Is "whether was not " equal to "whether"? [closed]
Solution 1:
The sentences I wondered whether his genius was governed by his mood and I wondered whether his genius wasn't governed by his mood say essentially the same thing. They are not opposites.
However the second uses the negative in order to emphasise what a remarkable proposition it would be, that someone's genius be governed by their mood. So remarkable that you wonder that it would be considered normal for it not to be the case.
Hence you might wonder if the intruder was not nine feet tall