by our qualia-talk.  Just speaking for myself: I am not trying to describe my behavioural dispositions or internal states that "correlate [...] with other features of the universe" in "useful" ways.  I have other concepts to do that work, concepts that feature in the behavioural sciences (e.g. psychology).  Those concepts transparently apply just as well to my imagined zombie twin as to myself.  We could ask the zombie 'further questions such as "What shade of red are you seeing?" and expect a certain spectrum of sensible answers.'  But this behaviouristic concept is not such a philosophically interesting one as our first-personal concept of what it is like to see red -- a phenomenal concept that is not properly applied to my zombie twin.

So I worry that Carroll is simply changing the subject.  Sure, behavioural dispositions and internal cognitive states (of the sort that are transparently shared by zombies) are "real things".  Who would ever deny it?  But redefining our mentalistic vocabulary to talk about these (Dennettian patterns in) physical phenomena is no more philosophically productive than "proving" theism by redefining 'God' to mean love.

How bad?

Compare five seriously bad things:

(1) Unjust discrimination along the lines of racism, sexism, etc., in Western countries.
(2) War and terrorism
(3) Global poverty
(4) Animal suffering (from factory farming)
(5) Global catastrophic (i.e. civilization-ending) risks

Just how bad is each of these, in the world as we find it today?  If you could prevent just one of them, which would it be?  (What would your rank ordering be if you weren't sure how many philanthropic wishes the genie was going to give you?)