The difference between genius and stupidity is that genius has its limits.
All too often, a plot thread depends on one or more characters doing something really stupid. They don't have any chance of doing the smart thing, because then the plot-driving conflicts wouldn't happen.
Even if the stupidity is an organic outgrowth of prior characterization, that doesn't necessarily make it contrivance-free. As addressed in The Movie
in the "Homer's Enemy" episode of The Simpsons
, the continued tolerance of Homer by his friends, his family, and his employer — indeed, his very survival
— is simply unbelievable at this point. Then again, Rule of Funny
Contrived stupidity commonly causes things like the collapse of A Simple Plan
in a Sitcom
or the effectiveness of Schmuck Bait
in Slasher Movies
. It is often accompanied by the meta-stupidity of the other characters' ignorance of Hanlon's Razor
. It is vulnerable to Fridge Logic
; however, do remember that Tropes Are Not Bad
On the other hand, it should be noted that many Contrived Stupidity Tropes are also Truth in Television
to some extent and have several Real Life
Contrast with Intelligence Tropes