I've been meaning to reply to this thread, regarding Botkin's plausibility. Thanks to Jim Twiggs for sending the amusing anecdotes about life at Cornell in the fifties. While these professors seem idiosyncratic, to be sure, their enthusiasms are basically disciplinary and don't, to my mind, come close to the kind of insanity we see in Kinbote. VN's EO commentary would have fit right in with these pursuits. I myself spend a lot of time shut up in my office composing wild theories about some Nabokov novel. Does that make me insane? (Don't answer.)
I went back and looked through the archives to see if I could find an answer to a question I once posed: what does Botkin teach at Wordsmith? The best answer seems to be that he teaches Scandinavian languages (since Nattochdag is a Swedish name, etc.) but this doesn't solve the problem. In the note to line 691, Kinbote has Sylvia O'Donnell say, "I wish I could figure out why anybody should be so keen on teaching Zemblan." It is clear, then, that Kinbote believes he taught Zemblan--and he has given us enough of the language to show that he could have done so. But of course it is impossible for him to have taught Zemblan, unless we accept that Zembla is a real place in the novel. (Even if Zembla were real, would a backwoods college like Wordsmith teach it?) Some may argue that since Kinbote has concocted this scene well after end of the semester, he has simply replaced his memory of teaching Scandinavian languages with a false memory of teaching Zemblan. But once we accept this as a solution, Kinbote's New Wye narrative becomes a house of cards--we have no way of knowing what really happened and what has been replaced ex post facto--or all is allowed, and we can pick and choose to suit our interpretive needs.
Another Botkin problem: if Kinbote is an alternative personality of V. Botkin, why is he so clearly a mirror opposite (and sometimes analog) of John Shade? The Shade/Kinbote dichotomy includes the following oppostitions and analogs, though I may be missing some things:
live across the lane from one another
all of the echoes that go back and forth between poem and commentary (see PFMAD, chapter 8).
born on the same day, wives resemble each other, came to New Wye at same time as John Shade's attack, both seem to be experts on Pope, etc...
It would make sense were Kinbote the opposite or analog of Botkin, but all of these relationships that should connect Kinbote to Botkin instead connect him to John Shade. Why? I do not doubt the thetic solution--that Kinbote=Botkin--but I don't think we can be satisfied with it, either.