Earlier quoted context omitted.
I was right there with you until you mentioned Searle. :-) The Chinese room argument is bad in that it hides an assumption of mind/body dualism. If you believe that humans have "souls" and other things do not, then you have a qualitative difference between a human or a machine. On the other hand, if you are a materialist then you are faced with the problem that humans don't have much understanding of semantics either…
Searle's one of the most die-hard materialist philosophers of mind around. It's his materialism that leads him to make his argument. Computers and human brains are both made out of atoms but that doesn't mean they're not qualitatively different. By that logic I"d be no different from a tree. There's qualitative differences between computers and human brains. Our cognition is biochemical and horribly slow , just by vi…
Searle seems to see a distinction between the "substrates" (which means an LLM cannot be intelligent; it's running on regular computer hardware and there's nothing to be found which "understands"), but unless someone can point out exactly what part of the substrate is intelligent, I am going to continue to suggest that his substrate difference is exactly identical to having a soul or not having a soul.
I, as a materialist, assert that, if you dug through my noggin down to the level of subatomic particles you will never find anything that is intelligent or which understands. (Quantum mechanics does not help here, by the way. It just replaces a (rather naive) determinism with randomness---see Bell's Inequality.) There is no magic going on there. You and your tree are both doing nothing but chemistry and physics (you share something like 50% of your genes, by the way). And that means that a computer could, in principle, behave as intelligently as I do. That's "substrate independence".
Now, whether a given system does do so or not is another question entirely. :-)