Commentary on a hard problem thought experiment
Abstract
In the seventh paragraph of the post, you say "This question [which machine, if any or both, is conscious/] seems to be in principle unfalsifiable, and yet genuinely meaningful." (I'm assuming that you mean that any answer to it is unfalsifiable.) My neo-Carnapian intuitions diagnoses the problem right at this point. Forget about attributions of meaningless and all that stuff. Replace it in your statement with more pragmatically-oriented evaluative notions: theoretically fruitless, arbitray without even being helpful for any theoretical, experimental, or practical purpose, and so on. Any answer to the question will be those. Thus the question is not worth pursuing, especially since the thought experiment is science fiction right now. A much more useful way to spend one's time is addressing frutiful questions, like the ones involved in constructing your postulated robots, or investigating neural mechanisms, and so on. So acknowledge the connection between unfalsifiability/verifiability/confirmability and theoretical and practical worthlessness (rather than "meaningless"). Then get on with the theoretically and empirically worthwhile questions. Many of the latter are quiter abstract and "philosophical," anyway (about the scope and limits of various methodologies, existing theories, and so on). Aren't those enough to occupy even the most abstract theorist's attention? Why puzzle about questions whose answers can't be rationally justified?