Most students learn first that OU is used with indicative and MH is used
with everything else. However, the use of the negatives (OU always an
adverb whereas MH can serve as a conjunction or interrogative particle) is
far more complicated than that. MH can easily be used with indicatives in
certain circumstances, eg. Jn 3:18 hOTI MH PEPISTEUKEN EIS TO ONOMA
"because he has not believed in the name." MH used here because the nature
of the whold "he who believes . . . he who does not believe" does not call
for direct negations but hypothetical.
Also the negatives do not always negate the verb. In the case of 2 Cor
3:12 the comparative clause as a whole is negated not the understood verb
WMEN. What is being negated is an objective fact, thus OU is appropriate.
I wish I had references to cite, but my best resources are at the office
and I am working off the top of my head. I do recall reading about the
negatives in the old unabridged Grim/Wilke/Thayer, in the library at N.O.
Seminary.
Carlton Winbery
LA College