"You mean my whole fallacy is wrong."

If you do an internet search for "Annie Hall script pdf", the files that come up have the line in.

I have no idea how accurate those scripts are compared to what they were shooting with.

What I do know (from interviews and biographies and things) is that
1. There was a LOT of ad-libbing
2. There was a LOT of culled material - a whole murder mystery subplot that got cut out later became Manhattan Murder Mystery.
3. The scripts I found also seemingly have accounted for every stutter and trailing-off - including during the scene in the bar with Annie and the music producer (Paul Simon) which, according to the interviews and things I've read, was basically unscripted, so...maybe the accuracy isn't that great.
4. There were a lot of different cuts and versions, a lot of re-shoots, too, and the film's plot was really found in the edit (apparently) where the focus was turned onto Alvy and Annie's relationship specifically. Apparently that wasn't the obvious main plot at the outset of filming.

All that is to say that the line might have been an adlib or not. It's almost impossible to say what was intended from the outset and what "just happened" with Annie Hall.