[Elsie]He [Lincoln] left out the fact that just maybe, one of them is TRUE!
No he didn't.
Re-read Mr. Lincoln's words. His logic is correct; your reading comprehension is questionable.
Cordial suggestion: rapid-fire from-the-hip postings may not be an optimal strategy.
Less is often more.
Fearing that such pedantry may be required by some 'logically-challenged' posters, I'll offer this supplementary parsing of the logic here:
1. IF A, then NOT B, OR
2. IF B, then NOT A, OR
3. NEITHER A NOR B.
Mr. Lincoln was a brilliant man, of undiminihsed international stature. I hope he remains a hero within his own American Republican Party.
What part of MAY slips past YOUR comprehension?