Earlier quoted context omitted.
I think this is a case of trees and forest. Scifi doesn't require "a universe with internally self-consistent scientific laws." Or, if you want to hold on to that interpretation, there is no scifi. Not even the ones that uphold our current knowledge of physics, since that is known to be incomplete. Scifi --to me, but to many others as well-- is a thought experiment in prose. Like any work of fiction, it needs to have…
> Scifi --to me, but to many others as well-- is a thought experiment in prose. Like any work of fiction, it needs to have some consistency, but certainly not total. We can "suspend our disbelief." Then what, for you, is the distinction between Sci-fi and Fantasy? I think if you draw that line where most people draw it and think through what Chiang is actually doing, he's on the other side of it.
In sci-fi, there's often an (hypothetical) future setting/environment/world involved, but that doesn't really define the difference. The important part in sci-fi is how the events evolve in and how the characters react to and interact with that world, and how that particular definition of that world determines the outcome. The fantasy part is the main ingredient. It's a thought-experiment.
Chiang sets up a world, and his interest is in how that world affects "us" (the characters). It's not about the "arch" of the characters, but it's about the effect the world has on them.