I think the position that we shouldn't (or don't yet) have a unified uncertainty model is wrong

Did somebody solve the problem of logical uncertainty while I wasn't looking?

but I don't think it's so stupid as to be worth getting heated about and being uncivil.

I disagree that Gwern is being uncivil. I don't think Chapman has any ground to criticize LW-style epistemology when he's made it abundantly clear he has no idea what it is supposed to be. (Indeed, that's his principal criticism: the people he's talked to about it tell him different things.)

It'd be like if Berkeley asked a bunch of Weierstrass' first students about their "supposed" fix for infinitesimals. Because the students hadn't completely grasped it yet, they gave Berkeley a rope, a rubber hose, and a burlap sack instead of giving him the elephant. Then Berkeley goes and writes a sequel to the Analyst disparaging this "new Calculus" for being incoherent.

In that world, I think Berkeley's the one being uncivil.