Are you saying that I must subscribe to the physical realism because of moral considerations?
No. But your position (or any position) on physical realism has implications in meta-ethics. Personally, those implications are the only reason I find the physical realism debate interesting at all.
In other words, a moral realist who is a physical anti-realist is very confused. In general, the desire of all realists is to have a consistent definition of "real" for both physical entities and moral facts. (Probably, we all desire it, but realists believe the characteristic "real" is a worthwhile label to try to apply).
I'm confused by your stance because you seem to think one's position on physical realism has no bearing on one's moral position. Whereas I think most of the motivation for (interesting) arguments about physical realism are outgrowths of disputes in other kinds of realism debates.
I'm confused by your stance because you seem to think one's position on physical realism has no bearing on one's moral position.
Not quite. I assert that instrumentalism/physical pragmatism gives you a cleaner path to moral considerations than physical realism. The resulting positions may or may not be the same, depending on other factors (not all physical realists have the same set of morals, either). But not getting sidetracked into what exist and what doesn't and instead concentrating on accurate and inaccurate models of past, present and future inputs lets you bypass a lot of rubbish along the way. Unfortunately, it does not let you avoid being strawmanned by everyone else.
The Litany of Tarski (formulated by Eliezer, not Tarski) reads
If the box contains a diamond,
I desire to believe that the box contains a diamond;
If the box does not contain a diamond,
I desire to believe that the box does not contain a diamond;
Let me not become attached to beliefs I may not want.
This works for a physical realist, but I have been feeling uncomfortable with it for some time now. So I have decided to reformulate it in a more instrumental way, replacing existential statements with testable predictions. I had to find a new name for it, so I call it the Litany of Instrumentarski:
If believing that there is a diamond in the box lets me find the diamond in the box,
I desire to believe that there is a diamond in the box;
If believing that there is a diamond in the box leaves me with an empty box,
I desire to believe that there is no diamond in the box;
Let me not become attached to inaccurate beliefs.
Posting it here in a hope that someone else also finds it more palatable and unassuming than straight-up realism.
EDIT: It seems to me that this modification also guides you to straight-up one-box on Newcomb, where the original one is mired in the EDT vs CDT issues.
EDIT2: Looks like the above version resulting in people confusing desiring accurate beliefs with desiring diamonds. It's about accurate accounting, not about utility of a certain form of crystallized carbon.
Maybe the first line should be modified to something like "If I later find a diamond in the box...", or something. How about the following?
If I will find a diamond in the box,
I desire to believe that I will find a diamond in the box;
If I will find no diamond in the box,
I desire to believe that I will find no diamond in the box;
Let me not become attached to inaccurate beliefs.
For some reason the editor does not let me use the <strike> tag to cross out the previous version, not sure how to work around it.