In case of the bat sonar, the answer is even simpler, IMO: we lack the capacity to experience what the world sonars like to a bat, except in the vaguest terms. Again, I don't see this is a problem
I see that as a problem for the claim that mind-brain identity theory explains qualia. It does not enable us to undestand the bat's qualia, or to predict what they would be like. However, other explanations do lead to understanding and predicting.
Again, I'm not entirely sure I understand what additional things we need to explain w.r.t qualia.
Understanding and predicting.
I guess I'm not entirely sure what you mean by "understanding" and "predicting". As I said, if we could scan the bat's brain and figure out how all of its subsystems influence each other, we would know with a very high degree of certainty what happens to it when the bat receives a sonar signal. We could identify the changes in the bat's model of the world that would result from the sonar signal, and we could predict them ahead of time.
Thus, for example, we could say, "if the bat is in mid-flight, and hungry, and detects its sonar ...
[Cross-posted.]
1. Defining the problem: The inverted spectrum
A. Attempted solutions to the inverted spectrum.
B. The “substitution bias” of solving the “easy problem of consciousness” instead of the “hard problem.”
2. The false intuition of direct awareness
A. Our sense that the existence of raw experience is self-evident doesn’t show that it is true.
B. Experience can’t reveal the error in the intuition that raw experience exists.
C. We can’t capture the ineffable core of raw experience with language because there’s really nothing there.
D. We believe raw experience exists without detecting it.
3. The conceptual economy of qualia nihilism pays off in philosophical progress
4. Relying on the brute force of an intuition is rationally specious.
Against these considerations, the only argument for retaining raw experience in our ontology is the sheer strength of everyone’s belief in its existence. How much weight should we attach to a strong belief whose validity we can't check? None. Beliefs ordinarily earn a presumption of truth from the absence of empirical challenge, but when empirical challenge is impossible in principle, the belief deserves no confidence.