Basically, Watsonian logic is in universe, and doylist is out of universe.

I first heard of those terms on gabrielleabelle's LJ and they're very helpful; as I said to spuffy_luvr though, if I need an out because I'm pissed at something or someone in the story and can't make sense of it, I always get to blame the writers. RL doesn't offer that "out" (damn it.)

I've noticed that Maggie's episode notes analyze the show entirely from a Watsonian perspective, and there actually is very little that occurs in the show that can't be accounted for in that way, which is fairly amazing.