Well, it's bold to assume anything about reality, because we only ever experience individual aspects of it. We can only try to model what we can observe. But a

Well, it's bold to assume anything about reality, because we only ever experience individual aspects of it. We can only try to model what we can observe. But as a counter to the assertion that "AC must be wrong because we can't really experience Banach-Tarski in the real world", it's perfectly valid to comment that "well, we also can't really observe continuous functions R -> R either". Or have you ever seen a least upper bound in real life?