It would seem that you believe that. So what is your proof?

Proof is only meaningful in a system of shared assumptions (physics) or axioms (logic).

I'm glad you recognize that. Then you should also recognize that for reasons having nothing to do with logical necessity you have accepted some things as true which are unprovable, in your case a particular interpretation of how to do Bayesian.

All you have offered so far is assertion, and the appearance that you don't even realize that you are making assumptions until after it is pointed out. When I found my self in that position, it humbled me a bit. In Bayesian terms, it moved all of my estimates further from 0 and 1 than they had been.

In any case, whatever program you have used to decide what you could assume, what if your assumptions are incomplete? What if you simply haven't tried hard enough to have something "more than zero" on the moral side?

If moral realists, or anyone else, doesn't agree to Bayesianism or another commonly understood framework of proof, logic, and common assumptions, then I'm not interested in talking to them (about moral realism).

So you have picked your church and your doctrine and you wish to preserve your orthodoxy by avoiding intelligent apostates. This is not a new position to take, but it has always seemed to me to be a very human bias, so I am surprised to see it stated so baldly on a website devoted to avoiding human biases in the twenty-first century. Which is to say, are you SURE you want to treat your assumptions as if they were the one true religion?

However, the situation for moral realism isn't "unproven conjecture", it's more like "unformalized conjecture whose proponents refuse to specify what it actually means". At least that's the state of debate in this thread.

Why limit yourself to this one thread, populated as it isn't by anyone who claims any real expertise?

Yet you assign sufficient probability to moral realism to think it's worth discussing or reading about. Otherwise you'd have said from the start, "I agree with you that moral realism has no evidence for it, let's just drop the subject". To have such a high prior requires evidence. If you don't have such evidence, you are wrong.

Your particular rejection of moral realism doesn't seem to reflect much knowledge. For a Bayesian, knowing that other intelligent minds have looked at something, gathered LOTS of evidence and done lots of analysis, and reached a different conclusion than your prior should LOWER your certainty in your prior. Finding one guy who can't or won't spoonfeed you concentrated moral realism, and claiming on that basis that your prior of essentially zero must stand is not at all how I interpret the Bayesian program. In my interpretation, it is when I am ignorant that my mind is most open, that my estimates are furthest from 0 and 1.

I wish someone like Eliezer, or who knows his morality well enough, would pipe in on this, because from my reading of Eliezer, he is also a moral realist. Not that that proves anything, but it is relevant bayesian evidence.