I don't know how accurate to Japanese this really is, but I like to think of でしょう/だろう as a suggestive (I don't know the official terms, I think you called that 'volitional') copula. In the part where でしょう was first introduced, when I hear that, I usually think of it as the person suggesting whatever quality is accurate for the situation. In the second case, it is still suggestive, but a little sarcastic-sounding, hence the implication that the person speaking truly believes whatever the sentence is describing is fact, and even feels a little annoyed that the listener didn't notice.
Oddly enough I picked that idea up from my Japanese teacher muttering to herself about how slow some of my fellow students can be...she says amusing things sometimes.
Don't know if that was helpful or even correct, I just found it interesting to think about.
I don't know how accurate to
I don't know how accurate to Japanese this really is, but I like to think of でしょう/だろう as a suggestive (I don't know the official terms, I think you called that 'volitional') copula. In the part where でしょう was first introduced, when I hear that, I usually think of it as the person suggesting whatever quality is accurate for the situation. In the second case, it is still suggestive, but a little sarcastic-sounding, hence the implication that the person speaking truly believes whatever the sentence is describing is fact, and even feels a little annoyed that the listener didn't notice.
Oddly enough I picked that idea up from my Japanese teacher muttering to herself about how slow some of my fellow students can be...she says amusing things sometimes.
Don't know if that was helpful or even correct, I just found it interesting to think about.