This is wrong. Chalmers does not claim that a process could have exactly the same [computed] thoughts with or without it being conscious. What he claims is more like this: 1/ there's a gap in our understanding in that we can't explain why physical processes alone give rise to phenomenal consciousness; 2/ to prove that this "explanatory gap" exists, he says let's consider the scenario you describe ("p-zombies") as a thought experiment; 3/ since you cannot give any definitive reason why p-zombies are impossible, that proves that the gap in our understanding must be real. This argument does *not* require that p-zombies are actually possible in real life. It only requires us to be unable to explain why they're impossible. Indeed, Chalmers himself said "zombies are probably not naturally possible: they probably cannot exist in our world, with its laws of nature." At some point in the future, someone might eventually figure out a convincing explanation for why phenomenal consciousness occurs (e.g. that it happens inevitably as an "emergent property" of being functionally conscious). If so, that would be perfectly consistent with Chalmers' argument. He doesn't claim that there will *always* be a gap in our understanding. He's only saying that there is *currently* a gap in our understanding. Without a convincing explanation for phenomenal consciousness, ideas like it being "an emergent property of being functionally conscious" are essentially just hunches (albeit appealing ones). They don't explain how or why it occurs as an emergent property; they merely conjecture that it does. Chalmers is effectively calling them out as hunches, and saying that's why the hard problem is hard.
